Progress 10/01/23 to 09/30/24
Outputs
PROGRESS REPORT Objectives (from AD-416): Irrigation and nutrient management are key factors that impact sustainable and profitable production of high-quality small fruit and nursery crops. The goal of this project is to develop new approaches that integrate water and nutrient management methods with other environmental and cultural constraints to improve the quantity and quality of berry, wine grape, and nursery crops grown in the Pacific Northwest (PNW) while protecting the environment. Objective 1: Determine requirements for high-quality berry crop production through monitoring and management of water, nutrients, and soil. [NP 305, Component 1, Problem Statement 1B] Subobjective 1A: Adapt and refine remote sensing technology to monitor water and nutrient deficits and determine irrigation and fertilizer needs in berry crops. Subobjective 1B: Assess the feasibility of using deficit or pulsed-drip irrigation to increase water use efficiency and protect regional water quality in berry crops. Subobjective 1C: Develop new fertigation and soil management practices to increase production and fruit quality in blueberry. Objective 2: Develop approaches to manage vineyard canopies, soils, and nutrients for improved grape production, plant health, and fruit quality. [NP 305, Component 1, Problem Statement 1B] Subobjective 2A: Develop an integrated nitrogen (N) management approach encompassing N use in both the vineyard and winery to identify the most effective and efficient manner to manage N inputs to improve wine quality and protect water quality. Subobjective 2B: Examine how canopy architecture, vine density, and crop load interact to identify the most efficient use of sunlight and soil water resources to improve production efficiency of Pinot noir. Subobjective 2C: Understand how N management practices influence beneficial arbuscular mycorrhizal fungi (AMF) in grapevines to develop more sustainable methods for farming grapes. Subobjective 2D: Determine the impact of rootstocks on root development and AMF colonization when challenged by the northern root knot nematode. Objective 3: Evaluate the impact of management practices for water and nutrients on tolerance to abiotic and biotic stress in specialty crops. [NP 305, Component 1, Problem Statement 1C] Subobjective 3A: Develop new management practices and disease control measures to minimize pathogen damage and losses for woody nursery plants. Subobjective 3B: Define salinity thresholds for specialty crops so growers can reduce losses of planting stock, mitigate salinity impacts on quality, and broaden the use of more salt tolerant species in systems considered marginal for production of other crops. Subobjective 3C: Develop and evaluate water and nutrient management practices for specialty crops grown in soilless substrates. Approach (from AD-416): Experiments will be conducted in the greenhouse and field on small fruit (blueberry, raspberry, strawberry, grapevines) and other specialty crops including nursery crops (Rhododendron, Vaccinium, Basil), and in growth chambers on root pathogens. For Obj. 1 we will develop remote sensing based crop coefficients and water stress indices for irrigation of blueberry and raspberry, and will test the following hypotheses: Deficit irrigation will reduce water use but have no effect on yield or fruit quality when it is applied at early stages of fruit development or after harvest in blueberry or raspberry; Pulsed-drip irrigation will reduce water use and increase yield and production relative to conventional irrigation in blueberry and raspberry; Application of P and B by fertigation will result in greater yield and fruit quality than granular or foliar fertilizers in blueberry; Biostimulants are most effective when applied at low rates and during peaks in root production. For Obj. 2 we will test these hypotheses: Maintaining low N status in the vineyard will enhance wine composition as compared to boosting N supply in the vineyard; Varying N supply to Pinot noir alters berry and wine phenolic composition to a greater extent than P or K; Altering the VSP trellis to increase canopy solar exposure at midday will increase productivity but not alter ripening or fruit quality in Pinot noir; Soil and foliar applied N in vineyards reduces AMF colonization and P uptake; Nitrogen inhibition of AMF colonization in grape roots increases with N dose; Nitrogen is a more potent inhibitor of AMF as vine P increases; Root development and AMF colonization differ among rootstock genotypes when northern root knot nematode is present. We will test the following hypotheses for Obj. 3: Critical temperatures for vegetative growth and zoospore formation of Phytophthora isolates will be similar within a species; fungicide sensitivity of Phytophthora is greatest at the optimal temperature for growth; Root rot induced by flooding is more severe than rot under moisture conditions common in nurseries; Reducing water availability minimizes root damage caused by Phytophthora in rhododendron; Increasing N increases root damage caused by Phytophthora in rhododendron; Crop tolerance to salinity will differ among production systems; Southern highbush blueberry plants have different substrate needs than northern highbush blueberry; Strategies to improve water distribution in substrates will increase growth and production in blueberry. Measurements and techniques used in these studies will include standard approaches to measure plant growth, biomass, and yield, plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), fruit quality (refractometry, titratation, HPLC, sensory perception), root production and mycorrhizal colonization (soil cores, microscopy), soil pH and EC, soil water content (TDR, tensiometers), plant and soil nutrients (CNS analyzer, ICP), and pathogen growth (microbiological media) and root damage (visual ratings). We will also utilize multi-spectral cameras and drones to develop new methods to measure plant water status. This report documents FY 2024 progress for project 2072-21000-055-000D, ⿿Water and Nutrient Management for Sustainable Production of Small Fruit and Nursery Crops, which began in April 2020. In support of Sub-objective 1.A, ARS researchers in Corvallis, Oregon, collected multispectral and thermal images from blueberry, blackberry, and raspberry fields using a small unoccupied aerial system (drone). The images were processed and analyzed for normalized difference vegetation index (NDVI) and canopy temperature. The NDVI images provided clear information on canopy development and the amount of irrigation required at each site. Thermal images were also useful, particularly for assessing spatial variability in water status of the fields and determining whether the plants are irrigated sufficiently. Additional trials were initiated with large weighing lysimeters (devices used to measure plant water use) to validate the relationships between canopy cover and irrigation water requirements in blueberry and blackberry. For Sub-objective 1.B.1, results were published on using deficit irrigation in blueberries, and with support from the industry, a new trial was initiated in blackberries rather than raspberries. The plants were managed with or without irrigation after harvest and measured for water status during postharvest water deficits, cold hardiness over the winter, and yield and fruit quality in the following summer. The data from the first two years of the study were analyzed. The final year of data on yield and fruit quality will be collected this summer. Under Sub-objective 1.B.2, field trials evaluating the benefits of pulse drip irrigation were completed in commercial blueberry and raspberry fields located in Washington state. Soil water content, yield, fruit quality, plant water status, leaf and soil nutrients, and canopy development were measured for two years at each site. Data were analyzed from both trials, and the results were published in two manuscripts. For Sub-objective 1.C.2, ARS researchers conducted a trial on the use of biostimulants in raspberries. Plants were treated with commercial biostimulants containing glycine betaine, silicone, or kelp extract and exposed to temperatures greater than 95 degrees F for 28 days. Measurements on the plants included photosynthesis, transpiration, and water use efficiency; leaf florescence and anthocyanins; and total dry weight of the roots and shoots. Analysis of the data indicated that glycine betaine and kelp extract increased growth and photosynthesis in the plants and enhanced their tolerance to heat stress. A manuscript was written and submitted for publication. Additional trials with both biostimulants were initiated this spring in experimental field plots of blueberry and blackberry. In support of Sub-objective 3.C.2, a two-year trial was completed to evaluate irrigation methods for growing potted blueberry plants in soilless substrate. The plants were harvested destructively and analyzed for growth, root development, and nutrients in the leaves and stems. Fruit was also harvested and analyzed for size, firmness, sugar content, and acidity. Analysis of the data indicated that growth and yield were greatest when irrigation was triggered frequently and applied using a new type of multi-outlet drip emitter that was designed to apply water evenly over the surface of the substrate and prevent dry spots in the pots. A manuscript is partially written and will be submitted for publication. Artificial Intelligence (AI)/Machine Learning (ML) Neither artificial intelligence (AI) or machine learning (ML) methods were used for this project during FY 2024. ACCOMPLISHMENTS 01 Pulse irrigation increases fruit production in blueberries and raspberries. Pulse irrigation is the practice of applying water in cycles of 20-60 minutes every day until the total amount required by a crop is added. If managed correctly, the practice can prevent water limitations, particularly on sandy or silty soils, which are commonly used for many berry crops. In conjunction with grower collaborators, ARS scientists in Corvallis, Oregon, tested the feasibility of using pulse irrigation in commercial blueberry and raspberry fields. Relative to the conventional practice of irrigating continuously for 12-13 hours every two days, pulse irrigation increased yield by as much as 3,000 pounds of fruit per acre within the first year of application, which based on market prices was equivalent to $8,560/acre. Pulsing also increased yield by an average of 1,100 pounds or $980/acre in raspberry. As a result of this research, growers in Oregon and Washington state are beginning to use pulse irrigation in their berry fields. 02 Water requirements for irrigating blackberries. Irrigation scheduling requires knowledge of several factors, including rooting depth and the daily water requirements of the crop. ARS researchers in Corvallis, Oregon, used large underground weighing devices called ⿿lysimeters to accurately measure daily water use in trailing blackberries, which are grown on roughly 6,200 acres in the United States. At full production, the plants required nearly a half-gallon of water from either rain or irrigation to produce just one blackberry and over 12.5 gallons of water to produce enough berries to fill a six-ounce clamshell. Additional measurements indicated that the plants extracted water primarily from the top two feet of soil on cooler days and up to four feet deep on warmer days. This information will enable blackberry growers to make informed decisions on how much water to apply and determine how frequently irrigation is needed to avoid water limitations to fruit production. 03 Best way to apply boron fertilizer to blueberries. Boron (B) is essential for flowering and fruit development but is often deficient in many crops, including blueberries. ARS researchers in Corvallis, Oregon, investigated different methods of applying B in a mature blueberry field irrigated by drip, including soil applications, foliar applications, and fertigation, which is the practice of applying liquid fertilizer through the irrigation water. Foliar application was the most effective method for increasing the concentration of B in the leaves, roots, and fruit, followed by fertigation with B fertilizer. Soil application of B, on the other hand, was ineffective and resulted in less sugar in the fruit than fertigation or foliar applications. Findings from this work provides valuable new information for improving nutrient management in blueberry. 04 A new process for recovering nutrients and clean irrigation water from municipal wastes. With increasing water shortages, irrigation with reclaimed water is becoming necessary for securing agricultural production in many regions. In collaboration with Oregon State University, an ARS researcher in Corvallis, Oregon, investigated the feasibility of using a novel hybrid electrodialysis-forward osmosis (ED- FO) process, designed for simultaneous recovery of nutrients and clean water from municipal wastewater, as a means for safe production of food crops. The final product water from the process was tested and evaluated for hydroponic production of lettuce and kale. The process recovered 84-96% of the nutrients from the effluent and reclaimed up to 74% of the clean water. Both ED and FO had low-fouling potential, and plants grown in nutrient water recovered from the process had a similar amount of growth as those grown with conventional fertilizers. According to an economic analysis, the hybrid ED-FO process is promising for scalable implementation and highly attractive in terms of resource recovery, waste footprint reduction, and water quality enhancement. 05 Nitrogen fertilizer requirements are lower than expected in mature blueberry fields. Most crops require nitrogen (N) fertilizer, but multiple studies over the past four decades have shown that insufficient or excessive use of N fertilizer can negatively affect both yield and fruit quality in blueberries. A portion of the N required for plant growth is often available from soil organic matter, but the amount released is difficult to predict and usually not considered in N fertility programs. In collaboration with Washington State University, an ARS researcher in Corvallis, Oregon, conducted a series of laboratory and field experiments to identify when and how much N is available from soil organic matter. The amount released ranged from 15 to 110 pounds of N per acre in soils collected from mature commercial blueberry fields. Availability peaked in June, which is when the plants take up most of their N during the growing season. Consequently, fertilizer rates as low as 30-45 pounds of N per acre were sufficient to sustain production for three years at sites with 3% to 28% soil organic matter. This combined with longer-term observations from other studies suggests that N fertilizer rates could be reduced to lower input costs with no consequences to fruit production. 06 Heatwave causes excessive nutrient losses from potted nursery plants. Controlled-release fertilizers (CRFs) are water-soluble pellets that slowly release essential nutrients into soil or soilless potting media. In collaboration with Oregon State University, an ARS researcher in Corvallis, Oregon, carried out an experiment with CRFs that were designed to supply nutrients for six to seven months in several important nursery crops, including roses and maple trees. During the experiment, the region experienced a series of heatwaves in June that caused unanticipated and excessive release of nutrients from the fertilizers. As a result, the nutrients were leached from the pots, and extra fertilizer had to be added. These results indicate that new climate-ready practices are needed to sustain nursery production under extreme heat.
