EFFECTS OF HERBICIDES AND WEEDS ON YIELD AND FRUIT QUALITY OF RED RASPBERRY AND BLUEBERRY

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1006414
• Project Start Date: Apr 27, 2015
• Project End Date: Jan 16, 2019
• Program Code: [(N/A)]- (N/A)

Recipient Organization
WASHINGTON STATE UNIVERSITY
240 FRENCH ADMINISTRATION BLDG
PULLMAN,WA 99164-0001

Performing Department
Mt. Vernon Res & Ext Unit

Non Technical Summary
Fruit quality of berry crops, especially regarding their content of antioxidant polyphenols, is an area of increasing interest to producers, retailers, and consumers alike. Consumption of berry polyphenols and their resultant bioactivity in the human body has been linked to reduced age-related cellular oxidation, increased nitrous oxide bioavailability, reduced cancer cell proliferation, and control of blood glucose levels, potentially reducing the negative aspects of aging or aiding in the treatment/prevention of cardiovascular disease, cancers, and diabetes. Advertised fruit quality attributes related to health benefits for consumers are also driving much of the observed increase in demand for blueberries and red raspberries. Several factors involved in berry production have been found to result in differing levels of antioxidant compounds in berries, including genetics, fertilizer source and application rate, organic production, type and color of plastic mulches, or combinations of these and other factors. While management activities as practiced by the grower are usually aimed at increasing berry yield, it is clear from these studies that berry quality attributes can also be directly or indirectly affected by many production decisions. These observations lead to the question of whether certain practices used in production of red raspberry and blueberry in the Pacific Northwest (PNW) are negatively impacting fruit quality attributes, or whether there are practices which, if employed, could increase the quality of PNW fruit. One such factor may be use of herbicides. While excessive herbicide application and injury to crops is commonly known to reduce yield, only a single report of herbicide effect on fruit quality has been published. In this study, simulated 2,4-D drift reduced soluble solids, which are associated with fruit sugar levels, of Concord grape. Direct or indirect effects of herbicides on sugar, organic acid, or anthocyanin or other polyphenol antioxidant production has not been adequately addressed. Additionally, it is not known if there are significant fruit quality effects induced by particular weed species growing in competition with berry plants. In a recent study, timing of weeding in raspberry did not affect berry juice pH or °Brix grade. However, the effect of season-long competition with individual perennial weed species was not evaluated in this study, and no analysis of other fruit quality constituents was conducted. If such effects can be identified, control of certain weed species might be considered to be essential or of less importance. Further, if berry quality effects due to perennial weed competition are neutral or positive, grower interest in perennial plants grown as living mulches in berry plantings would increase, offering enhanced annual weed control, while perhaps reducing the cost of berry production through reduced herbicide usage.

Animal Health Component

50%

Research Effort Categories

Basic

50%

Applied

50%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
213	1120	1140	50%
213	1123	1140	50%

Knowledge Area
213 - Weeds Affecting Plants;

Subject Of Investigation
1120 - Blueberry; 1123 - Raspberry;

Field Of Science
1140 - Weed science;

Keywords

blueberry

red raspberry

fruit quality

polyphenols

weeds

herbicide

Goals / Objectives
The objectives of this research is to determine whether (1) herbicides used for primocane management in PNW red raspberry cultivars modify berry quality and (2) weed species growing within plantings of PNW blueberry cultivars modify berry quality. Our research hypotheses are that (1) primocane management programs will increase sugar content, decrease organic acid content, and increase anthocyanin/polyphenol content of berries compared to fruit from raspberry plants not treated with herbicides to remove the first flush of primocanes, and (2) different perennial weed species growing alongside blueberry plants will have unique effects on berry sugar, organic acid, and anthocyanin/polyphenol content.

Project Methods
Trial #1, Raspberry: Red raspberries of three commonly-grown new cultivars (probably 'Cascade Bounty', 'Chemainus', and 'Saanich'), as well as the industry standard cultivar ('Meeker'), are currently established at WSU NWREC and will be used for this trial. Plots will measure 15 feet of row for each cultivar. Treatments will include application of primocane management products (carfentrazone, oxyfluorfen, or saflufenacil) in late March or early April after the first flush of primocanes have emerged to about 10 cm in height. Carfentrazone and oxyfluorfen are currently registered products, while saflufenacil is currently in IR-4 testing with registration likely to occur at some point within the next five years. While these three herbicides have the same mode of action, they vary significantly in their ability to slow the second flush of primocanes, with saflufenacil slowing regrowth the least, followed by carfentrazone and oxyfluorfen. A hand-removal of primocanes at the same stage of growth will constitute a fourth treatment. All treatments will be compared to nontreated raspberries. The effects of these applications on primocanes and weeds will be monitored periodically from May through September, including primocane growth during the summer and total cane counts at the end of the season. Plots will be hand-harvested to determine impacts of these treatments on yield. Fifty-berry weights will be determined at the time of each harvest. The economic effect of cane burning in these raspberry plots will be estimated based upon berry yield. Additionally, 50-ml berry samples will be collected from each plot and frozen at -80 °C until fruit quality analyses are performed. Three-berry subsamples will be extracted in acidified methanol for sugar, organic acid, and anthocyanin/polyphenol identification and quantification using HPLC and/or spectrophotometry (after Nwankno et al. 2012). The experimental design will be a randomized complete block with three replicates. Means will be separated using Tukey's Honestly Significant Difference test.Trial #2, Blueberry: Blueberries of three commonly-grown cultivars (probably 'Bluecrop', 'Draper', and 'Duke') currently established in grower fields near Lynden and Mount Vernon, WA will be identified for this trial. For each cultivar, plots will be identified with existing monotypic weed populations from rows in the same part of each field. Four common perennial weed species will be tested: broadleaf dock, Canada thistle, quackgrass (Elymus repens), and creeping buttercup (Ranunculus repens). Nonweedy check plots will also be established. Plots will measure 15 feet of row, including about 5 well-established blueberry bushes of similar size. A minimum infestation level of 75% weed cover will be used to determine plot locations. Weeds of other species in designated plots will be removed by hand for the duration of the trial. Weeds will be allowed to grow in the plots until about two weeks prior to harvest or in the early flowering stage of weed growth (depending on species), at which time weeds will be clipped at the soil line and above-ground biomass will be collected, dried, and weighed. Plots will then be hand-harvested to determine impacts of these weeds on yield. Fifty-berry weights will be determined at the time of each harvest. The economic effect of weed species presence in blueberry plots will be estimated based upon berry yield. Additionally, 50-ml berry samples will be collected from each plot and frozen at -80 °C until used for fruit quality analyses. Three-berry subsamples will be extracted in acidified methanol for sugar, organic acid, and anthocyanin/polyphenol identification and quantification using HPLC and/or spectrophotometry (after Nwankno et al. 2012). The experimental design for each cultivar will be a randomized complete block with four replicates. Means will be separated using Tukey's Honestly Significant Difference test.

