Progress 12/26/07 to 12/25/12
Outputs
Progress Report Objectives (from AD-416): Test emerging methyl bromide alternative chemicals for their efficacy in controlling various soilborne plant pathogens in cut flowers and other ornamental crops. Test methyl bromide alternative chemicals, rates, and application methods to meet California certification standards for nematode-free production of tree, vine, and rose nurseries. Develop various application methods, soil amendments, and physical barriers to reduce the emissions and enhance efficacy of the chemical alternatives to methyl bromide. Develop integrated weed control strategies using combinations of methyl bromide alternative fumigants with herbicides and non-chemical management techniques to improve weed control. Approach (from AD-416): Research techniques will include extraction of soil fungal pathogens and nematodes, isolation and identification, population assessment and identification of native weeds, in-situ measurements of fumigant emissions and fumigant gas dispersion in soils, and determining impacts of various combinations of fumigant formulation and surface containment on efficacy and emission reductions. Experimental platforms will range from laboratory microcosms, soil columns, greenhouse pots, to small field plots and demonstration-scale field trials. Stakeholder participation in planning and implementation of research trials will be crucial. Outcomes from these research activities will be transferred to the stakeholders. This is the final report for the project 5302-13220-004-00D, which was terminated on December 25, 2012 and merged with project 5302-13000-011- 00D. Details of progress on milestones relating to methyl bromide alternatives research can be found in the 2013 Annual Report for 5302- 13000-011-00D. Substantial results were obtained over the 5 years of the project. Dose response of low toxicity chemicals including acrolein and dimethyl disulfide as replacements for pre-plant methyl bromide fumigation was developed in cut flower production to control weeds and pathogens. Use of these soft chemicals has potential impact on weed and disease control in areas where township caps and buffer zone requirements preclude the use of the other alternatives such as 1,3-D. Etiology of calla lily root pathogenic isolates was molecularly characterized by PCR amplification and restriction enzyme digestion, which provided understanding of genetic composition of soil pathogens in ornamental crops. Biofumigation with soil-incorporated plant materials demonstrated measurable production of volatile methyl sulfide and dimethyl disulfide gases and the beneficial impact on controlling soilborne pathogens. Chemical combinations of 1,3-D plus chloropicrin, iodomethane plus chloropicrin, and propargyl bromide generally controlled root-knot and citrus nematodes similar to methyl bromide in grape replant soil fumigation treatment. Replanting of perennial orchards and tree and vine nurseries in California depends on soil fumigation for production and delivery of nursery crops free of economically important plant parasitic nematodes. A series of field trials showed that effective nematode control was achievable with half rates of 1,3-D when the field was covered with low impermeable plastic films. Use of these low permeability films also drastically reduced both peak flux and cumulative fumigant gas emissions, which is beneficial to protect worker exposure risk and regional air quality. In addition to films, field studies also tested and showed that fumigant emissions were significantly reduced using water seal or chemical and organic amendments. Field trials also demonstrated that spot fumigation achieved a 10-fold reduction in atmospheric volatile organic compounds load in orchard replant soil fumigation. Field trials on herbicide efficacy and crop safety contributed to the overall effort on methyl bromide alternatives for weed control in field perennial woody nurseries. The overall impact of the accomplishments is that ornamental and cut flower, perennial nursery, grape, and orchard growers have new information on which to make decisions concerning soil fumigation with methyl bromide alternatives to maximize profits while sustaining yield. Accomplishments 01 Extraction and amplification of pathogen DNA from soil. Soil pathogen assays are usually carried out in the laboratory using traditional plating techniques for commonly found species such as Verticillium dahliae, Fusarium oxysporum, Pythium spp. and Phytophthora cactorum. This kind of analysis tends to be site specific, therefore, a study was initiated on extraction and amplification of pathogen DNAs. Soil samples were collected in fumigated strawberry fields and flower fields. DNA of the calla lily pathogen was extracted from soil samples collected from diseased fields and has been successfully amplified using PCR. The methodology developed for successful extraction and amplification of pathogenic DNAs from soil can lead to a quantitative assay for the pathogens and enable much improved management of soilborne diseases in ornamental and strawberry production in California or anywhere in the world. 02 Fumigant behavior in soil and nematode control. The efficacy of nematode control in soils with deep rooted tree crops requires fumigant movement to deeper depths. Limited research is available for this effect, therefore, a field trial was conducted to evaluate fumigant behavior and nematode control in an almond orchard near Merced, California. Fumigation treatments included three surface sealing methods (bare soil, standard polyethylene film or PE film, and a totally impermeable film or TIF film) and four application rates of Telone C35. The TIF film significantly reduced fumigant emission peak flux compared to the standard PE film. All full rate treatments achieved 100% kill of the residential nematodes in the top 3 foot soil, but we found survival nematodes in the 3 to 5 foot soil depth. The findings provide valuable information to growers, the soil fumigation industry, and regulatory agencies regarding the use of TIF film with respect to fumigant movement in soil and nematode control, and further highlight existing difficulties in controlling nematodes at deep soil depths.