Impacts
(N/A)
Publications
- Sloan, C., DeVetter, L.W., Griffin-Lahue, D., Benedict, C., Bryla, D.R., Lahue, G. 2024. Nitrogen supply from soil organic matter: Predictors and implications for recommended nitrogen application rates in northern highbush blueberry. HortScience. 59(6):725-735. https://doi.org/10.21273/ HORTSCI17632-23.
- Leon-Chang, D.P., Bryla, D.R. 2024. Applying boron by fertigation or as a foliar fertilizer is more effective than soil applications in northern highbush blueberry. HortScience. 59(5):565-570. https://doi.org/10.21273/ HORTSCI17461-23.
- Nackley, L., Mccauley, D., Scagel, C.F. 2023. Hot mess: Heatwave effects on controlled-release fertilizer. HortScience. 58(11):1459-1460. https:// doi.org/10.21273/HORTSCI17325-23.
- Caroll, J.L., Orr, S.T., Davis, A.J., Strik, B.C., Bryla, D.R. 2024. Water use by ⿿Columbia Star⿿ trailing blackberry in western Oregon. Irrigation Science. https://doi.org/10.1007/s00271-023-00912-4.
- Carroll, J.L., Orr, S.T., Benedict, C.A., DeVetter, L.W., Bryla, D.R. 2024. Feasibility of using pulse drip irrigation for increasing growth, yield, and water productivity of red raspberry. HortScience. 59(3):332-339. https://doi.org/10.21273/HORTSCI17467-23.
- Tran, Q., Garcia-Jaramillo, M., Schindler, J., Eness, A., Bryla, D.R., Patel, H., Navab-Daneshmand, T., Jin, X. 2024. Sustainable nutrient water recovery by a hybrid electrodialysis (ED) - forward osmosis (FO) process for agricultural application. Journal of Environmental Chemical Engineering. 12(2). Article 112091. https://doi.org/10.1016/j.jece.2024. 112091.
- Carroll, J.L., Orr, S.T., Retano, A., Gregory, A.D., Lukas, S.B., Bryla, D. R. 2024. Weather-based scheduling and pulse drip irrigation increase growth and production of northern highbush blueberry. HortScience. 59(5) :571-577. https://doi.org/10.21273/HORTSCI17527-23.
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Progress 10/01/22 to 09/30/23
Outputs
PROGRESS REPORT Objectives (from AD-416): Irrigation and nutrient management are key factors that impact sustainable and profitable production of high-quality small fruit and nursery crops. The goal of this project is to develop new approaches that integrate water and nutrient management methods with other environmental and cultural constraints to improve the quantity and quality of berry, wine grape, and nursery crops grown in the Pacific Northwest (PNW) while protecting the environment. Objective 1: Determine requirements for high-quality berry crop production through monitoring and management of water, nutrients, and soil. [NP 305, Component 1, Problem Statement 1B] Subobjective 1A: Adapt and refine remote sensing technology to monitor water and nutrient deficits and determine irrigation and fertilizer needs in berry crops. Subobjective 1B: Assess the feasibility of using deficit or pulsed-drip irrigation to increase water use efficiency and protect regional water quality in berry crops. Subobjective 1C: Develop new fertigation and soil management practices to increase production and fruit quality in blueberry. Objective 2: Develop approaches to manage vineyard canopies, soils, and nutrients for improved grape production, plant health, and fruit quality. [NP 305, Component 1, Problem Statement 1B] Subobjective 2A: Develop an integrated nitrogen (N) management approach encompassing N use in both the vineyard and winery to identify the most effective and efficient manner to manage N inputs to improve wine quality and protect water quality. Subobjective 2B: Examine how canopy architecture, vine density, and crop load interact to identify the most efficient use of sunlight and soil water resources to improve production efficiency of Pinot noir. Subobjective 2C: Understand how N management practices influence beneficial arbuscular mycorrhizal fungi (AMF) in grapevines to develop more sustainable methods for farming grapes. Subobjective 2D: Determine the impact of rootstocks on root development and AMF colonization when challenged by the northern root knot nematode. Objective 3: Evaluate the impact of management practices for water and nutrients on tolerance to abiotic and biotic stress in specialty crops. [NP 305, Component 1, Problem Statement 1C] Subobjective 3A: Develop new management practices and disease control measures to minimize pathogen damage and losses for woody nursery plants. Subobjective 3B: Define salinity thresholds for specialty crops so growers can reduce losses of planting stock, mitigate salinity impacts on quality, and broaden the use of more salt tolerant species in systems considered marginal for production of other crops. Subobjective 3C: Develop and evaluate water and nutrient management practices for specialty crops grown in soilless substrates. Approach (from AD-416): Experiments will be conducted in the greenhouse and field on small fruit (blueberry, raspberry, strawberry, grapevines) and other specialty crops including nursery crops (Rhododendron, Vaccinium, Basil), and in growth chambers on root pathogens. For Obj. 1 we will develop remote sensing based crop coefficients and water stress indices for irrigation of blueberry and raspberry, and will test the following hypotheses: Deficit irrigation will reduce water use but have no effect on yield or fruit quality when it is applied at early stages of fruit development or after harvest in blueberry or raspberry; Pulsed-drip irrigation will reduce water use and increase yield and production relative to conventional irrigation in blueberry and raspberry; Application of P and B by fertigation will result in greater yield and fruit quality than granular or foliar fertilizers in blueberry; Biostimulants are most effective when applied at low rates and during peaks in root production. For Obj. 2 we will test these hypotheses: Maintaining low N status in the vineyard will enhance wine composition as compared to boosting N supply in the vineyard; Varying N supply to Pinot noir alters berry and wine phenolic composition to a greater extent than P or K; Altering the VSP trellis to increase canopy solar exposure at midday will increase productivity but not alter ripening or fruit quality in Pinot noir; Soil and foliar applied N in vineyards reduces AMF colonization and P uptake; Nitrogen inhibition of AMF colonization in grape roots increases with N dose; Nitrogen is a more potent inhibitor of AMF as vine P increases; Root development and AMF colonization differ among rootstock genotypes when northern root knot nematode is present. We will test the following hypotheses for Obj. 3: Critical temperatures for vegetative growth and zoospore formation of Phytophthora isolates will be similar within a species; fungicide sensitivity of Phytophthora is greatest at the optimal temperature for growth; Root rot induced by flooding is more severe than rot under moisture conditions common in nurseries; Reducing water availability minimizes root damage caused by Phytophthora in rhododendron; Increasing N increases root damage caused by Phytophthora in rhododendron; Crop tolerance to salinity will differ among production systems; Southern highbush blueberry plants have different substrate needs than northern highbush blueberry; Strategies to improve water distribution in substrates will increase growth and production in blueberry. Measurements and techniques used in these studies will include standard approaches to measure plant growth, biomass, and yield, plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), fruit quality (refractometry, titratation, HPLC, sensory perception), root production and mycorrhizal colonization (soil cores, microscopy), soil pH and EC, soil water content (TDR, tensiometers), plant and soil nutrients (CNS analyzer, ICP), and pathogen growth (microbiological media) and root damage (visual ratings). We will also utilize multi-spectral cameras and drones to develop new methods to measure plant water status. In support of Sub-objective 1A, remote images were collected from commercial fields of blueberry and raspberry and analyzed for normalized difference vegetation index (NDVI) and canopy temperature. The NDVI images provided clear information on plant canopy development and irrigation requirements at each site, while the thermal images were used to assess spatial variability in water status of the fields. Additional images are being collected this year to develop a crop water stress index (CWSI) for blackberry. In support of Sub-objective 1.B.1, a new trial on deficit irrigation was initiated in blackberry. Irrigation was scheduled automatically using a large weighing lysimeter, and treatments included irrigation and no irrigation after harvest. Deficit irrigation reduced water use by 54 percent (%) but had no effect on primocane growth during the first year of treatment. We are currently measuring yield and fruit quality in the plants from each treatment. In support of Sub-objective 1.B.2, field trials evaluating the benefits of pulse drip irrigation were completed in blueberry and raspberry. Both studies were conducted in mature, commercial fields located in Washington state. Soil at the sites were loam and silt loam, respectively. Plants in the blueberry field were managed organically and harvested for the fresh market, while those in the raspberry field were managed conventionally and harvested for the processed market. Within the first year of application, pulsing increased yield in blueberry by 2200 kg·ha-1 when irrigation was applied at a fixed rate (grower based) and by 3290 kg·ha-1 when irrigation was scheduled based on daily estimates of crop evapotranspiration. Pulsing also increased yield by 1230 kg·ha-1 in year 2 and 1210 kg·ha-1 in year 3 when irrigation was applied at a fixed rate in raspberry. Based on current market prices, increases in production with pulsed drip were equivalent to $11,680⿿21,160/ha in blueberry and $2, 420⿿2,460/ha per year in raspberry. Higher production was due primarily to greater berry size in blueberry and to more and larger floricanes in raspberry. Overall, pulsed drip irrigation appears to be a promising method for improving production of blueberry and raspberry, but more research on the use of this practice on other soil types is needed. Manuscripts on the studies were prepared and submitted for publication. In support of Sub-objective 1.C, we repeated a trial on the response of highbush blueberry to humic substances. Plants were grown in a complete nutrient solution with four rates of humic acids, including 0, 100, 200, and 300 mg·L-1 of active ingredient (a.i.). The results confirmed our previous results and indicated that humic acids increased shoot dry weight by an average of 36% when plants were grown with 200-300 mg·L-1 a. i. A manuscript on the study was prepared for publication, and humic acids were tested in a new field trial on five commonly grown cultivars of blueberry, including ⿿Aurora⿿, ⿿Cargo⿿, ⿿Duke⿿, Draper, and ⿿Top Shelf⿿. In support of Sub-objective 2.A.1, all field experiments and winery addition experiments with varying nitrogen were completed, and the sensory analysis of all wines was also completed. The first manuscript from this trial focusing on Chardonnay was published. The second manuscript on Pinot noir is partially complete and has been sent to collaborators to complete their parts. For Sub-objective 2.A.2, we are still waiting to conduct the detailed high-performance liquid chromatography analysis as our collaborator has been unable to complete her laboratory renovation due to supply chain issues. The fruit remains frozen and will be analyzed this fall and winter. In support of Sub-objective 2.B, the second-year field data were collected for soil moisture profiles, plant growth and yield, and vine nutrient and water status. However, due to a frost event shortly after budbreak, there was so little fruit remaining on vines that we could not apply different crop levels to the vines. We continued to explore a solar panel device (similar to the ⿿Paso panel⿿) to measure sunlight interception and showed that this approach was effective in estimating solar interception by the canopy. We also collected gas exchange measures, vine nutrient and water status measures and yield. Fruit quality metrics including degree Brix, pH, titratable acidity, and mineral nutrient levels in the must were also examined, but we did not make wines this year since one of our three main factors (crop load) could not be applied. This trial is ongoing, and the different crop levels will be applied this year. In support of Sub-objective 2.C.1, all data were analyzed and a manuscript using this data was completed. We also began preparing another manuscript which we hope to complete over the next few months. Work that was planned for Sub-objective 2.C.2 was discontinued as explained previously, and we completed a new greenhouse study using chambers added to potted grapevines where either roots could gain access to nitrogen in the chambers or only mycorrhizal hyphae. Results were promising although the system does not work well with soluble forms of N that leached across chambers irrespective of the mesh size. A new experiment using this chamber system with only organic N sources is being planned. In addition, we grew grass plants for 8 months in the greenhouse that were supplied with heavy nitrogen (N15) and produced a large quantity of N15 labeled residue for future experiments. For Sub-objective 2.C.3, we completed a greenhouse study where we manipulated nitrogen and phosphorus supply using a factorial design and analyzed the plant growth and nutrient uptake data. This experiment showed no interaction between nitrogen and phosphorus levels on arbuscular mycorrhizal fungi (AMF) function, and that AMF do not help vines obtain nitrogen from soil, even though high nitrogen reduced AMF colonization. Our results were not expected, and we are designing a new study to assess if AMF can help vines obtain nitrogen from organic sources of N. We also began new work to examine if potassium (K) applications in vineyards will alter AMF root colonization and planned a greenhouse trial to examine how varying levels of soil K influence AMF and if AMF influence K uptake and how this interacts with other nutrients. In support of Sub-objective 2.D, all research and analysis were completed, and another paper was published. In