Progress 04/27/15 to 01/16/19

Outputs
Target Audience:Producers of red raspberry and blueberry in Washington and the rest of the Pacific Northwest (Oregon and British Columbia), horticulturists, and weed scientists. Changes/Problems:Fruit quality work was completed in early 2017, so 2017 and 2018 projects were focused on raspberry and blueberry productivity (crop growth, yield, and fruit size) and weed control from different herbicide programs. What opportunities for training and professional development has the project provided?The PI and Weed Science Professionals assigned to the program attended the Western Society of Weed Science annual meeting in Garden Grove, CA during 2018. The PI also attended and presented at the Washington Weed Conference in Wenatchee, WA. How have the results been disseminated to communities of interest?Presentations: Effects of cane burning on older raspberry fields. November 29, 2018. Washington Small Fruit Conference, Lynden, WA (approximately 200 growers and crop consultants). Herbicide programs to control problem weeds in blueberries. November 28, 2018. Washington Small Fruit Conference, Lynden, WA (approximately 150 growers and crop consultants). Herbicide testing in raspberry. November 2, 2018. Washington Red Raspberry Commission research review, WSU NWREC (approximately 25 growers and crop consultants). Herbicide testing in blueberry. November 1, 2018. Washington Blueberry Commission research review, WSU NWREC (approximately 25 growers and crop consultants). Weed management in berry crops. March 23, 2018. Skagit County Extension Grower Meeting, WSU NWREC (approximately 25 growers and crop consultants). Weed control in northwestern Washington berries and vegetable seed crops. February 8, 2018. Wilbur-Ellis Grower Meeting, La Conner, WA (approximately 75 growers and crop consultants). To cane burn or not to cane burn: that is the question. January 25, 2018. Lower Mainland Grower Short Course, Abbotsford, BC (approximately 200 growers and crop consultants). Weed management of berry crops. January 11, 2018. North Willamette Horticulture Society Annual Meeting, Canby, OR (approximately 150 growers and crop consultants). What do you plan to do during the next reporting period to accomplish the goals?Two final berry trials will be completed during winter, 2019. One is a baby raspberry herbicide trial, and the second is a yellow nutsedge control trial in blueberry. This project will be completed at the end of May, 2019.