Impacts
(N/A)
Publications
- Gao, S., Ajwa, H., Qin, R., Stanghellini, M., Sullivan, D. 2013. Emission and transport of 1,3-dichloropropene and chloropicrin in a large field tarped with VaporSafeTM TIF. Environmental Science and Technology. 47:406- 411.
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): Test emerging methyl bromide alternative chemicals for their efficacy in controlling various soilborne plant pathogens in cut flowers and other ornamental crops. Test methyl bromide alternative chemicals, rates, and application methods to meet California certification standards for nematode-free production of tree, vine, and rose nurseries. Develop various application methods, soil amendments, and physical barriers to reduce the emissions and enhance efficacy of the chemical alternatives to methyl bromide. Develop integrated weed control strategies using combinations of methyl bromide alternative fumigants with herbicides and non-chemical management techniques to improve weed control. Approach (from AD-416): Research techniques will include extraction of soil fungal pathogens and nematodes, isolation and identification, population assessment and identification of native weeds, in-situ measurements of fumigant emissions and fumigant gas dispersion in soils, and determining impacts of various combinations of fumigant formulation and surface containment on efficacy and emission reductions. Experimental platforms will range from laboratory microcosms, soil columns, greenhouse pots, to small field plots and demonstration-scale field trials. Stakeholder participation in planning and implementation of research trials will be crucial. Outcomes from these research activities will be transferred to the stakeholders. Pathogen control evaluations were made on cooperating methyl bromide alternatives field trials. Ornamental crop field trial on methyl bromide alternatives using chloropicrin and 1, 3-dichloropropene and non- permeable tarps is ongoing in Moss Landing, CA. This experiment will conclude in December 2012. Soil pathogen assays for the fall Parlier fumigation experiment have been completed. Assays were conducted for Verticillium dahliae, Fusarium oxysporum, Pythium spp. and Phytophthora cactorum. A study was initiated on fumigation effect on microbial community structure using phospholipid fatty acid analysis. A study of the etiology of the root rot disease of calla lily in the Moss Landing area was completed. Pythium spp. isolates were collected from diseased calla lily roots from production fields. The isolates were tested for pathogenicity in a greenhouse assay and confirmed to be the causative agent. Pathogenic isolates were evaluated using PCR and restriction enzyme digestion profiles were used to determine identity. Alternatives for soil fumigation with methyl bromide for grape replant were evaluated as a continuing project of the Areawide Methyl Bromide Alternatives Program. In the wine grape (Vitis vinifera var. Cabernet Sauvignon) plot experiments, soil nematodes and yield were measured. The data indicates a positive fumigation effect on yield and reduction in nematodes. Relatively low yields were found in the non-fumigated field plots and the low rate bare soil plots. In the raisin grape (Vitis vinifera var. Selma Pete) grower field trial, results showed lower yield values in the untreated control than in all fumigated crop rows. The two Telone C35 treatments showed similar yield to the methyl bromide control. Two field trials and laboratory experiments were conducted from June 2011 through June 2012 on emission reduction and efficacy improvement in soil fumigation. One trial was conducted in an annual crop field. Data on emission and soil fumigant were collected from the field tarped with totally impermeable film (TIF) and in tarp-edge areas. Results were reported at meetings and submitted to regulatory agency to assist in modeling efforts for regulation development. Another trial was conducted in a perennial field. Emission reduction by TIF and the effect of using reduced rates and carbonation (adding carbon dioxide to fumigant and using it as a dispersant in application) under TIF on fumigant distribution in soil and efficacy on nematodes, pathogens and weeds were investigated. A laboratory study was conducted on the degradation of several important fumigants affected by application rates. Research data were presented at growers and scientific meetings with three manuscripts in preparation. Results on emission reduction and efficacy improvement from soil fumigation were summarized and posted on the website of Pacific- Area Wide Program for Methyl Bromide Alternatives (http://ucanr. org/sites/PAWMBA/Emissions_Projects/Emission_Reduction/). This research continues to determine field effective fumigation rates under TIF. Accomplishments 01 Emission reduction by TIF and tarp-cutting time determined in large fiel trial. Tarping fumigated fields with low permeability films such as commercial product TIF (totally impermeable film) can significantly redu emissions, but can also increase fumigant residence time in soil and wou require extended tarp-covering durations to reduce potential exposure of workers and bystanders to fumigants. In collaboration with university researchers and industry as well as regulatory agency, a large field stu was conducted in 2011 and determined the effect of TIF on emission reduction and tarp-cutting time. Comprehensive data on emission reductio and fate and transport of fumigants in soil were collected in an 8-acre field fumigated with a mixture of chloropicrin and 1,3-dichloropropene (Pic-Clor 60). Low emission flux was measured throughout tarp-covering o 16 days with total emission loss <10%, and < 1% at the tarp edges. Emission flux upon tarp-cutting increased, but was substantially lower than 5 or 6 days of tarp covering. This study demonstrated the ability o TIF to significantly reduce fumigant peak flux and total emissions and required longer tarp-cutting time for using TIF. 02 Fumigant degradation varies with application rate. Low permeability tar effectively retain soil fumigant under tarp to reduce emissions while increasing concentrations in soil. This leads to the potential of using reduced fumigant rates to control soil pests. However, there is a significant knowledge gap on the relationship between fumigant concentration in soil and rates of degradation. A laboratory study was conducted to determine degradation rates of several important methyl bromide alternatives including 1,3-dichloropropene, chloropicrin, and dimethyl disulfide in five soils. Data show degradation of these fumigan is highly dependent on both the chemical and application rate. Fumigant degradation rates decrease significantly with increased application rate for chloropicrin and dimethyl disulfide, but much smaller changes are observed for 1,3-dicnloropropene compounds. The findings indicate fumiga degradation rates affect effective fumigant application rates under low permeability tarps. 03 TIP tarp and carbonation to reduce fumigation rate. The benefits of usin reduced rates for satisfactory pest control with TIF tarp was evaluated soil fumigation for perennials that require deep injection and effective dispersion of fumigants to control pests throughout soil profile. TIF ta and carbonation techniques were tested in a field trial on fumigant emission, fate, and distribution in soil as well as efficacy to determin the potential of using reduced chemical input. TIF was proven to reduce emissions >95% relative to bare soil while standard PE tarp reduced emissions ~30%. TIF significantly increased fumigant concentration or concentration-time exposure indices at 15 cm depth relative to the PE fi Reduced 2/3 fumigant rate under TIF showed the possibility to provide effective nematode control in soil profile, but the improvement on fumigant distribution by carbonation is inconclusive and relies on more field tests. This research continues to provide information on effective use of soil fumigants while minimizing environmental impact for many perennial crops. 04 Etiology of calla lily root pathogen. Thirty-nine isolates of Pythium sp were recovered from diseased roots of calla lily taken from multiple locations in production fields and tested for pathogenicity in a greenhouse test. All the pathogenic isolates were characterized using PC amplification and restriction digestion of the Cyclooxygenase-1 & 2 gene Thirty-five of the isolates were pathogenic and expressed the same genotype; the non-pathogenic isolates exhibited different genotypes. The data suggest the Pythium isolates from these multiple locations are identical; identification of this isolate down to species is in progress This work will facilitate rapid identification and quantification of a serious calla lily pathogen which impacts grower decisions of soil fumigation.
Impacts
(N/A)
Publications
- Jhada, A., Gao, S., Gerik, J.S., Qin, R., Hanson, B. 2012. Effects of surface seals and application shanks on nematode, pathogen and weed control with 1,3-dichloropropene. Pest Management Science. 68(2):225-230.
- Wang, D., Yates, S.R., Gao, S. 2011. Chloropicrin emissions after shank injection: Two-dimensional analytical and numerical model simulations of different source methods and field measurements. Journal of Environmental Quality. 40:1443-1449.