support of Objective 3.A, research evaluating factors altering horticultural crop root health continued as planned. In addition, we completed collaborative research optimizing detection methods for the boxwood blight pathogen and how temperature influences disease. Continued collaborative research evaluating effects of irrigation and plant spacing on the spread of the boxwood blight pathogen was begun. Continued collaborative research establishing how pathogens associated with root rot in nursery plants differ in sensitivity to fungicides. Continued collaborative research improving methods for producing reliable inoculum of root rot pathogens. In support of Sub-objective 3.A.1, and 3.A.2, research was completed establishing critical temperatures for growth, reproduction, and fungicide sensitivity of pathogens associated with root rot in nursery crops. In support of Sub-objective 3.A.3, research was completed to identify how substrate moisture alters the incidence and severity of root rot in nursery crop and identified whether research techniques used in studying root rot are representative of what occurs under nursery conditions. In support of Sub-objective 3.A.4, we completed trials to assess whether irrigation practices that reduce water availability can alter disease, analyzed data, and currently writing manuscript. In support of Objective 3.B, a trial evaluating effects salinity on growth and quality of basil grown in different production systems was finished. We collected and analyzed pathological and physiological data and began writing a manuscript. We also continued collaborative research quantifying fertilizer run-off from nursery crops and use of remote imaging for management of nursery plant nutrition and irrigation and how heat waves alter fertilizer efficiency. Lastly, we continued collaborative research assessing how stem hydraulics give insight into drought tolerance mechanisms in nursery crops and be used to develop informed irrigation practices. In support of Sub-objective 3.C.2, we continued a trial to evaluate the effects of irrigation frequency (pulse length) and number of wetting points (number and distribution of emitters per pot) on growth, mineral nutrition, yield, and fruit quality of highbush blueberry in substrate. A subset of plants from each treatment were harvested at the end of second growing season and analyzed for total shoot dry weight, root development, and nutrients in the leaves and stems. Fruit was also harvested and analyzed for size, firmness, soluble solids, and titratable acidity. Yield and total dry weight of the plants were greatest when irrigation was triggered at -2kPa and applied using a new type of multi-outlet drip emitter, which was designed to apply water evenly over the surface of the growing medium and prevent formation of dry spots in the pots. Conversely, root development was greater with two standard emitters/pot when irrigation was triggered at -2 kPa and four standard emitters/pot when irrigation was triggered at -4 kPa. In general, roots were well distributed with four emitters/pot but tended to concentrate between emitters when plants were irrigated with two emitters/pot and concentrate near the soil surface when the plants were irrigated with the multi- outlet emitters. The trial is ongoing and will continue for another year. ACCOMPLISHMENTS 01 Temperature alters biology and fungicide sensitivity of prevalent Phytophthora causing root rot in Rhododendron. Phytophthora root rot causes major losses in nursery crops. There is speculation that increased temperatures from global climate change may increase disease risk from pathogens that thrive under these conditions. ARS researchers in Corvallis, Oregon, conducted a series of experiments to evaluate how temperature affects the biology and control of three soilborne Phytophthora species prevalent in the nursery industry. Our findings help define the temperatures at which these pathogens will be the most damaging and help delineate the temperatures at which fungicides should be applied for maximum efficacy. An important environmental goal for the nursery industry is to reduce environmental impact from chemical treatments; therefore, determining optimal temperatures for fungicide application not only reduces financial costs of production but also decreases environmental impact. 02 Effective mycorrhizal fungi isolates identified among fungi native to vineyard soil. Root symbiotic fungi known as arbuscular mycorrhizal fungi (AMF) are needed for grapevines to grow in soils with limited phosphorus, but grapevines are colonized by numerous species of AMF in the field. An ARS researcher in Corvallis, Oregon, and student at Oregon State University, compared how different native species of AMF promoted growth and nutrient uptake in grapevines. Results showed that two species were superior in promoting vine phosphorus uptake, and one of these also stimulated greater shoot growth than all the other fungi tested. One species did not colonize roots beyond a trace and had no impact on vine performance. Another species promoted greater uptake of manganese than the other fungi. The most effective isolates can be used to create AMF inoculum for specific production needs for vineyards. 03 Fertigation increases potassium in blueberries. Potassium (K), the second most abundant nutrient in plants, is removed in large quantities during harvest, leaf fall, and pruning of perennial fruit crops. ARS researchers in Corvallis, Oregon, investigated different methods of applying K to cultivated blueberries, including fertigation, which is the practice of applying liquid forms of fertilizer through the irrigation water. Work was conducted in a mature blueberry field irrigated by drip. Within one year, fertigation resulted in nearly twice as much K in the soil as the non-fertigated treatments and, as a result, increased K in the shoots and leaves on the plants. Findings from this work indicate that fertigation with K is more effective than applying granular fertilizers and may be useful at sites where leaf and soil K levels are below the recommended range for blueberry. 04 More efficient and sensitive method for detection of the boxwood blight pathogen. Boxwood blight is a serious plant disease affecting the $141 million U.S. boxwood industry. Symptoms of the disease start out as leaf spots and stem lesions and are usually followed by rapid leaf blight and significant defoliation, particularly during wet and warm weather. However, when the weather is dry, the symptoms may be very mild and difficult to detect. As a consequence, a greater number of plants must be screened in order to detect boxwood blight when symptoms are mild. ARS researchers in Corvallis, Oregon, and a researcher at Oregon State University, developed a protocol to extract and amplify the DNA of the boxwood blight pathogen from large amounts of plant tissue. The protocol is specific for the boxwood blight pathogen and is more sensitive than previous methods. This protocol will help detect the pathogen in a large-scale boxwood blight survey being conducted in Oregon nurseries. 05 Inoculating mycorrhizal fungi in vineyards in the Columbia River Basin is not necessary. Grape growers in the arid Columbia River Basin region lack information regarding how to best manage arbuscular mycorrhizal fungi (AMF), including knowing whether or not to inoculate vines when planting or replanting vineyards and what factors may influence AMF in established plantings. ARS researchers in Corvallis, Oregon, and a colleague from Washington State University, examined AMF root colonization, soil and vine nutrient levels, and nematode populations in 32 wine grape vineyards and conducted a seasonal study in a vineyard with high populations of the northern root-knot nematode pest. Results indicated that root colonization by AMF was just as high in one to two year-old vineyards as in much older vineyards. Lower root colonization by AMF was most closely linked to high soil and plant nitrogen levels, and to high levels of the northern root-knot nematode. These findings show that wine grape growers in the region do not need to inoculate vines with AMF when planting or replanting vineyards but should carefully manage nitrogen inputs and control the northern root-knot nematode to ensure healthy and functional AMF in roots. 06 Water footprint of blueberries. A ⿿water footprint, defined as the amount of water necessary to produce a unit of a particular product, is a means to evaluate utilization of freshwater resources for human activities, including agriculture. In collaboration with faculty at the University of Buenos Aires in Argentina and the University of Concepción in Chile, an ARS researcher in Corvallis, Oregon, determined the water footprint for producing blueberries. Three widely grown cultivars were evaluated, including ⿿Star⿿, ⿿Emerald⿿, and ⿿Snowchaser⿿. The annual footprint of each, which included water utilized from rain, drip irrigation, and sprinklers for frost protection, differed among the cultivars and ranged from 25-69 gallons of water to produce a pound of berries in ⿿Star⿿, 35-118 gallons of water to produce a pound of berries in ⿿Emerald⿿, and 64-487 gallons of water to produce a pound of berries in ⿿Snowchaser⿿. ⿿Snowchaser⿿ bloomed at the beginning of winter and therefore required more water for frost protection than ⿿Emerald⿿ and ⿿Star⿿, while ⿿Star⿿ lost most of its leaves during the winter, flowered late, and consequently used the least amount of water among the cultivars. Irrigation designers can use this information to quantify water requirements for each cultivar and allocate water for irrigation and frost protection accordingly. 07 Cool temperatures can increase severity of boxwood blight. Production of boxwood, the most valuable broadleaf evergreen shrub produced by the U.S. nursery industry, is threatened by boxwood blight pathogen, Calonectria pseudonaviculata. The disease is reportedly more severe when environmental conditions are warm, humid, and rainy, yet there is conflicting evidence on the role of temperature and moisture on pathogen biology and disease spread. ARS researchers in Corvallis, Oregon, and a researcher at Oregon State University, determined that Oregon isolates of C. pseudonaviculata are capable of growing faster and causing more severe disease at temperatures cooler than those reported previously. Results are important because they suggest that a lower optimal temperature might need to be included in the current risk model used by industry to predict pathogen infection and in future boxwood blight resistance assays used by researchers and breeders. 08 Irrigation management in nurseries has little impact on root rot control after the pathogen has infected the plant. Phytophthora root rot, causes significant losses in nursery crops, and disease tends to be more severe in heavily irrigated or waterlogged conditions. Altering irrigation management may be useful in developing integrated disease management practices particularly when pathogen populations are low. ARS researchers in Corvallis, Oregon, determined that root rot severity increased when more pathogen was present; however, reducing irrigation did not lessen the amount of root rot. Instead, severe root rot often led to increased soil moisture as the roots became progressively compromised in their ability to take up water. Results are important because they indicate that reducing irrigation after infection has occurred does little to control root rot. Instead, root rot control efforts should focus on preventing infection in the first place. 09 Experimental methods for inducing Phytophthora root rot are representative of nursery conditions. Soil moisture influences how Phytophthora pathogens cause root rot in nurseries. Most research experiments with these pathogens flood the soil of plants in container water to ensure that root rot develops. However, the degree of flooding used in experiments does not usually occur in nurseries where plants are either maintained in containers that can drain freely or they may periodically sit in a shallow pool of water if drainage is poor. ARS researchers in Corvallis, Oregon, and a researcher at Oregon State University, determined that rhododendron root rot was similar in flooded plants in containers and plants irrigated to mimic nursery conditions. These results are important because they ensure that research conditions are representative of the amount of damage that occurs in nurseries. 10 Optimizing fertilizer practices under different irrigation management regimes improves end product quality of Rhododendron nursery plants. Sustainable nursery crop production requires optimization of two major inputs, fertilizer and water, to achieve growers' economic and environmental goals. Achieving these goals requires information on how plants respond to the combined effects of these inputs. ARS researchers in Corvallis, Oregon, and researchers at Mississippi State University, investigated how fertilizer and irrigation management during container production of rhododendron influenced plant growth, flowering, and nutrient uptake after transplanting into the landscape. The results indicate that manipulating fertilizer and irrigation frequency and volume can be used to alter nursery stock qualities and improve subsequent performance in the landscape. Nursery production strategies that improve plant survival, growth, and productivity after transplanting can substantially improve the value of nursery crops. 11 A new model for optimizing irrigation in hazelnuts. Knowing the exact amount of water required by a crop is essential for irrigation planning and for improving the efficiency of irrigation water use. In collaboration with faculty at the University of Concepción in Chile, an ARS researcher in Corvallis, Oregon, developed a new model for estimating the water requirements in hazelnut. The model was evaluated for three growing seasons in orchards irrigated by drip or micro- sprinklers. Results were highly correlated with measurements obtained from nearby weather stations and indicated the model accurately calculated daily and seasonal water use under a variety of growing conditions. This model will be useful for optimizing irrigation in hazelnuts and other perennial cropping systems.