Impacts
What was accomplished under these goals? (1) Cane burning in red raspberry. The objective of this trial was to determine how raspberry vigor may influence the effects of caneburning treatments and potentially affect stand longevity. The 2018 trial was established in 2017 at Lynden, WA at two ends of the same 'Meeker' field. Two rows at the eastern end of the field were designated as "low vigor", while two rows at the western end of the field were "high vigor". Both sections received identical caneburning treatments, and individual plots received the same treatments each year. Initial vigor estimates showed that low vigor plots contained fewer floricanes than high vigor plots (77 and 101 canes/25 ft, respectively). Floricane counts did not differ prior to application of caneburning treatments for each of the two two vigor categories. Floricane counts at the end of 2018 were lower for nearly all treatments than at the end of 2017. In the low vigor section (fewer than 100 floricanes/25 ft of row). After two years of cane burning, counts only increased with 3 of the 11 cane burning treatments: carfentrazone applied to 1- to 2-inch primocanes with no second carfentrazone application (Treatment 2), oxyfluorfen applied to 1- to 2-inch primocanes with no second carfentrazone application (Treatment 7), and no cane burning (Treatment 11). In the high vigor section (100 or more floricanes/25 ft of row), cane counts increased with 7 of the 11 cane burning treatments. Decreases in cane counts resulted from: carfentrazone applied to 4- to 6-inch primocanes with or without late carfentrazone (Treatments 3 and 5) and oxyfluorfen applied to 4- to 6-inch primocanes with or without late carfentrazone (Treatments 8 and 10). Sample yield did not differ by caneburning treatment in either vigor classification or in overall sample yield across the two vigor classes in either year. Fifty-berry weight also did not differ among the treatments in low vigor raspberries in 2017, or in high vigor raspberries in either year. Overall, the trend was for greater yield with cane burning than without. Conclusions: Taking into account both berry yield and plant vigor in 7-year-old Meeker, the following conclusions are apparent: (1) If dormant season cane counts were 100 floricanes/25 ft or greater, the greatest number of canes were produced with early cane burning programs (when primocanes were 2 inches or less), with or without late carfentrazone treatments. It also improved cane count when primocanes were not treated, or treat late only on the sides of the bed. It was better to avoid "standard" cane burning (treating 4- to 6-inch primocanes) with or without late carfentrazone. If dormant season cane counts were less than 100 floricanes/25 ft, plants responded best to no cane burning, or early carfentrazone or oxyfluorfen with no late carfentrazone treatments. (2) Blueberry Herbicide Programs. Trials were conducted near Lynden, WA ('Duke' and 'Draper'), near Burlington, WA ('Reka'), and near Eltopia, WA ('Draper', and 'Elliott') in which the same herbicide combinations (as well as rates and timings) were applied to all. This is a repeat of the trials conducted in 2017, and the same plots were treated with the same program in both years. Blueberry injury. No herbicide injury to blueberry plants was observed in any of these trials during either 2017 or 2018. Leaf growth appeared normal, with no chlorosis or stunting noted. Blueberry plants in both central and western Washington appeared to respond similarly to these herbicide programs. Weed control. In 2017, weed species composition and control percentages were quite variable across locations. 'Reka' plots at Burlington contained three tough weed species: quackgrass (Elymus repens), yellow nutsedge (Cyperus esculentus), and wild buckwheat (Fallopia convolvulus, formerly Polygonum convolvulus). Quackgrass was too patchy in the plots to gain information on control (data not shown), but the other two species were fairly common in all the plots and replicates, although control of these species did not differ among these Programs. Yellow nutsedge cover generally increased from July 14 to October 3, not surprising for this warm-season perennial weed. It did not appear that any treatment was especially active on yellow nutsedge, although it must be pointed out that the plots had been accidentally oversprayed with Chateau in the summer and Gramoxone in the fall, just prior to the application of the tested herbicides, so foliar uptake of the tested products did not occur, probably reducing their activity on that weed. Wild buckwheat control also did not differ among the treatments, although it appears that Programs 6, 7, and 8 had a suppressive effect on that weed. Since all three of those programs (and the apparently non-effective Linex + Aim from Program 5) had post-flowering treatments with Callisto + Gramoxone, we presume that suppression from these three programs were primarily due to late dormancy applications of Sinbar, Casoron, and Zeus Prime. In 2018, yellow nutsedge began at about the same percent cover noted in 2017, and again increased in most programs through October. Numerically, Programs 4, 5, and 8 showed reduced yellow nutsedge cover in October compared to the July evaluation, but these reductions were limited in scale and likely were not related to herbicide applications. Wild buckwheat in October was generally much lower in 2018 than in 2017. There was a significant difference between wild buckwheat cover in Program 6 (2%) and Program 5 (30%), although other programs resulted in similar control as Program 6 and 5. At Lynden, both 'Duke' and 'Draper' plots began and remained remarkably clear of weeds, with all providing essentially full season-long weed control in both 2017 and 2018. Similarly, at Eltopia tested programs showed good early season weed control in both 'Duke' and 'Draper', with June control ranging from 89 to 98% control. Plots at Eltopia were handweeded following the June evaluation, so weed control in both cultivars remained excellent through early October. In 2018, weed control in all programs were statistically similar for each evaluation. Control ranged from 89 to 98% in April, but was considerably reduced by June (75 to 89%). Blueberry yield and fruit size. In 2017, neither 'Reka' at Burlington nor 'Duke' at Lynden differed in yield or fruit size with any of these herbicide programs. Total yield was slightly less for for 'Reka' (1135 to 1437 g/0.5 m) than for 'Duke' (1008 to 1284 g/0.5 m), with fruit size slightly smaller for 'Reka' (1.5 to 1.8 g/berry) than for 'Duke' (1.8 to 2.0 g/berry). In 2018, 'Draper' at Lynden did not differ in yield or fruit size with any of these herbicide programs. Average fruit size also did not differ among the programs. Conclusions: None of these programs, or the herbicides within each program, were injurious to established blueberry regardless of location/cultivar in either year of the trial. Given its new registration and potential for long soil residual, it is encouraging that two years of treatment including Alion did not appear to be harmful to blueberry in any trial. General weed control was good to excellent for all programs, while yield and fruit size were similar for all programs. Unfortunately, these programs did not appear to greatly affect yellow nutsedge nor wild buckwheat populations. This may have been because of the variability in those populations among the 'Reka' plots in Burlington.

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Duan, Y., T.W. Walters, and T.W. Miller. 2017. Caneburning effects on weeds, primocane growth, and fruit yield in Pacific Northwest red raspberry. HortScience 52:692-699.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Miller, T.W. and L.W. DeVetter. 2017. Effectiveness of living and compostable mulches for weed control in Pacific Northwest highbush blueberry. Acta Hortic. 1180:461-466.
• Type: Conference Papers and Presentations Status: Published Year Published: 2018 Citation: Purba, W.O., S.S. Seefeldt, and T.W. Miller. 2018. Effect of herbicides on newly transplanted red raspberry plugs. Western Society of Weed Science, Garden Grove, CA.
• Type: Journal Articles Status: Other Year Published: 2019 Citation: Miller, T.W., L.W. DeVetter, and J.R. Davenport. Under Preparation; anticipated submission in early 2018. Cane burning herbicides do not greatly affect red raspberry fruit quality, cane growth, or cane carbohydrate content. HortScience.

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Berry growers, consultants, industry personnel, and University researchers and Extension faculty. Changes/Problems:2017 trials in raspberry and blueberry proceeded as planned. Weather was a challenge in northwestern Washington, however, as only scant rain fell from June through August. This primarily impacted the baby raspberry trial, which did not receive supplemental irrigation. What opportunities for training and professional development has the project provided?Lab work at Pullman and Prosser has focused on protocol development for red raspberry cane and fruit carbohydrate analyses, so both lab technicians and PIs gained insight into the best procedures to employ when gathering this information. In addition, red raspberry and blueberry production practices in central Washington (a new area for both crops, as contrasted with extensive experience in producing these crops in western Washington) were refined. How have the results been disseminated to communities of interest?Results from these trials have been presented at the following meetings: the Washington Small Fruit Conference, Lynden, WA (2015-17), the Washington State Weed Conference, Wenatchee, WA (2016), the North Willamette Horticultural Society annual meeting, Canby, OR (2016-18), the Washington Blueberry and Red Raspberry Commission research review, Mount Vernon, WA (2015-17), the OSU Blueberry School (2015), and the Lower Mainland Horticultural Growers' Short Course, Abbotsford, BC (2015, 2017-18). A presentation was also given at the Cornell Cooperative Extension Empire State Producers Expo, Syracuse, NY (2016). Additional talks on various aspects of berry production have also been given at professional meetings (Western Society of Weed Science, Weed Science Society of America, International Weed Science Congress, American Society for Horticultural Science, International Rubus and Ribes Symposium, and International Vaccinium Symposium). What do you plan to do during the next reporting period to accomplish the goals?Additional funding for weed control research in blueberry and raspberry during 2018 has been solicited from the same funding sources who have previously funded these research projects. The second year of the trial investigating caneburning effects on raspberry vigor will be conducted in 2018, as will the herbicide testing in established blueberry. Additional herbicide testing in red raspberry will be funded by Western Regional IR-4 during 2018.

Impacts
What was accomplished under these goals? Since 2014, grant funds have been solicited and projects funded by the Washington Red Raspberry Commission, the Washington Blueberry Commission, the Washington State Commission for Pesticide Registration, the WSU Center for Sustaining Agriculture and Natural Resources, and the Western Region IR-4 Program. Projects have involved usefulness of living and biodegradable mulches for weed control in blueberry, herbicide testing in young and established red raspberry and blueberry, and effects of caneburning herbicides on fruitfulness, carbohydrate partitioning, and vigor in red raspberry. Selected results are presented below: Caneburning effects on red raspberry fruit quality and cane carbohydrates. The trial was conducted at two sites: one at WSU Northwestern Washington Research and Extension Center (NWREC) in Mount Vernon, Washington (northwestern WA) and the second at WSU Irrigated Agriculture Research and Extension Center (IAREC) in Prosser, Washington (central WA). The northwestern WA trial was conducted on five- or six-year-old 'Cascade Bounty', 'Chemainus', 'Meeker', and 'Saanich' red raspberry. Herbicides tested were carfentrazone, oxyfluorfen, and saflufenacil applied in early April. The central WA trial was conducted on third-year 'Chemainus', 'Meeker', and 'Wakefield' red raspberry. Herbicides tested were carfentrazone applied once or twice and saflufenacil applied once. Anthocyanin content was generally greater in northwestern WA, although °Brix. pH, and polyphenol content were higher in central WA. 'Meeker' had overall greater carbohydrate content than 'Chemainus'. 'Meeker' laterals had greater carbohydrate content than primocanes in northwestern WA in both years, but primocane carbohydrate content in 2015 was greater than laterals in 'Meeker' grown in central WA. Cultivar and location significantly affected aspects of red raspberry fruit quality, cane growth, and carbohydrate content, while caneburning programs did not. Primocane Management Program Trial. The objective of this trial is to determine how raspberry vigor may influence the effects of caneburning treatments and potentially affect stand longevity. The trial was established at Lynden, Washington at two ends of the same 'Meeker' field. Initial vigor estimates showed that eastern "low vigor" plots contained fewer floricanes than western "high vigor" plots (77 and 101 canes/25 ft, respectively). Floricane count did not differ going prior to application of caneburning treatments, indicating that vigor was similar among the raspberry plants in all the plots. Berry sample weight was greater in "high vigor" plots than in "low vigor" plots (327 and 290 g/m, respectively), as was 50-berry weights (1.9 and 1.8 g/berry, respectively). Neither total sample weight nor 50-berry weights differed by treatment in either section of when analyzed regardless of vigor classification. This experiment will continue into 2018. Next season's floricanes will be counted and length determined during winter 2017-18 to determine the effect of 2017 caneburning programs on raspberry growth. The plots will receive the same caneburning program in 2018, with similar berry sampling and cane counts occurring next season. Testing Herbicides in Baby Raspberry. Tissue-culture 'Cascade Harvest', 'Meeker', 'Squamish', and 'Wakefield' red raspberry plugs were transplanted by hand at WSU NWREC. Three plants of each cultivar were planted sequentially into a single row in each plot. In 2016, all herbicides were applied post-transplant over the top of each row; in 2017, pre-transplant (PRETR) herbicides were applied May 23 and post-transplant (POSTR) herbicides were applied May 26. All plots were hand-weeded after mid-season weed control was rated. The best mid-season weed control in 2016 ranged from 78 to 98%, while weed control with napropamide (40%), pendimethalin (60%), and isoxaben (75%) was less effective. By September, only Fierce was still providing an acceptable level of weed control (87%), although control ratings were quite variable among the plots. In 2017, weed control was quite variable at both evaluations and did not differ by treatment. Most products not providing acceptable weed control at mid-season (0 to 83%, control), and October weed control was 33 to 92%. Average raspberry plug response to certain herbicides was rapid in 2016. In particular, crop injury was excessive due to POSTR treatments with flumioxazin or flumioxazin + pyroxasulfone. Applying these products PRETR resulted in much greater safety in 2017. Cane length in 2016 was reduced by POSTR flumioxazin at both rates, flumioxazin + pyroxasulfone, and rimsulfuron in both July and September. In 2017, herbicide treatment did not influence raspberry growth by mid-season. By October, however, raspberry growth was maximized by flumioxazin, indaziflam, oryzalin, isoxaben, and halosulfuron. Cultivars differed significantly in their response to herbicide treatments, but not to specific treatments. This may indicate that cultivars were more sensitive to the herbicides, or were differentially injured by transplanting operations from greenhouse flats to the field. In 2016, cane growth was greatest with 'Meeker' at both evaluations. In 2017, 'Wakefield' had the longest canes in July, although cultivars did not differ in their growth by October. Testing Herbicides in Established Blueberry. Five blueberry trials (consisting of four different cultivars in three locations) were conducted during 2017. The objective was to test several herbicide programs in established blueberry to determine the potential for crop injury and aid in weed control in western and central Washington. Dormant-season applications were in March, post-flowering applications were made in June, and early fall applications were made in September. No herbicide injury to blueberry plants was observed in any of these trials. As may be expected, weed species composition and control percentages were quite variable across locations. 'Reka' plots at Burlington contained three tough weed species: quackgrass, yellow nutsedge, and wild buckwheat. Quackgrass was too patchy in the plots to gain information on control, but the other two species were fairly common in all the plots and replicates, although control of these species did not differ among these products. Wild buckwheat control also did not differ among the treatments, although it appears that three programs had a suppressive effect on that weed (late dormancy applications of terbacil, dichlobenil, and sulfentrazone + carfentrazone). Neither 'Reka' at Burlington nor 'Duke' at Lynden differed in yield or fruit size after treatment with any of these herbicide programs. Total yield was slightly less for for 'Reka' (2270 to 2874 g/m) than for 'Duke' (2016 to 2568 g/m), with fruit size slightly smaller for 'Reka' (1.5 to 1.8 g/berry) than for 'Duke' (1.8 to 2.0 g/berry).