Impacts
(N/A)
Publications
- Leon-Chang, D.P., Bryla, D.R., Scagel, C.F. 2023. Response of northern highbush blueberry to fertigation and granular applications of phosphorus fertilizers. Acta Horticulturae. 1357:51-58. https://doi.org/10.17660/ ActaHortic.2023.1357.8.
- Pannunzio, A., Holzapfel, E., Cirelli, A., Texeria, P., Souto, C., Bryla, D.R. 2023. Agricultural water footprint for southern highbush blueberry produced commercially with drip irrigation and sprinkler frost protection. Agricultural Sciences. 14(1):114-128. https://doi.org/10.4236/as.2023. 141008.
- Leon-Chang, D.P., Bryla, D.R., Scagel, C.F., Strik, B.C. 2022. Influence of fertigation and granular applications of potassium fertilizer on soil pH and availability of potassium and other nutrients in a mature planting of northern highbush blueberry. HortScience. 57(11):1377-1386. https://doi. org/10.21273/HORTSCI16747-22.
- Souto, C., Lagos, O., Holzapfel, E., Ruybal, C., Bryla, D.R., Vidal, G. 2022. Evaluating a surface energy balance model for partially wetted surfaces: Drip and micro-sprinkler systems in hazelnut orchards (Corylus avellana L.). Water. 14(24). Article 4011. https://doi.org/10.3390/ w14244011.
- Scagel, C.F., Weiland, G.E., Beck, B.R., Mitchell, J.N. 2023. Temperature and fungicide sensitivity in three prevalent Phytophthora species causing Phytophthora root rot in rhododendron. Plant Disease. https://doi.org/10. 1094/pdis-11-22-2670-re.
- Schreiner, R.P., Tian, T. 2022. Performance of taxonomically diverse native isolates of mycorrhizal fungi in symbiosis with young grapevines. HortScience. 57(9):1135-1144. https://doi.org/10.21273/HORTSCI16648-22.
- Bi, G., Scagel, C.F., Bryla, D.R. 2022. Nitrogen rate, irrigation frequency and volume differentially influence growth, flowering, and nutrient uptake of container-grown rhododendron during the following growing season. Horticulturae. 8(7). Article 647. https://doi.org/10.3390/ horticulturae8070647.
- Ohkura, M., Scagel, C.F., Weiland, G.E. 2023. Rapid and scalable DNA extraction and real-time PCR assay from boxwood tissue for the detection of Calonectria pseudonaviculata, causal agent of boxwood blight. Plant Disease. 107(5):1279-1283. https://doi.org/10.1094/PDIS-06-22-1453-SR.
- Mestas, A., Weiland, G.E., Scagel, C.F., Davis, E.A., Mitchell, J.N., Beck, B.R. 2023. Greater rate of nitrogen fertilizer application increases root rot caused by Phytophthora cinnamomi and P. plurivora in container-grown rhododendron. Plant Pathology. https://doi.org/10.1111/ppa.13776.
- Schreiner, R.P., Moyer, M.M., East, K.E., Zasada, I.A. 2023. Managing arbuscular mycorrhizal fungi in arid Columbia Basin vineyards of the Pacific Northwest United States. American Journal of Enology and Viticulture. 74(1). Article 074002. https://doi.org/10.5344/ajev.2023. 23005.
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Progress 10/01/21 to 09/30/22
Outputs
PROGRESS REPORT Objectives (from AD-416): Irrigation and nutrient management are key factors that impact sustainable and profitable production of high-quality small fruit and nursery crops. The goal of this project is to develop new approaches that integrate water and nutrient management methods with other environmental and cultural constraints to improve the quantity and quality of berry, wine grape, and nursery crops grown in the Pacific Northwest (PNW) while protecting the environment. Objective 1: Determine requirements for high-quality berry crop production through monitoring and management of water, nutrients, and soil. [NP 305, Component 1, Problem Statement 1B] Subobjective 1A: Adapt and refine remote sensing technology to monitor water and nutrient deficits and determine irrigation and fertilizer needs in berry crops. Subobjective 1B: Assess the feasibility of using deficit or pulsed-drip irrigation to increase water use efficiency and protect regional water quality in berry crops. Subobjective 1C: Develop new fertigation and soil management practices to increase production and fruit quality in blueberry. Objective 2: Develop approaches to manage vineyard canopies, soils, and nutrients for improved grape production, plant health, and fruit quality. [NP 305, Component 1, Problem Statement 1B] Subobjective 2A: Develop an integrated nitrogen (N) management approach encompassing N use in both the vineyard and winery to identify the most effective and efficient manner to manage N inputs to improve wine quality and protect water quality. Subobjective 2B: Examine how canopy architecture, vine density, and crop load interact to identify the most efficient use of sunlight and soil water resources to improve production efficiency of Pinot noir. Subobjective 2C: Understand how N management practices influence beneficial arbuscular mycorrhizal fungi (AMF) in grapevines to develop more sustainable methods for farming grapes. Subobjective 2D: Determine the impact of rootstocks on root development and AMF colonization when challenged by the northern root knot nematode. Objective 3: Evaluate the impact of management practices for water and nutrients on tolerance to abiotic and biotic stress in specialty crops. [NP 305, Component 1, Problem Statement 1C] Subobjective 3A: Develop new management practices and disease control measures to minimize pathogen damage and losses for woody nursery plants. Subobjective 3B: Define salinity thresholds for specialty crops so growers can reduce losses of planting stock, mitigate salinity impacts on quality, and broaden the use of more salt tolerant species in systems considered marginal for production of other crops. Subobjective 3C: Develop and evaluate water and nutrient management practices for specialty crops grown in soilless substrates. Approach (from AD-416): Experiments will be conducted in the greenhouse and field on small fruit (blueberry, raspberry, strawberry, grapevines) and other specialty crops including nursery crops (Rhododendron, Vaccinium, Basil), and in growth chambers on root pathogens. For Obj. 1 we will develop remote sensing based crop coefficients and water stress indices for irrigation of blueberry and raspberry, and will test the following hypotheses: Deficit irrigation will reduce water use but have no effect on yield or fruit quality when it is applied at early stages of fruit development or after harvest in blueberry or raspberry; Pulsed-drip irrigation will reduce water use and increase yield and production relative to conventional irrigation in blueberry and raspberry; Application of P and B by fertigation will result in greater yield and fruit quality than granular or foliar fertilizers in blueberry; Biostimulants are most effective when applied at low rates and during peaks in root production. For Obj. 2 we will test these hypotheses: Maintaining low N status in the vineyard will enhance wine composition as compared to boosting N supply in the vineyard; Varying N supply to Pinot noir alters berry and wine phenolic composition to a greater extent than P or K; Altering the VSP trellis to increase canopy solar exposure at midday will increase productivity but not alter ripening or fruit quality in Pinot noir; Soil and foliar applied N in vineyards reduces AMF colonization and P uptake; Nitrogen inhibition of AMF colonization in grape roots increases with N dose; Nitrogen is a more potent inhibitor of AMF as vine P increases; Root development and AMF colonization differ among rootstock genotypes when northern root knot nematode is present. We will test the following hypotheses for Obj. 3: Critical temperatures for vegetative growth and zoospore formation of Phytophthora isolates will be similar within a species; fungicide sensitivity of Phytophthora is greatest at the optimal temperature for growth; Root rot induced by flooding is more severe than rot under moisture conditions common in nurseries; Reducing water availability minimizes root damage caused by Phytophthora in rhododendron; Increasing N increases root damage caused by Phytophthora in rhododendron; Crop tolerance to salinity will differ among production systems; Southern highbush blueberry plants have different substrate needs than northern highbush blueberry; Strategies to improve water distribution in substrates will increase growth and production in blueberry. Measurements and techniques used in these studies will include standard approaches to measure plant growth, biomass, and yield, plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), fruit quality (refractometry, titratation, HPLC, sensory perception), root production and mycorrhizal colonization (soil cores, microscopy), soil pH and EC, soil water content (TDR, tensiometers), plant and soil nutrients (CNS analyzer, ICP), and pathogen growth (microbiological media) and root damage (visual ratings). We will also utilize multi-spectral cameras and drones to develop new methods to measure plant water status. In support of Sub-objective 1A, research was continued to investigate remote imaging techniques to monitor plant growth and water requirements in blueberry and raspberry. Two years of remote images were collected from commercial fields located throughout Washington state using a low- altitude, unmanned aerial system (UAS or drone) equipped with a multispectral and a thermal imaging camera. The images ae being processed and analyzed for normalized difference vegetation index (NDVI) and canopy temperature. The NDVI images are providing clear information on development of the canopy in the fields and for estimating irrigation needs at each site. Thermal images are also useful, particularly for assessing spatial variability in water status of fields. Growers can also use the images to determine whether they are scheduling irrigations properly or need to add more water to the field. In support of Sub-objective 1B, field trials are in progress to evaluate new practices for reducing irrigation water in berry crops, including deficit irrigation and pulsed drip irrigation. Results to date indicate that deficit irrigation during early stages of fruit development or after harvest had minimal effect on yield or fruit quality in blueberry. Pulsed drip irrigation, on the other hand, increased soil water availability relative to conventional irrigation in raspberry and, by the second year, increased total production by 7%, or 1,230 kilograms per hectare (kg/ha). Production followed a similar trend the following year and increased by 1, 210 kg/ha with pulsing. A similar trial was initiated in a mature, commercial blueberry field. Within the first year of application, pulsing increased yield by 2,200 kg/ha when irrigation was applied at a fixed rate (grower based) and by 3,290 kg/ha when irrigation was scheduled based on daily estimates of crop water use. Higher production was due primarily to greater berry size. Overall, pulsed drip irrigation appears to be a promising method for improving blueberry and raspberry production on light, well-drained soils. In support of Sub-objective 1C1, field trials were conducted to investigate the value of fertigating with phosphorus (P) and boron (B) fertilizer in highbush blueberry. The trials were completed, and manuscripts of the results were prepared. Results indicate that fertigation and granular applications of P fertilizer increased the concentration of P in soil solution within the root zone, but neither had any effect on yield, berry weight, or berry firmness. Questions remain on whether blueberry requires less P than recommended, or if alternative sources or rates of P fertilizer are needed. Leaf B was significantly affected by the fertilizers and within the first year was sufficient with fertigation or foliar applications, but low in the granular treatments and no different than those with no B. Applying B by fertigation or as a foliar spray appears to be preferable over the use of granular B fertilizers. In support of Sub-objective 1C2, a greenhouse trial was conducted to test the response of highbush blueberry to different rates of humic substances. Six cultivars were chosen for the study, including ⿿Duke⿿, ⿿Draper⿿, ⿿Legacy⿿, ⿿Top Shelf⿿, ⿿Cargo⿿, and ⿿Last Call⿿. Each cultivar was grown in a complete nutrient solution with four rates of organic acids. While dry weight differed among the cultivars, humic substance increased shoot dry weight by an average of 33% and 38% in each cultivar when plants were grown with 250 and 500 mg·L-1 active ingredient (a.i.), respectively, but had no effect on shoot dry weight at a lower rate or on root dry weight at any rate. In support of Sub-objective 2A1, field treatments with varying nitrogen were applied with grower collaborators, and vine growth, nutrient status in leaf blades and petioles, vine water status and gas exchange measurements were completed. Crop yield parameters were measured, and fruit was harvested and delivered to collaborators to make wine and monitor fermentations. Sensory analysis was completed by collaborators. For Sub-objective 2A2, spectral analysis to characterize broad groups of phenolics was completed. In support of Sub-objective 2B, first-year field data were collected for soil moisture profiles, plant growth and yield, and vine water status. We also tested and began using a solar panel device with similarity to the ⿿Paso panel⿿ to measure sunlight interception and showed that this approach distinguished between the main plot canopy width treatments. In addition, numerous measurements of gas exchange were made over the season and these data were compared with other new project sites where we have been trying to estimate how much shaded leaves close stomates compared to leaves in the sun, and how much these shaded leaves may contribute to vine transpiration with little carbon gain. We also collected data on fruit quality metrics including brix, pH, titratable acids, and mineral nutrient levels in musts. In support of Sub-objective 2C1, root samples were collected, cleared, and stained for mycorrhizal colonization assays, and nutrient status of