Publications

• Type: Journal Articles Status: Awaiting Publication Year Published: 2017 Citation: Duan, Y., T.W. Walters, and T.W. Miller. In press. Caneburning effects on weeds, primocane growth, and fruit yield in Pacific Northwest red raspberry. HortScience.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2017 Citation: Miller, T.W. and L.W. DeVetter. In press. Effectiveness of living and compostable mulches for weed control in Pacific Northwest highbush blueberry. Acta Hortic.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Miller, T.W., D.A.M. Jarret, R.M. Brennan, and R.D. Hancock. 2016. Does primocane management affect raspberry fruit yield or anthocyanin content? Acta Hortic. 1133:363-369
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Miller, T.W. 2016. Effect of autumn simazine with late-dormancy herbicide applications in matted-row strawberry. Keynote Speaker, Weed Management in Crops and Non-agricultural Land: Weed Control in Plantation Crops, C. Maneechote, moderator. International Weed Science Congress, Prague, Czech Republic.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Miller, T.W. and C.R. Libbey. 2016. Testing herbicides for young blueberry plantings in the Pacific Northwest. Weed Science Society of America, San Juan, PR. WSSA Abstracts, CD.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Growers, consultants, industry personnel, University personnel Changes/Problems:Red raspberry work proceeded as planned, although initial yield in central Washington (2015) was not as great as was expected. Yield was much better in 2016, due to implementation of improved production practices. Initial processing of raspberry cane samples for carbohydrate analysis was also delayed, but the use of a spice grinder resulted in sufficiently small particle sizes to assure good carbohydrate extraction. Adaption of the berry processing protocol from the grape protocol was smooth and on schedule. In blueberry, the initial idea was to determine the effect of perennial weed competition on berry quality. This focus was replaced by instead testing two living mulch plant species in the understory of newly-planted and established blueberry to determine their effect on plant growth, weed control, and berry quality. Herbicide testing in first- or second-year blueberry and raspberry plantings have also been added, in effort to generate new labels for herbicides in these crops, as well as providing data to allow use earlier in the life of the planting. What opportunities for training and professional development has the project provided?Lab work at Pullman and Prosser has focused on prototcol development for red raspberry cane and berry carbohydrate analyses, so those both lab technicians and PIs gained insight into the the best way to gather this information. In addition, because red raspberry production in central Washington is not widespread, production practice in Prosser has been refined from western Washington production practices to an acceptable level. How have the results been disseminated to communities of interest?Results from these trials have been presented at the following meetings: the Washington Small Fruit Conference, Lynden, WA (2015, 2016), the Washington State Weed Conference, Wenatchee, WA (2016), the Washington Blueberry and Red Raspberry Commission research reviews, WSU NWREC (2015, 2016), the North Willamette Horticultural Society annual meeting, Canby, OR (2015-2016), the OSU Blueberry School, Corvallis, OR (2015), the Lower Mainland Horticultural Growers' Short Course, Abbotsford, BC (2015), a webinar presented at the Cornell Cooperative Extension Empire State Producers Expo, Syracuse, NY (2016). Additional talks on various aspects of berry production have also been given at professional meetings (Western Society of Weed Science, Weed Science Society of America, International Weed Science Congress, American Society for Horticultural Science, International Rubus and Ribes Symposium, and International Vaccinium Symposium). What do you plan to do during the next reporting period to accomplish the goals?Additional funding for weed control work in blueberry and red raspberry during 2017 has been sought from the same funding agencies who previously funded this research, with the exception of the Western Region IR-4 program. The caneburning/red raspberry carbohydrate work is now complete and we are awaiting lab reports at this time. Herbicide testing in young blueberry work is complete, and one more year of herbicide testing in young raspberry will be conducted in 2017. The biodegradable and living mulch project in young blueberry is complete, but one more year of testing of living mulches in established blueberry will be conducted. New projects involving when and when not to caneburn red raspberry planting and differential herbicide performance in central and western Washington blueberry will begin in 2017.

Impacts
What was accomplished under these goals? Grant funds have been solicited and projects funded by the Washington Red Raspberry Commission, the Washington Blueberry Commission, the Washington State Commission for Pesticide Registration, the WSU Center for Sustaining Agriculture and Natural Resources, and the Western Region IR-4 Program since 2014. Projects involve usefulness of living and biodegradable mulches for weed control in blueberry, herbicide testing in young blueberry and red raspberry, and effects of caneburning herbicides on fruitfulness and carbohydrate partitioning in red raspberry. Plots have been sited in Lynden, Mount Vernon, Eltopia, and Prosser. Selected results are presented below: Red Raspberry Caneburning Trials: Combined data from the two trials. The two datasets (the Northwestern Washington Research and Extension Center, Mount Vernon and the Irrigated Agriculture Research and Extension Center, Prosser) had a few points of intersection. Both included the raspberry cultivars 'Chemainus' and 'Meeker', and both had applications of the cane burning herbicides Aim and Treevix. When these selected data were pooled for the two sites, cane biomass was significantly affected by the trial location. Raspberry floricane and fruiting lateral biomass was less at IAREC than at NWREC, while primocane biomass was greater at IAREC. There were no clear trends between 'Chemainus' and 'Meeker' primocane biomass, but 'Chemainus' floricanes tended to be heavier than 'Meeker' floricanes. While treatment with Treevix generally resulted in lower biomass of all cane types, this difference was not statistically significant. It will be interesting to see if fruit quality or cane carbohydrate content differs by herbicide treatment, cultivar, or trial location. These data should become available later this winter. Blueberry Herbicide Trials: Blueberry injury. When averaged across all herbicide treatments and timings, crop injury was significantly greater in 'Elliott' than in the other cultivars tested in 2016. Injury with 'Bluecrop', 'Draper', and 'Duke' were less than 10% for all evaluations, compared to 10% injury in 'Elliott' in the late May evaluation. 'Elliott' plants had recovered considerably by August (average of 6% injury). Although this rating was statistically greater than for the other cultivars, injury levels less than 10% are generally considered below the threshold of concern. Individual treatments did not differ by cultivar, although it is interesting to look at the data sorted in that manner. In 'Elliott', 12 treatments exceeded 10% injury in May, contrasted with 6 treatments in 'Bluecrop' and 'Draper', and 5 treatments in 'Duke'. By August, these totals were 6 treatments in 'Elliott' and 1 each in 'Draper' and 'Bluecrop', while 'Duke' had completely recovered from any early injury. The treatments tending to cause the greatest injury to blueberry foliage across the cultivars were Treevix, Sandea, Linex, and Matrix applied to leafed-out blueberry (33, 26, 18 and 15% injury in late May, respectively, data not shown). By August, however, no treatment was causing greater than 7% injury, and those same four treatments listed above were causing only 4, 6, 6, 2% injury, respectively. Stated in a different way, the greatest injury with any dormant-season application was only 6% in May, and only 4% by August, indicating that dormant-season applications with all these products at these rates were very safe to blueberry plantings at least one year old. Weed control. As may be expected, weed species composition and control percentages were quite variable across locations, and most treatments did not result in statistically different early-season weed control. There were, however, some trends in the weed control data. First, directed spray applications were typically more effective than were over-the-top applications, regardless of timing of application. Treatments tending to provide higher levels of weed control in late May were directed sprays with Alion, Linex, or Matrix (83 to 95% control). As in the 2015 trial, these results are not considered to relate so much to blueberry cultivar or the age of the blueberry bushes as to the propensity of most annual weeds to emerge during the first year of a perennial planting. Good weed control during the first year reduces the amount of weed seed dropping to the soil surface that will germinate the next year, while no cultivation in the crop row leaves buried weed seeds buried. These factors combine to result in far fewer weeds in later years of the planting than in the first. Conclusions: There are a few trends apparent in these data: 1. These products were safe applied to dormant blueberry (2% injury or less by early May), regardless of location/cultivar or whether applied over-the-top or as a directed spray to the base of the plants. 2. Over-the-top treatments with Treevix, Sandea, Linex, or Matrix applied post-budbreak caused slight to severe blueberry injury at all locations by late May. By August, however, injury for all these applications was rated at 6% or less. 3. The not-yet-registered product Alion looks very safe applied directed-spray or over-the-top of dormant blueberry (1 to 2% injury), or when applied directed-spray post-budbreak (4% injury), but caused about 12% injury when applied over-the-top post-budbreak. Callisto and Stinger also were quite safe in all application timings. 4. Weed control was generally best with Alion, Linex, or Matrix applied as a directed spray. Blueberry Living/Biodegradable Mulch Trials: When managed properly, living mulches can effectively suppress annual weed growth while not negatively affecting crop productivity. Compostable and/or biodegradable mulches (BDM) also show promise for weed control in many crops and are currently being investigated for usefulness in berry production systems. In a newly-planted blueberry trial, 'Draper' plants were transplanted from 1-gal pots into the field in March 2015. Greenhouse-grown living mulch plants, creeping buttercup (Ranunculus arvensis) and sweet woodruff (Galium odoratum), were transplanted to a density of 1 plant/ft2 at the same time as blueberry. Other plots were treated with 5 cm of sawdust or by an experimental BDM made of black spunbond polylactic acid. These treatments were applied to cover all bare soil. Soil in the fifth treatment was left bare. BDM provided good to excellent weed control, reducing weeding time by 64% over the two years in the trial as compared to bare ground plots, including a 90% reduction in 2015. Sawdust and creeping buttercup also reduced weeding time by 57 and 41%, respectively, performing better than sweet woodruff (increased weeding time by 15%). Meadow vole (Microtis spp.) damage was extensive in all plots by the end of the second year, although blueberry plant mortality was less in sawdust than in other treatments. Blueberry root and shoot growth was best in BDM and sawdust plots indicating that these living mulches were not a good option in newly-planted blueberry. In a separate trial in a well-established 'Duke' field, creeping buttercup and sweet woodruff were transplanted as described above in March 2015 and their effects on weeds and blueberry were compared to those from sawdust mulch. Living mulches did not affect hand-weeding time in 2015, or mean berry weight and berry yield in either 2015 or 2016. The established trial will be maintained through 2017 to determine effects of fully-established creeping buttercup or sweet woodruff on blueberry growth or yield.