the vines was determined. Work that was planned for Sub-objective 2C2 was discontinued since our results last year showed that young vines grown in the greenhouse did not respond similarly to the field-grown vines to added soil versus foliar nitrogen applications. Therefore, a new line of inquiry and a new method to test how mycorrhizal fungi may influence nitrogen uptake was developed and a preliminary greenhouse experiment was begun to test our methods. This research involved building polyvinyl chloride (PVC) chambers with access holes and the use of different nylon or fiberglass mesh sizes to either allow roots access to nitrogen in the chambers or only mycorrhizal hyphae to gain access to nitrogen. The plants are currently being grown using this new system to see if the mesh and chamber system works as designed. In addition, we began preparing grass residues labeled with heavy nitrogen so that we can trace root and mycorrhizal nitrogen uptake from both inorganic and organic forms when placed in soil. In support of Sub-objective 2D, all the field, root and mycorrhizal data were analyzed, and a portion of the results have been published. A draft manuscript of the remaining results from this work was prepared and is currently being reviewed by co-authors of the project. In support of Sub-objective 3A, research evaluating factors altering horticultural crop root health continued as planned. Collaborative research identifying how temperature alters pathogenicity in the boxwood blight pathogen (Calonectria pseudonaviculata) is complete. Collaborative research continues to evaluate effects of irrigation and plant spacing on spread of the boxwood blight pathogen. Collaborative research also continues to establish how pathogens associated with root rot in nursery plants differ in sensitivity to fungicides and on improving methods for producing reliable inoculum of root rot pathogens. In support of Sub-objectives 3A1 and 3A2, research continued to establish critical temperatures for growth, reproduction, and fungicide sensitivity of pathogens associated with root rot in nursery crops. Trials which identified optimal, minimum, and maximum temperatures for growth and zoospore formation are complete. ARS researchers analyzed data from growth sporulation studies and starting trials to assess temperature effects on fungicide sensitivity. In support of Sub-objective 3A3, research continued to identify how substrate moisture alters the incidence and severity of root rot in nursery crops. Trials which identified whether research techniques used in studying root rot are representative of what occurs under nursery conditions are complete. ARS researchers analyzed data, wrote a manuscript, and published results. In support of Sub-objective 3A4, the researchers completed trials to assess whether irrigation practices that reduce water availability can alter disease, analyzed data, and are currently writing a manuscript. In support of Sub-objective 3B, ARS researchers initiated a trial evaluating effects of salinity on growth and quality of basil grown in different production systems. They collected and analyzed pathological and physiological data and continued collaborative research quantifying fertilizer run-off from nursery crops and use of remote imaging for management of nursery plant nutrition and irrigation. Collaborative research developing techniques to assess drought tolerance mechanisms in nursery crops was initiated. In support of Sub-objective 3C2, a trial was initiated to evaluate the effects of irrigation frequency (pulse length) and number of wetting points (number and distribution of emitters per pot) on growth, mineral nutrition, yield, and fruit quality of highbush blueberry in substrate. A subset of plants from each treatment were harvested destructively at the end of first growing season and analyzed for total shoot dry weight, root development, and nutrients in the leaves and stems. Leachate pH and electrical conductivity were also measured and used to monitor salt accumulation and to make adjustments to the fertilizers. Plants were cropped in year two, and fruit were harvested and analyzed for fruit size, firmness, soluble solids, and titratable acidity. The trial is ongoing and will continue for at least one more year. ACCOMPLISHMENTS 01 Nitrogen fertilization in the vineyard produces unique wines and boosts productivity in Chardonnay. Nitrogen is a key nutrient to manage in both the vineyard and winery because it alters vine productivity and influences wine quality by altering yeast metabolism. Nitrogen is often added in the winery when berry nitrogen is low to ensure successful fermentation, which is assuming that winery nitrogen addition produces the same type of wine as compared to fertilizing the vineyard. ARS researchers in Corvallis, Oregon, and researchers at Oregon State University, tested whether vineyard nitrogen fertilization using either soil or foliar applications would produce similar wines as adding nitrogen in the winery over three growing seasons. Boosting fruit nitrogen by fertilizing the soil produced the most unique wines with greater tropical fruit aromas, while adding nitrogen in the winery did not result in a similar wine, even if fruit nitrogen levels and fermentation rates were similar. The researchers also showed that soil fertilization with nitrogen increased vine growth and yield, but foliar nitrogen did not increase vine productivity. These findings allow grape growers and winemakers to better manage nitrogen inputs in the whole wine production system to produce the desired style of wine and maintain or increase vine productivity. 02 Biochar improves growth and fruit production in blueberry. Blueberry fields are often amended with bark or sawdust prior to planting, but many growers are seeking alternatives because cost of these materials has increased considerably in recent years. One possibility is to use biochar, a carbon-rich material produced by burning wood or other biomass under low oxygen conditions. ARS researchers in Corvallis, Oregon, and collaborators at Oregon State University, determined that amending the soil with biochar nearly doubled blueberry plant growth and fruit production while reducing costs by more than $500 per acre over the usual practice of incorporating sawdust into planting beds. The biochar used in the study was manufactured from mixed conifers during conversion of wood debris to bioenergy at a 30 megawatt power plant. These findings indicate that using biochar as soil amendment is not only cost-effective but a good way to improve soil health and increase early returns in blueberry. 03 Optimizing inoculum production methods for infesting soil with Phytophthora species that cause root rot in nursery plants. Phytophthora root rot causes significant losses in many horticultural crops and research on this pathogen requires consistent and predictable production of viable pathogen inoculum. A common method used to produce inoculum of this pathogen can take six weeks to produce and often results in variability among batches of inoculum that can waste valuable resources and delay research progress. ARS researchers in Corvallis, Oregon, identified inoculum moisture content that reduces inoculum viability and used results to develop a new method that produces more reliable inoculum in a shorter time. This research is important to other researchers because it helps explain variability in soilborne Phytophthora inoculum production and storage and provides a new method for producing inoculum more quickly. 04 Salinity damage depends on the source of the salt in blueberry. Excess salinity is a common problem for production of blueberries in arid and semiarid regions. Options to reduce salinity are available, but information on how it limits the plants is needed. ARS researchers in Corvallis, Oregon, and collaborators at Oregon State University, examined ion-specific effects of different salts on plant growth in blueberry and identified thresholds for salinity damage from sodium chloride and calcium chloride, both of which can be prevalent in soils and irrigation water. They determined that sodium chloride reduced growth more than calcium chloride, while calcium chloride resulted in greater leaf damage due to toxic levels of calcium in the tissue. Results from this research will be useful for developing better salinity management practices for commercial blueberry production. 05 Grapevine rootstocks reduce the establishment of the northern root-knot nematode in new vineyards. Plant-parasitic nematodes, microscopic roundworms, feed on the roots of grapevines and can reduce vine productivity and fruit quality. These pests are difficult to control and new control methods are needed. ARS researchers from Corvallis, Oregon, and researchers from Washington State University, examined whether reducing irrigation water applied to a young vineyard or the use of different rootstocks could reduce the numbers of the root-knot nematode. Modifying irrigation practices did not reduce the number of nematodes in grape roots or soils, but growing rootstocks was an effective way to control this nematode pest. These findings will be used by grape growers to aid in plant selection at planting to minimize the impact of nematodes on vine productivity. 06 Experimental methods for inducing Phytophthora root rot that are representative of nursery conditions. Soil moisture influences how Phytophthora pathogens cause root rot in nurseries. Most research experiments with these pathogens flood the soil of plants in containers with water to ensure that root rot develops. However, the degree of flooding used in experiments does not usually occur in nurseries where plants are either maintained in containers that can drain freely or they may periodically sit in a shallow pool of water if drainage is poor. ARS researchers in Corvallis, Oregon, and researchers at Oregon State University, determined that rhododendron root rot was similar in flooded plants in containers as in plants irrigated to mimic different nursery conditions. These results show that prior research using flooding to induce Phytopthera root rot is representative of the amount of damage caused by this pathogen that can occur under actual nursery conditions. 07 Several Phytophthora species cause rhododendron root rot in nurseries. Rhododendrons are an important component of the ornamental nursery industry, but are prone to Phytophthora root rot, despite decades of research. One Phytophthora species, P. cinnamomi, was previously thought to be the primary pathogen causing rhododendron root rot, and although recent research suggests there are several other Phytophthora species that may cause root rot, little is known of their virulence and risk to the industry. ARS researchers in Corvallis, Oregon, and researchers at Oregon State University, determined that at least three other Phytophthora species isolated from Oregon nursery plants can cause similar disease severity as P. cinnamomi, but not all species are equally virulent. This research provides valuable information for other researchers and industry in developing more effective disease control measures. 08 Cool temperatures can increase severity of boxwood blight. Production of boxwood, the most valuable broadleaf evergreen shrub produced by the U.S. nursery industry, is threatened by boxwood blight pathogen, Calonectria pseudonaviculata. The disease is reportedly more severe when environmental conditions are warm, humid, and rainy, yet there is conflicting evidence on the role of temperature and moisture on pathogen biology and disease spread. ARS researchers in Corvallis, Oregon, and researchers at Oregon State University, determined that Oregon isolates of C. pseudonaviculata can grow faster and cause more severe disease at cooler temperatures than those reported previously. Results are important because they suggest that a lower optimal temperature should be included in the current risk model used by industry to predict pathogen infection and in future boxwood blight resistance assays used by researchers and breeders. 09 Irrigation management in nurseries has little impact on root rot control after the pathogen has infected the plant. Phytophthora root rot causes significant losses in nursery crops, and disease tends to be more severe in heavily irrigated or waterlogged conditions. Altering irrigation may be useful in developing integrated disease management practices, particularly when pathogen populations are low. ARS researchers in Corvallis, Oregon, determined that root rot severity increased when more pathogen was present; however, reducing irrigation did not lessen the amount of root rot. Instead, severe root rot often led to increased soil moisture as the roots became progressively compromised in their ability to take up water. Results are important to growers because they indicate that reducing irrigation after infection has occurred does little to control root rot. Instead, root rot control efforts should focus on preventing initial infections.
Impacts
(N/A)
Publications
- Sales, B.K., Bryla, D.R., Trippe, K.M., Scagel, C.F., Strik, B.C., Sullivan, D.M. 2022. Biochar as an alternative soil amendment for establishment of northern highbush blueberry. HortScience. 57(2):277-285. https://doi.org/10.21273/HORTSCI16257-21.
- Bryla, D.R., Scagel, C.F., Lukas, S.B., Sullivan, D.M. 2021. Ion-specific limitations of sodium chloride and calcium chloride on growth, nutrient uptake, and mycorrhizal colonization in northern and southern highbush blueberry. Journal of the American Society for Horticultural Science. 146(6):399-410. https://doi.org/10.21273/JASHS05084-21.
- Prado-Tarango, D.E., Mata-Gonzalez, R., Hovland, M., Schreiner, R.P. 2021. Assessing commercial and early-seral arbuscular mycorrhizal fungi inoculation to aid in restoring sagebrush steppe shrubs. Rangeland Ecology and Management. 79:87-90. https://doi.org/10.1016/j.rama.2021.08.001.