Publications

• Type: Journal Articles Status: Submitted Year Published: 2016 Citation: Duan, Y., T.W. Walters, and T.W. Miller*. 201x, submitted. Caneburning effects on weeds, primocane growth, and fruit yield in Pacific Northwest red raspberry. HortScience
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Miller, T.W., D.A.M. Jarret, R.M. Brennan, and R.D. Hancock. 2016. Does primocane management affect raspberry fruit yield or anthocyanin content? Acta Hortic. 1133:363-369.
• Type: Journal Articles Status: Submitted Year Published: 2016 Citation: Duan, Y., T.W. Walters, and T.W. Miller. 201x, submitted. Caneburning effects on weeds, primocane growth, and fruit yield in Pacific Northwest red raspberry. HortScience
• Type: Journal Articles Status: Accepted Year Published: 2016 Citation: Miller, T.W. and L.W. DeVetter. 201x, accepted. Effectiveness of living and compostable mulches for weed control in Pacific Northwest highbush blueberry. Acta Hortic.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Miller, T.W. and C.R. Libbey. 2016. Testing herbicides for young blueberry plantings in the Pacific Northwest. Weed Science Society of America, San Juan, PR. WSSA Abstracts, CD

Progress 04/27/15 to 09/30/15

Outputs
Target Audience:Producers of red raspberry, blueberry, and strawberry in Washington and the rest of the Pacific Northwest (Oregon and British Columbia), agricultural consultants, farmworkers, fruit industry personnel, fruit and horticultural scientists, weed scientists. Changes/Problems:These projects are progressing generally as anticipated. Lab analysis of raspberry fruit and cane materials is taking longer than anticipated, however, although data will be available in the coming months. What opportunities for training and professional development has the project provided?An abstract of the blueberry trial data was submitted for a poster presentation at the XI International Vaccinium Symposium to be held in Orlando, Florida on April 10-14, 2016. Additional publications (journal articles and presentations at scientific meetings) will result from this research in raspberry and blueberry trials. All results will be presented to berry growers as they become available over the coming months and years. How have the results been disseminated to communities of interest?Presentations of these data were provided to berry producers at the Washington Small Fruit Conference in Lynden, WA (December 2-3, 2015). An additional presentation will be provided to Oregon growers and berry industry people in January, 2016. What do you plan to do during the next reporting period to accomplish the goals?Trials will be conducted in 2016 using the same plots and treatments as in 2015. Data from these second-year raspberry plots will provide good evidence of herbicide effects on raspberry fruit quality or carbohydrate content of raspberry cane tissues. The first-year blueberry trial will be extended into 2016 to evaluate mulch effectiveness in the second year of establishment. Weed control, living mulch, and blueberry growth parameters will be measured as before. We will also be able to collect our first harvest data from the newly-planted blueberry plots in 2016. Vole presence and usage of plots will also be estimated during winter (2015-16), as will emergence of mummy berry (Monilinia vaccinii-corymbosi) apothecia beneath the bushes or evidence of infection on blueberry shoots or flower buds in spring 2016. Living mulch comparisons in established blueberry will provide a second year of yield information as well as the effect of these living mulches on weed control under the bushes.

Impacts
What was accomplished under these goals? RASPBERRY: Two trials were conducted at two sites during 2014-15: one at WSU Northwestern Washington Research and Extension Center (NWREC) in Mount Vernon and the second at WSU Irrigated Agriculture Research and Extension Center (IAREC) in Prosser. NWREC Trial. The trial was conducted on four-year-old 'Cascade Bounty', 'Chemainus', 'Meeker', and 'Saanich' red raspberry. Berry size was not affected by herbicide treatment or by canopy location. Fruit size ranged from 3.7 to 4.0 g/berry when analyzed across cultivars. There was a trend toward larger fruit following applications of Aim or Goal when compared to nontreated raspberry or raspberry treated with Treevix. Fruit size did, however, differ among the four cultivars tested, whether sampled on the east or west side of the canopy. 'Saanich' and 'Chemainus' berries were up to 15% larger than 'Meeker' berries; 'Saanich' fruit was also larger than 'Cascade Bounty' fruit. Cane dry weight did not significantly differ from among the herbicide treatments. Primocane biomass tended to be greater after treatment with Treevix compared to nontreated raspberry, while treatment with Goal and Aim generally resulted in less primocane biomass. This relationship was reversed in floricane biomass, while treatment with Goal or Treevix tended to reduce biomass of fruiting laterals. Because these differences were not statistically significant, however, no definitive conclusions should be taken from these data. Cane biomass also did not differ by cultivar. In general, 'Cascade Bounty' produced comparatively more primocane and fruiting lateral biomass than the other cultivars, and generally less floricane biomass. But again, these distinctions are mainly speculative. IAREC Trial. The trial was conducted on second-year 'Chemainus', 'Meeker', and 'Wakefield' red raspberry. Cane dry weight did not significantly differ from among the herbicide treatments. Primocane biomass tended to be less in herbicide-treated raspberry than in nontreated raspberry. Treatment with Treevix generally resulted in more floricane biomass and less fruiting lateral biomass than what was sampled after treatment with other herbicides or in nontreated raspberry. There was generally response of these raspberries following one or two treatments with Aim. But because these differences were not statistically significant, no definitive conclusions should be taken from these data. While cane biomass did differ among the tested cultivars, there were few trends in the data. 'Chemainus' and 'Wakefield' produced more primocane biomass than 'Meeker', while 'Meeker' produced more floricane biomass than 'Wakefield'. 'Wakefield' produced more fruiting lateral biomass than either 'Chemainus' or 'Meeker'. Combined data from the two trials. The two datasets had a few points of intersection. Both included the raspberry cultivars 'Chemainus' and 'Meeker', and both had applications of the cane burning herbicides Aim and Treevix. When these selected data were pooled for the two sites, cane biomass was only significantly affected by the trial location. Raspberry cane biomass at IAREC was less than at NWREC for all cane types. Floricanes at IAREC were only half the biomass as at NWREC, and fruiting laterals produced 60% less biomass at IAREC. There were no clear trends between 'Chemainus' and 'Meeker' cane biomass, and while treatment with Treevix generally resulted in less biomass of fruiting laterals, this difference was not statistically significant. It will be interesting to see if fruit quality or cane carbohydrate content differs by herbicide treatment, cultivar, or trial location. BLUEBERRY: The trials were conducted at two locations. The first was on newly-planted blueberry at WSU Mount Vernon NWREC and the second in established blueberry near Burlington, WA (Sakuma Brothers Farms, cooperator). Newly-planted Trial. Weeding time in May was quite high for living mulch plots, averaging slightly more than 9 or 10 minutes per meter per person for creeping buttercup (Ranunculus arvensis) and sweet woodruff (Galium odoratum), respectively. There was no statistically significant difference in weeding time between bare ground/herbicide-treated plots, sawdust plots, and BDM plots, although the BDM was practically weed free at the May weeding. In July, weeding time was similar for plots treated with living mulches, sawdust, or BDM, ranging from 0.7 to 1.7 minutes per meter per person. Bare ground/herbicide plots took significantly longer to weed, although weeding time was the same as recorded in May. Total weeding time (May July hand-weeding times) was greatest for plots containing the two living mulches or in bare ground/herbicide plots. Sawdust and BDMs provided the best weed control, requiring 2.9 and 0.8 minutes of hand-weeding time per meter per person, respectively. Despite the growth of living mulch plants among the blueberry plants, there was not a significant difference in blueberry shoot growth due to these treatments. Average shoot growth ranged from 18 to 23 cm across the treatments, indicating that there was little competition occurring between blueberry and living mulch plants, at least during this first year of growth. Had plots not been irrigated and fertilized per industry standard, this result may have been different. So, too, if living mulch plants had been fully established for the full season, they may have significantly reduced blueberry shoot growth. A second year of testing, including berry yield on these one-year old plants, will provide good evidence of whether living mulches provide excessive competition to young blueberry. Tunneling by meadow voles was apparent in all treatments, although visible damage to blueberry plants was only noted in two plots (one plant each in sawdust and sweet woodruff; both of these plots were on the north end of the row, adjacent to a grass-covered field road). Vole activity had also enticed dogs or coyotes to tear the BDM in those plots. Winter use of plots by voles will continue to be evaluated over the next three months, and blueberry damage will be assessed as plants break dormancy. Other than where ripped by animals, the BDM performed well in this trial. Weeding time was minimized in these plots, while the material remained intact throughout the summer. Established Trial. Weeding time was not significantly affected by presence or absence of living mulch plants growing under established blueberry bushes. There was a trend in the data that plots planted to living mulches were more difficult to weed, however, requiring 3.8 to 5 minutes per meter per person. Most of the time required for hand-weeding was due to difficulty workers experienced in accessing the beds underneath the bushes. Blueberry plants generally were a meter or more tall and living mulch plants and sawdust were quite shaded underneath, which likely reduced weed seed germination and weed growth. Berry yield did not differ among treatments, ranging from 744 to 935 grams of fruit per bush. This was not an unexpected result, as our previous research has shown that blueberry and other perennial plants often do not respond to weed control strategies employed during a single growing season. Harvested fruit size ranged from 1.8 to 1.9 grams per berry regardless of living mulch treatment. Living mulch growth during 2015 also did not significantly affect average blueberry shoot growth. Current-season blueberry growth ranged from 28 to 36 cm per shoot, with no apparent reductions due to living mulch competition. Presence of a fully-established living mulch under these blueberry plants during a second growing season may alter this result in 2016, however.

Publications

• Type: Journal Articles Status: Accepted Year Published: 2015 Citation: Miller, T.W., D.A.M. Jarret, R.M. Brennan, and R.D. Hancock. 201x, accepted. Does primocane management affect raspberry fruit yield or anthocyanin content? Acta Hort.
• Type: Books Status: Awaiting Publication Year Published: 2015 Citation: Hanson, B. and T.W. Miller. 2015. Use of 2,4-D in orchard, vineyard, and small fruit production in the United States. In: Biologic and economic assessment of benefits from use of phenoxy herbicides in the United States. S. McDonald, ed. National Agricultural Pesticide Impact Assessment Program Special Report, USDA.
• Type: Books Status: Awaiting Publication Year Published: 2015 Citation: Miller, T.W. 2015, in press. Herbicide injury. In: Compendium of Raspberry and Blackberry Diseases and Insects. R.R. Martin, ed. American Phytopathological Society
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2015 Citation: Libbey, C.R. and T.W. Miller. 2015 (in press). Dormant season weed control in established strawberry. Proceedings, Western Society of Weed Science, Portland, OR.