- Mestas, A., Weiland, G.E., Scagel, C.F., Grunwald, N.J., Davis, E.A., Mitchell, J.N., Beck, B.R. 2022. Is disease induced by flooding representative of nursery conditions in rhododendrons infected with P. cinnamomi or P. plurivora? Plant Disease. 106(4):1157-1166. https://doi. org/10.1094/PDIS-06-21-1340-RE.
- Weiland, G.E., Ohkura, M., Scagel, C.F., Davis, E.A., Beck, B.R. 2022. Cool temperatures favor growth of Oregon isolates of Calonectria pseudonaviculata and increase severity of boxwood blight on two Buxus cultivars. Plant Disease. https://doi.org/10.1094/PDIS-04-22-0769-RE.
- East, K.E., Zasada, I.A., Schreiner, R.P., Moyer, M.M. 2021. Irrigation and rootstocks to manage northern root-knot nematode during wine grape vineyard establishment. Plant Health Progress. 23(1):49-56. https://doi. org/10.1094/PHP-06-21-0097-RS.
- Tian, T., Ruppel, M., Osborne, J., Tomasino, E., Schreiner, R.P. 2022. Fertilize or supplement: The impact of nitrogen on vine productivity and wine sensory properties in Chardonnay. American Journal of Enology and Viticulture. 73(3):148-161. https://doi.org/10.5344/ajev.2022.21044.
- Weiland, G.E., Scagel, C.F., Grunwald, N.J., Davis, E.A., Beck, B.R., Mitchell, J.N. 2022. Irrigation frequency and volume has little influence on Phytophthora root rot in container-grown rhododendron. Journal of Environmental Horticulture. 40(2):67-78. https://doi.org/10.24266/2573- 5586-40.2.67.
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Progress 10/01/20 to 09/30/21
Outputs
PROGRESS REPORT Objectives (from AD-416): Irrigation and nutrient management are key factors that impact sustainable and profitable production of high-quality small fruit and nursery crops. The goal of this project is to develop new approaches that integrate water and nutrient management methods with other environmental and cultural constraints to improve the quantity and quality of berry, wine grape, and nursery crops grown in the Pacific Northwest (PNW) while protecting the environment. Objective 1: Determine requirements for high-quality berry crop production through monitoring and management of water, nutrients, and soil. [NP 305, Component 1, Problem Statement 1B] Subobjective 1A: Adapt and refine remote sensing technology to monitor water and nutrient deficits and determine irrigation and fertilizer needs in berry crops. Subobjective 1B: Assess the feasibility of using deficit or pulsed-drip irrigation to increase water use efficiency and protect regional water quality in berry crops. Subobjective 1C: Develop new fertigation and soil management practices to increase production and fruit quality in blueberry. Objective 2: Develop approaches to manage vineyard canopies, soils, and nutrients for improved grape production, plant health, and fruit quality. [NP 305, Component 1, Problem Statement 1B] Subobjective 2A: Develop an integrated nitrogen (N) management approach encompassing N use in both the vineyard and winery to identify the most effective and efficient manner to manage N inputs to improve wine quality and protect water quality. Subobjective 2B: Examine how canopy architecture, vine density, and crop load interact to identify the most efficient use of sunlight and soil water resources to improve production efficiency of Pinot noir. Subobjective 2C: Understand how N management practices influence beneficial arbuscular mycorrhizal fungi (AMF) in grapevines to develop more sustainable methods for farming grapes. Subobjective 2D: Determine the impact of rootstocks on root development and AMF colonization when challenged by the northern root knot nematode. Objective 3: Evaluate the impact of management practices for water and nutrients on tolerance to abiotic and biotic stress in specialty crops. [NP 305, Component 1, Problem Statement 1C] Subobjective 3A: Develop new management practices and disease control measures to minimize pathogen damage and losses for woody nursery plants. Subobjective 3B: Define salinity thresholds for specialty crops so growers can reduce losses of planting stock, mitigate salinity impacts on quality, and broaden the use of more salt tolerant species in systems considered marginal for production of other crops. Subobjective 3C: Develop and evaluate water and nutrient management practices for specialty crops grown in soilless substrates. Approach (from AD-416): Experiments will be conducted in the greenhouse and field on small fruit (blueberry, raspberry, strawberry, grapevines) and other specialty crops including nursery crops (Rhododendron, Vaccinium, Basil), and in growth chambers on root pathogens. For Obj. 1 we will develop remote sensing based crop coefficients and water stress indices for irrigation of blueberry and raspberry, and will test the following hypotheses: Deficit irrigation will reduce water use but have no effect on yield or fruit quality when it is applied at early stages of fruit development or after harvest in blueberry or raspberry; Pulsed-drip irrigation will reduce water use and increase yield and production relative to conventional irrigation in blueberry and raspberry; Application of P and B by fertigation will result in greater yield and fruit quality than granular or foliar fertilizers in blueberry; Biostimulants are most effective when applied at low rates and during peaks in root production. For Obj. 2 we will test these hypotheses: Maintaining low N status in the vineyard will enhance wine composition as compared to boosting N supply in the vineyard; Varying N supply to Pinot noir alters berry and wine phenolic composition to a greater extent than P or K; Altering the VSP trellis to increase canopy solar exposure at midday will increase productivity but not alter ripening or fruit quality in Pinot noir; Soil and foliar applied N in vineyards reduces AMF colonization and P uptake; Nitrogen inhibition of AMF colonization in grape roots increases with N dose; Nitrogen is a more potent inhibitor of AMF as vine P increases; Root development and AMF colonization differ among rootstock genotypes when northern root knot nematode is present. We will test the following hypotheses for Obj. 3: Critical temperatures for vegetative growth and zoospore formation of Phytophthora isolates will be similar within a species; fungicide sensitivity of Phytophthora is greatest at the optimal temperature for growth; Root rot induced by flooding is more severe than rot under moisture conditions common in nurseries; Reducing water availability minimizes root damage caused by Phytophthora in rhododendron; Increasing N increases root damage caused by Phytophthora in rhododendron; Crop tolerance to salinity will differ among production systems; Southern highbush blueberry plants have different substrate needs than northern highbush blueberry; Strategies to improve water distribution in substrates will increase growth and production in blueberry. Measurements and techniques used in these studies will include standard approaches to measure plant growth, biomass, and yield, plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), fruit quality (refractometry, titratation, HPLC, sensory perception), root production and mycorrhizal colonization (soil cores, microscopy), soil pH and EC, soil water content (TDR, tensiometers), plant and soil nutrients (CNS analyzer, ICP), and pathogen growth (microbiological media) and root damage (visual ratings). We will also utilize multi-spectral cameras and drones to develop new methods to measure plant water status. Research was continued in support of Sub-objective 1A, to investigate new remote imaging techniques for assessing the need for irrigation in blueberry and raspberry and to better prepare each industry against future water uncertainties. Two years of remote images were collected at least monthly from commercial field sites located throughout Washington State using a low-altitude, unmanned aerial system (UAS or drone) equipped with a multispectral and a thermal imaging camera. The images were processed and analyzed for normalized difference vegetation index (NDVI) and canopy temperature. While physiologically-based indicators can only be measured in a limited number of plants, remote imagery collected with the UAS was a quick and easy method to provide information on every plant on the farm. Fields were mapped on a block-by-block basis, providing an invaluable tool for water management. The NDVI images provided clear information on development of the canopy in the fields and to estimate the irrigation needs at each site. Thermal images were also useful, particularly for assessing spatial variability in water status of the fields. For example, thermal imaging revealed that large sections of a 4.5-ha field were under-irrigated. Although there was no visual evidence of drought stress in these plants (i.e., no wilting), it turned out that many of the drip emitters located in the under-irrigated sections were plugged. Such information enables growers to quickly identify problems with their irrigation systems. Growers can also use the images to determine whether they are scheduling irrigations properly or need to add more water to the field. Field trials were continued in support of Sub-objective 1B, in order to evaluate new practices for reducing irrigation water use in berry crops, including deficit irrigation and pulsed drip irrigation. Results indicated that reducing irrigation during early stages of fruit development or after harvest has minimal effect on yield or fruit quality in blueberry. Applying irrigation in a series of small pulses, on the other hand, increased soil water availability relative to conventional irrigation in raspberry and, by the second year, increased total production by 7%, or 1230 kg/ha. Production followed a similar trend in the following year and increased by 1209 kg/ha with pulsing. Based on recent market prices for processed raspberries, the increase in production with pulsed drip was equivalent to $2,460/ha per year. Much of this increase occurred during the latter three to four weeks of the harvest season and was primarily due to larger fruit size with pulsing in year two and to more berries per plant in year three. Pulsed drip also increased canopy cover by nearly 12% in year two and resulted in larger and more floricanes per plant in year three. Based on these results, pulsed drip irrigation appears to be a promising method for improving production of red raspberries. A similar trial was initiated this year in blueberry. Use of deficit irrigation would lead to immediate water savings, and when coupled with remote sensing technology, could enable growers and irrigation managers to optimize on-farm and regional water use. When managed properly, pulsing could increase plant growth and production relative to applying water all at once each day or two and can greatly reduce runoff, evaporation, and leaching. In support of Sub-objective 1C, trials investigating the value of fertigating with phosphorus (P) and boron (B) fertilizer in highbush blueberry were continued. Results indicate that fertigation and granular applications of P fertilizer increased the concentration of P in soil solution within the root zone, but neither had any effect on yield, berry weight, or berry firmness in either cultivar. These treatments also had no effect on leaf P. In fact, the concentration of P in the leaves was no different than it was prior to applying any P to the plants; however, granular P increased the concentration of P in the roots of both cultivars and tended to reduce root colonization by mycorrhizal fungi in ⿿Bluecrop⿿. The soil at the site was high in clay and likely bound much of the applied P. Questions remain on whether blueberry requires less P than recommended or if alternative sources or rates of P fertilizer are needed. Leaf B, on the other hand, was significantly affected by the fertilizers and within the first year was sufficient with fertigation or foliar applications but low in the granular treatments and no different than those with no B. By the following year, leaf B remained low in treatments with no B and in one cultivar remained deficient with granular B. At this point, applying B by fertigation or as a foliar appears to be preferable over the use of granular B fertilizers. The project builds on our previous work on nitrogen and potassium and will be used to develop complete guidelines for fertigation of highbush blueberry. The results will help growers improve production in the crop and enhance fruit quality for consumers. A trial was initiated in support of Sub-objective 1C, to assess the response of blueberry to biostimulants and ascertain how they function in new and mature plantings. Several different biostimulants were tested, including humic substances (humic and fulvic acids), extracts from Ascophyllum seaweed, and a mix of nitrogen-fixing bacteria (Azorhizobium caulinodans, Azoarcus indigens, and Azospirillium brasiliense). Fertigating with humic substances or seaweed extract increased growth of the plants relative to using the bacterial mix or nutrients only; however, the response was quite different between the two products. Plants grown with humic substances were greener and contained more N than those in the other treatments, while those grown with seaweed extract tended to be taller and more upright. Clearly, the use of these products can be beneficial during establishment of highbush blueberry, but more research is needed to determine exactly how they work and whether they are useful under all circumstances. In support of Sub-objective 2A, field treatments with varying nitrogen were applied with grower collaborators and vine growth, nutrient status in leaf and petioles, water status and gas exchange measurements were completed. Crop yield parameters were measured and fruit was harvested and delivered to collaborators to make wine and monitor fermentations. Sensory analysis was completed by collaborators. Also in support of Sub- objective 2A, the first steps of spectral analysis on both berries and wines were completed. In support of Sub-objective 2B, the baseline data was collected for soil moisture profiles, plant growth and yield, and water status. However, due to poor fruit set resulting from cool rainy weather at bloom, crop load was well below normal. In support of Sub-objective 2C, all root samples were collected and cleared and stained for mycorrhizal colonization assays and nutrient status for the vines was determined. Research to evaluate the impact of soil and foliar nitrogen on mycorrhizal fungi and plant nutrition in controlled greenhouse conditions was conducted to further support Sub- objective 2C. Results showed that young vines did not respond in a similar fashion as older field-grown vines to added nitrogen and root colonization by mycorrhizal fungi was unaffected by nitrogen supplied to the soil or to the foliage. In support of Sub-objective 2D, root samples were processed, root parameters were measured and roots were cleared and stained for mycorrhizal assays. In support of Sub-objective 3A, research continued on establishing critical temperatures for growth, reproduction, and fungicide sensitivity of pathogens associated with root rot in nursery crops. Completed trials identified optimal, minimum, and maximum temperatures for growth. Researchers are currently analyzing data from growth studies and starting trials to assess temperature effects on pathogen reproduction and fungicide sensitivity. In further support of Sub-objective 3A, research continued to identify how substrate moisture alters the incidence and severity of root rot in nursery crops. Completed trials identified whether research techniques used in studying root rot are representative of what occurs under nursery conditions. Researchers are currently analyzing data and writing a manuscript and starting trials to assess whether irrigation practices that reduce water availability can alter disease. In general support of Sub-objective 3A, research evaluating factors altering horticultural crop root health continued as planned. Collaborative research was completed on numerous projects, including: identifying how temperature and moisture alter pathogenicity in raspberry root rot; comparing virulence of multiple pathogens associated with root rot in nursery grown Rhododendron; establishing how pathogens associated with root rot in nursery plants differ in sensitivity to fungicides; and improving methods for producing reliable inoculum of root rot pathogens. Collaborative research continued on quantifying fertilizer run-off from nursery crops and use of remote imaging for management of nursery plant nutrition and irrigation and evaluating environmental effects on spread of the boxwood blight pathogen. Researchers initiated a trial in support of Sub-objective 3C to evaluate the effects of irrigation frequency (pulse length) and number of wetting points (number and distribution of emitters per pot) on growth, mineral nutrition, yield, and fruit quality of highbush blueberry in substrate. The study will provide new information on best irrigation practices for substrate production of blueberries and ultimately contribute to the feasibility of using this type of niche production. Record of Any Impact of Maximized Teleworking Requirement: The laboratory⿿s maximized telework posture decreased our project⿿s ability to make progress towards future milestones, including travel to out-of-state sites for Objective 1. It will now be difficult to substantially complete several milestones for 2022. Maximized telework posture provided more time to analyze data and work on manuscripts, but decreased our productivity and ability to explore new research areas. ACCOMPLISHMENTS 01 Variability in fungicide sensitivity and Phytophthora root rot in rhododendron nursery plants. Fungicides used by growers frequently fail to control Phytophthora root rot in rhododendron nursery plants, causing significant losses to the $42 million industry. ARS researchers in Corvallis, Oregon, determined three reasons why fungicide control of this disease might fail: (i) the fungicide is applied to the wrong portion of the plant for optimal control; (ii) there are differences in fungicide sensitivity among the many different soilborne Phytophthora spp. and isolates infecting rhododendron; and (iii) fungicide- insensitive isolates are present in the rhododendron nursery industry. This research provides valuable information for other researchers and industry in developing more effective disease control measures. 02 New guidelines extend the time window to monitor water stress in grapevines. The pressure chamber is the standard tool used to measure water stress in vineyards and other crops, but its application was limited by the one-hour time period when measurements were thought to reflect the maximal level of vine water stress experienced during the day. An ARS researcher in Corvallis, Oregon, and a graduate student from Oregon State University, evaluated when different measures obtained with the pressure chamber were stable at the maximal daily stress level in vineyards utilizing north-south oriented, vertical shoot positioning (VSP) trellis systems. The VSP system with north- south oriented rows is the most common training system used in wine grapes worldwide. Results obtained from multiple vineyards and a variety of conditions revealed that leaf water potential accurately reflected the maximal level of water stress for up to a four-hour time period beginning at solar noon in vineyards employing VSP systems. These findings are being utilized by researchers and growers to increase the number of vines or vineyard blocks that are monitored on a given day to improve sustainable water use in vineyards. 03 A new tool for preventing heat damage in blueberries. Heat damage is a persistent problem in blueberries and results in millions of dollars of fruit loss each year. Growers commonly report sunburn, softening, and discoloration of the berries when temperatures exceed 90 to 95 degrees Fahrenheit. An ARS researcher in Corvallis, Oregon, and collaborators from Oregon State University, and Washington State University determined that sprinkler irrigation was very effective at reducing heat damage and developed a model to identify the best time and frequency to operate these systems for cooling. This model is a valuable new tool that will help protect the blueberry industry against costly fruit losses during hot weather. 04 Strategies for dealing with drought in blueberries. Many blueberry growers are facing serious water limitations due to drought and increased demand for water by other sectors, and must often cut back on irrigation during drier years. To identify periods in which irrigation may be less critical for blueberries, an ARS researcher in Corvallis, Oregon, and collaborators from Oregon State University, evaluated the effects of soil water deficits during fruit development in a wide range of blueberry cultivars that ripen at various times between June and September. Water deficits applied during later stages of fruit development had the largest effects, particularly in cultivars that ripened later, but was less critical during early stages of fruit development, suggesting this may be a good time to reduce irrigation if needed. Results from the study will help blueberry growers increase the efficiency of irrigation water use and reduce losses of yield and fruit quality in years when water is limited. 05 New tissue nutrient test shows promise in grapevines. Grape growers use leaf blades, or petioles, collected during the growing season to diagnose vine nutritional status, but an earlier indicator of vine nutrient status is desired to give growers enough time to develop more efficient nutrient management plans for the year. An ARS researcher in Corvallis, Oregon, tested if dormant season pruning wood collected in the winter over four years could predict vine nutrient status in the subsequent growing season, as measured in leaf blades and petioles at bloom and veraison (when grapes turn red). Winter time pruning wood was an excellent predictor of vine phosphorus levels and a good predictor of potassium levels during the next growing season, but the winter samples were not effective in predicting vine nitrogen status. These promising results will be further tested as part of a nationwide study to find new tools for grape producers to better monitor nutrition. 06 Several Phytophthora species cause rhododendron root rot in nurseries. Rhododendrons are an important component of the ornamental nursery industry, but are prone to Phytophthora root rot, despite decades of research. One Phytophthora species, P. cinnamomi, was previously thought to be the primary pathogen causing rhododendron root rot. Recent research suggests there are several other Phytophthora species that may cause root rot, but little was known of their virulence and risk to the industry. ARS researchers in Corvallis, Oregon, and researchers at Oregon State University, determined that at least three other Phytophthora species isolated from Oregon nursery plants can cause similar disease severity as P. cinnamomic, but not all species are equally virulent. This research provides valuable information for other researchers and industry in developing more effective disease control measures. 07 Transport of nitrate from roots to shoots drives the growth promoting ability of grapevine rootstocks. Grapevine rootstocks are used in viticulture to control pests and also vine growth or size, which is related to their ability to both acquire nitrogen from soil and to transport it to the shoot. However, which of these two major mechanisms actually governs nitrogen accumulation in shoots is not understood. An ARS researcher in Corvallis, Oregon, and colleagues from Oregon State University, investigated nitrogen uptake and transport properties of two rootstocks that are known to differ in how well they promote scion growth in a series of studies in grafted Pinot noir grapevines. The results showed that the rootstock known to impart greater scion growth transported more nitrate to leaves resulting from greater water movement to individual leaves under low and high nitrate supply, while the less vigorous rootstock had greater root nitrate uptake capacity and allocated more biomass to roots when nitrogen was low. These findings indicate that growth promotion of scions by grapevine rootstocks appear to result from greater transport of nitrogen to shoots in the xylem as compared to greater uptake kinetics from soil. 08 Understanding optimal temperatures for occurrence of Raspberry root rot. The pathogen, Phytophthora rubi, causes significant losses to root rot in the Washington State red raspberry industry. This pathogen was previously assumed to be the most infective during winter when soil temperatures range from 5 to 10 C. However, recent research has reported that symptoms of root disease during summer were strongly associated with P. rubi. ARS researchers in Corvallis, Oregon, and researchers at Oregon State University, determined that P. rubi grew fastest and sporulated more heavily at 20 C than lower temperatures, but disease severity was similar at 15 and 20 C. These results indicate that P. rubi is more likely to infect during the spring and summer in this region when soil temperatures are between 15 to 20 C. This research provides valuable information for researchers and industry for timing effective disease control measures when the pathogen is most active. 09 Rethinking the use of mulch in blueberries. Many growers are using woven polypropylene ground cover, which is often referred to as ⿿weed mat, in commercial blueberry fields. Weed mat is very cost effective for weed control, but, unlike the previous industry standard of using sawdust mulch, it leads to a reduction in soil health and fruit production within a few years after planting. An ARS researcher in Corvallis, Oregon, and collaborators from Oregon State University, evaluated the potential of using a dual system, in which sawdust is placed underneath the weed mat. The dual system helped plant establishment and increased yield by as much as 20% in the second growing season. Furthermore, weed mat protected the sawdust layer from erosion by wind and rain and was more effective for weed control than sawdust alone. Although there is an extra upfront cost to the dual system, net returns are higher once factors such as labor, maintenance, and fruit sales are considered. 10 Optimizing inoculum production methods for infesting soil with Phytophthora species. Phytophthora root rot causes significant losses in many horticultural crops and research on this pathogen requires consistent and predictable production of viable pathogen inoculum. A common method used to produce inoculum of this pathogen can take six weeks to produce and often results in variability among batches of inoculum that can waste valuable resources and delay research progress. ARS researchers in Corvallis, Oregon, identified inoculum moisture content that reduces inoculum viability and used results to develop a new method that produces more reliable inoculum in a shorter time. This research is important to other researchers because it helps explain variability in soilborne Phytophthora inoculum production and storage, and provides a new method for producing inoculum more quickly.
Impacts
(N/A)
Publications
- Tian, T., Schreiner, R.P. 2021. Appropriate time of day to measure leaf and stem water potential in vineyards using vertical shoot positioning. American Journal of Enology and Viticulture. 72(1):64-72. https://doi.org/ 10.5344/ajev.2020.20020.
- Strik, B.C., Davis, A.J., Bryla, D.R. 2020. Individual and combined use of sawdust and weed mat mulch in a new planting of northern highbush blueberry. II. Nutrient uptake and allocation. HortScience. 55(10):1614- 1621. https://doi.org/10.21273/HORTSCI15271-20.
- Yang, F., Bryla, D.R., Peters, T. 2021. An energy balance model for predicting berry temperature and scheduling sprinklers for cooling in northern highbush blueberry. HortScience. 56(4):447-453. https://doi.org/ 10.21273/HORTSCI15459-20.
- Almutairi, K.F., Bryla, D.R., Strik, B.C. 2021. Sensitivity of northern highbush blueberry cultivars to soil water deficits during various stages of fruit development. HortScience. 56(2):154-162. https://doi.org/10.21273/ HORTSCI15493-20.
- Rossdeutsch, L., Schreiner, R.P., Skinkis, P.A., Deluc, L. 2021. Nitrate uptake and transport properties of two grapevine rootstocks with varying vigor. Frontiers in Plant Science. 11. Article 608813. https://doi.org/10. 3389/fpls.2020.608813.
- Yang, F., Bryla, D.R., Orr, S.T., Strik, B.C., Zhao, Y. 2020. Thermal cooling with sprinklers or microsprinklers reduces heat damage and improves fruit quality in northern highbush blueberry. HortScience. 55(8) :1365-1371. https://doi.org/10.21273/HORTSCI15119-20.
- Schreiner, R.P. 2021. Utility of dormant season pruning wood to predict nutrient status of grapevines. Journal of Plant Nutrition. 44(2):238-251. https://doi.org/10.1080/01904167.2020.1806311.
- Strik, B.C., Davis, A.J., Bryla, D.R., Orr, S.T. 2020. Individual and combined use of sawdust and weed mat mulch in a new planting of northern highbush blueberry I. impacts on plant growth and soil and canopy temperature. HortScience. 55(8):1280-1287. https://doi.org/10.21273/ HORTSCI15122-20.
- Sacher, G.O., Scagel, C.F., Davis, E.A., Beck, B.R., Weiland, G.E. 2021. Virulence of five phytophthora species causing rhododendron root rot in Oregon. Plant Disease. https://doi.org/10.1094/PDIS-09-20-1873-RE.
- Graham, K.A., Beck, B.R., Zasada, I.A., Scagel, C.F., Weiland, G.E. 2021. Growth, sporulation, and pathogenicity of the raspberry pathogen phytophthora rubi under different temperature and moisture regimes. Plant Disease. https://doi.org/10.1094/PDIS-09-20-1916-RE.
- Weiland, G.E., Scagel, C.F., Grunwald, N.J., Davis, E.A., Beck, B.R. 2020. Phytophthora species differ in response to phosphorous acid and mefenoxam for the management of phytophthora root rot in rhododendron. Plant Disease. 105:1505-1514. https://doi.org/10.1094/PDIS-09-20-1960-RE.
- Davis, E.A., Weiland, G.E., Scagel, C.F. 2021. Optimizing inoculum production methods for infesting soil with phytophthora species. Plant Disease. https://doi.org/10.1094/PDIS-12-20-2698-RE.
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Progress 10/01/19 to 09/30/20
Outputs
Progress Report Objectives (from AD-416): Irrigation and nutrient management are key factors that impact sustainable and profitable production of high-quality small fruit and nursery crops. The goal of this project is to develop new approaches that integrate water and nutrient management methods with other environmental and cultural constraints to improve the quantity and quality of berry, wine grape, and nursery crops grown in the Pacific Northwest (PNW) while protecting the environment. Objective 1: Determine requirements for high-quality berry crop production through monitoring and management of water, nutrients, and soil. [NP 305, Component 1, Problem Statement 1B] � Subobjective 1A: Adapt and refine remote sensing technology to monitor water and nutrient deficits and determine irrigation and fertilizer needs in berry crops. � Subobjective 1B: Assess the feasibility of using deficit or pulsed-drip irrigation to increase water use efficiency and protect regional water quality in berry crops. � Subobjective 1C: Develop new fertigation and soil management practices to increase production and fruit quality in blueberry. Objective 2: Develop approaches to manage vineyard canopies, soils, and nutrients for improved grape production, plant health, and fruit quality. [NP 305, Component 1, Problem Statement 1B] � Subobjective 2A: Develop an integrated nitrogen (N) management approach encompassing N use in both the vineyard and winery to identify the most effective and efficient manner to manage N inputs to improve wine quality and protect water quality. � Subobjective 2B: Examine how canopy architecture, vine density, and crop load interact to identify the most efficient use of sunlight and soil water resources to improve production efficiency of Pinot noir. � Subobjective 2C: Understand how N management practices influence beneficial arbuscular mycorrhizal fungi (AMF) in grapevines to develop more sustainable methods for farming grapes. � Subobjective 2D: Determine the impact of rootstocks on root development and AMF colonization when challenged by the northern root knot nematode. Objective 3: Evaluate the impact of management practices for water and nutrients on tolerance to abiotic and biotic stress in specialty crops. [NP 305, Component 1, Problem Statement 1C] � Subobjective 3A: Develop new management practices and disease control measures to minimize pathogen damage and losses for woody nursery plants. � Subobjective 3B: Define salinity thresholds for specialty crops so growers can reduce losses of planting stock, mitigate salinity impacts on quality, and broaden the use of more salt tolerant species in systems considered marginal for production of other crops. � Subobjective 3C: Develop and evaluate water and nutrient management practices for specialty crops grown in soilless substrates. Approach (from AD-416): Experiments will be conducted in the greenhouse and field on small fruit (blueberry, raspberry, strawberry, grapevines) and other specialty crops including nursery crops (Rhododendron, Vaccinium, Basil), and in growth chambers on root pathogens. For Obj. 1 we will develop remote sensing based crop coefficients and water stress indices for irrigation of blueberry and raspberry, and will test the following hypotheses: Deficit irrigation will reduce water use but have no effect on yield or fruit quality when it is applied at early stages of fruit development or after harvest in blueberry or raspberry; Pulsed-drip irrigation will reduce water use and increase yield and production relative to conventional irrigation in blueberry and raspberry; Application of P and B by fertigation will result in greater yield and fruit quality than granular or foliar fertilizers in blueberry; Biostimulants are most effective when applied at low rates and during peaks in root production. For Obj. 2 we will test these hypotheses: Maintaining low N status in the vineyard will enhance wine composition as compared to boosting N supply in the vineyard; Varying N supply to Pinot noir alters berry and wine phenolic composition to a greater extent than P or K; Altering the VSP trellis to increase canopy solar exposure at midday will increase productivity but not alter ripening or fruit quality in Pinot noir; Soil and foliar applied N in vineyards reduces AMF colonization and P uptake; Nitrogen inhibition of AMF colonization in grape roots increases with N dose; Nitrogen is a more potent inhibitor of AMF as vine P increases; Root development and AMF colonization differ among rootstock genotypes when northern root knot nematode is present. We will test the following hypotheses for Obj. 3: Critical temperatures for vegetative growth and zoospore formation of Phytophthora isolates will be similar within a species; fungicide sensitivity of Phytophthora is greatest at the optimal temperature for growth; Root rot induced by flooding is more severe than rot under moisture conditions common in nurseries; Reducing water availability minimizes root damage caused by Phytophthora in rhododendron; Increasing N increases root damage caused by Phytophthora in rhododendron; Crop tolerance to salinity will differ among production systems; Southern highbush blueberry plants have different substrate needs than northern highbush blueberry; Strategies to improve water distribution in substrates will increase growth and production in blueberry. Measurements and techniques used in these studies will include standard approaches to measure plant growth, biomass, and yield, plant water status (pressure chamber, porometer), photosynthesis (gas-exchange), fruit quality (refractometry, titratation, HPLC, sensory perception), root production and mycorrhizal colonization (soil cores, microscopy), soil pH and EC, soil water content (TDR, tensiometers), plant and soil nutrients (CNS analyzer, ICP), and pathogen growth (microbiological media) and root damage (visual ratings). We will also utilize multi-spectral cameras and drones to develop new methods to measure plant water status. This report documents progress for project 2072-21000-055-00D, "Water and Nutrient Management for Sustainable Production of Small Fruit and Nursery Crops," which began April 2020 and continues research from project 2072- 21000-053-00D, "Integrated Water and Nutrient Management Systems for Sustainable and High-Quality Production of Temperate Fruit and Nursery Crops." Six commercial field sites were identified in support of Sub-objective 1A, including four fields each of blueberry and raspberry in Washington. Remote images will be collected at each site using a small unmanned aerial system (sUAS) equipped with a multispectral and a thermal imaging camera. Preliminary measurements indicate that the sUAS is capable of capturing 10 acres of imagery in a single 20-minute flight. The images will be used to monitor canopy development and assess spatial variability in water status of the fields. Any problems in the fields, such as plugged drip emitters and Phytophthora root rot, will also be identified. Data will be used to assess the effects of new and existing management practices on crop development and temperature. Four field trials were initiated in support of Sub-objective 1B in order to assess the effects of deficit and pulsed drip irrigation on fruit production and quality in blueberry and raspberry. Plants in the deficit trials will be fully or deficit irrigated (0% and 50% of estimated crop evapotranspiration) for two weeks during the late green stage of fruit development (late June) and after harvest (August). Pulsing has been programmed to operate for 30 min every two hours, up to eight times per day, as needed, while standard irrigation is programmed to operate once a day for up to four hours, as needed, using approximately the same amount of water as applied to the pulsed treatments. In support of Sub-objective 1C, trials investigating the value of fertigating with phosphorus (P) and boron (B) fertilizer in highbush blueberry were continued. P treatments are applied to two cultivars (Duke and Bluecrop) and include no P fertilizer, soil application of granular ammonium phosphate at the highest recommended rate of 67 kg/hectare P, and bi-weekly fertigation from mid-April to late-July with liquid ammonium polyphosphate at total rates of 34 and 67 kg/hectare P per year. B treatments are also applied to two cultivars (Earliblue and Aurora) and include no B fertilizer, soil application of sodium borate (Borax), foliar application of boric acid, and bi-weekly fertigation from mid- April to late-July with boric acid. Each B fertilizer is applied at a total rate of 1.5 kg/hectare B per year. The treatments were initiated in spring 2019 and will continue for at least two years. In support of Sub-objective 2B, vineyard management for a new study to examine how canopy architecture, vine density and crop level alter productivity and quality of Pinot noir was continued. Thus far this season, vines have been fertilized, shoot-thinned, and shoot-positioned two times. This project will provide a large-scale test of whether increasing midday solar capture by opening up the top of the canopy can improve the quantity of fruit produced without compromising quality or long-term vine health. In support of Sub-objective 2C, a new study was initiated to assess how different sources of nitrogen influence fine root growth, mycorrhizal colonization of roots, nitrogen uptake, and whether or not mycorrhizal fungi facilitate nitrogen uptake from organic nitrogen sources in grapevines. Results from prior experiments showed that mycorrhizal fungi did not enhance inorganic nitrogen uptake by grapevines over a range of nitrogen and phosphorus levels, and that vines obtained some nitrogen form the soil organic pool. We are now examining if mycorrhizal fungi will assist in uptake of nitrogen from organic sources and have planted vines and began collecting growth data. Information from these experiments is important in developing sustainable vineyard nutrient management strategies that can take advantage of beneficial mycorrhizal fungi and reduce inputs and potential nutrient losses to the environment. New studies were initiated to evaluate the impact of water and nutrient management practices on the tolerance of nursery crops to withstand abiotic and biotic stresses in support of Sub-objective 3A. Experiments initiated during the last project cycle to understand how the nursery production environment (irrigation, fertilizer, fungicide, and temperature) affects emerging and new pathogens prevalent in the region were continued. Results from these experiments will be used to develop new management practices and disease control strategies to minimize pathogen damage and losses for woody nursery plants. In support of Sub-objective 3B, experiments were continued to define salinity thresholds for specialty crops grown in different production systems. Results from this research will be used by growers to reduce losses of planting stock, mitigate the impact of salinity on quality, and broaden the use of salt tolerant species in environments that are not suitable for production of other crops. Experiments were initiated to evaluate how water and nutrient management practices for specialty crops grown in soilless media in the field in support of Sub-objective 3C. A new study was initiated to evaluate how fertilizer formulation and rate influence nutrient run-off from five different varieties of container-grown plants commonly grown in Pacific Northwest nurseries. Study plants were also used to investigate how remote sensing using unmanned aerial vehicles (UAVs) can be used to detect crop nutritional and water status. Results from this study are being used to modify a similar experiment planned for later in 2020. Results from these experiments will be used to develop nutrient management strategies than minimize nutrient run-off and develop management options for this type of high-value production system.
Impacts
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Publications
- Scagel, C.F., Lee, J. 2020. Salinity sensitivity and mycorrhizal responsiveness of polyphenolics in �Siam Queen� basil grown in soilless substrate. Scientia Horticulturae. 269.
- Kingston, P.H., Scagel, C.F., Bryla, D.R., Strik, B.C. 2020. Influence of perlite in peat- and coir-based media on vegetative growth and mineral nutrition of highbush blueberry. HortScience. 55(5):658-663.
- Weiland, G.E., Scagel, C.F., Grunwald, N.J., Davis, E.A., Beck, B.R., Foster, Z.S., Fieland, V.J. 2020. Soilborne Phytophthora and Pythium diversity from rhododendron in propagation, container, and field production systems of the Pacific Northwest. Plant Disease. 104(6):1841- 1850.
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