- Cabrera, A., Wang, D., Schneider, S.M., Hanson, B. 2012. Subsurface drip application of methyl bromide alternative fumigants for controlling nematodes in replanted grapevines. Pest Management Science. 68:773-780.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Test emerging methyl bromide alternative chemicals for their efficacy in controlling various soilborne plant pathogens in cut flowers and other ornamental crops. Test methyl bromide alternative chemicals, rates, and application methods to meet California certification standards for nematode-free production of tree, vine, and rose nurseries. Develop various application methods, soil amendments, and physical barriers to reduce the emissions and enhance efficacy of the chemical alternatives to methyl bromide. Develop integrated weed control strategies using combinations of methyl bromide alternative fumigants with herbicides and non-chemical management techniques to improve weed control. Approach (from AD-416) Research techniques will include extraction of soil fungal pathogens and nematodes, isolation and identification, population assessment and identification of native weeds, in-situ measurements of fumigant emissions and fumigant gas dispersion in soils, and determining impacts of various combinations of fumigant formulation and surface containment on efficacy and emission reductions. Experimental platforms will range from laboratory microcosms, soil columns, greenhouse pots, to small field plots and demonstration-scale field trials. Stakeholder participation in planning and implementation of research trials will be crucial. Outcomes from these research activities will be transferred to the stakeholders. Formerly 5302-13220-003-00D (12/07). Evaluation of pathogen control by methyl bromide alternatives were made in field trials in grower cooperator fields. Ornamental crop field trials using steam and dimethyl disulfide (DMDS) as methyl bromide alternatives were conducted in Oxnard, CA. Multiple soil assays from the DMDS field and a micro plot experiment were completed. An ornamental crop field trial on methyl bromide alternatives using chloropicrin and 1, 3- dichloropropene and low-permeable tarps was initiated in Moss Landing, CA. Pathogen assays of soil samples from the Watsonville field site and a greenhouse trial for a soilless substrate strawberry project were completed and results were compiled. A study on the etiology of the root rot disease of calla lily was initiated in the Moss Landing area. Pythium spp. isolates were collected from diseased calla lily roots from production fields. The isolates were tested for pathogenicity in a greenhouse assay and the pathogenic isolates were molecularly evaluated by polymerase chain reaction (PCR) and restriction enzyme digestion profiles to determine identity. Nematode control and crop response were measured from three ongoing grape replant fumigation field trials. Soil samples were collected from 5- 60 cm depth from each treatment plot and analyzed for type and number of resident nematodes. Because the fumigation treatment was applied in 2008- 2009, grape yield was measured as a crop response variable for the three field trials. Nematode control and crop response were also measured from the post plant DMDS trial on grapevines. Soil samples were collected from each DMDS treated plots (and the untreated control plots) and analyzed for nematode species and densities. Crop response measurements included yield and stomatal conductance from the grapevine leaves to determine the health or potential phototoxicity effect on the vines. Three field trials were conducted from fall 2010 through June 2011. The potential for reducing fumigant emissions and improving pest control efficacy was determined using a totally impermeable film (TIF) tarp at reduced fumigation rates. The first trial was conducted in California and determined the effect of reduced rates under TIF on fumigant soil distribution and efficacy against nematodes, pathogens and weeds in a perennial fumigation setting. The second trial was conducted in Florida in a raised-bed field prior to planting tomato and tested the combination of carbonation and TIF use on fumigant emissions and fumigant concentration changes in soil. The third trial was conducted in California in an 8-acre field covered with TIF and measured fumigant soil distribution, emission, and movement at tarp-edge areas. Sample analyses and data compiling were completed for first two trials and are on-going for the third trial. Accomplishments 01 Dimethyl disulfide (DMDS) as a methyl bromide alternative for pathogen control. DMDS is a potential methyl bromide alternative for pre-plant soil fumigation; however, limited data are available for its efficacy in pathogen control. ARS scientists in Parlier, CA, in a sunflower field trial in Oxnard, CA, found that pathogen densities of Fusarium oxysporum were reduced by 94% with methyl bromide (MB) compared to 80% with DMDS. Pythium spp. was reduced by 99% with MB compared to 98% with DMDS. Verticillium dahliae was reduced by 60% with MB and 94% with DMDS. Neith fumigant controlled Phytophthora cactorum. The research generated important data which demonstrated that control of soil-borne pathogens b the two fumigants was dependent on the target organism, and DMDS has efficacy for the control of soil-borne pathogens for the production of c flowers on the central coast of California. 02 Etiology of calla lily root pathogen. There is a lack of understanding genetic composition of soil pathogens in ornamental crops. Field and a greenhouse studies were conducted by ARS scientists at Parlier, CA where 39 isolates of Pythium spp. were recovered from diseased roots of calla lily form multiple locations in production fields and tested for pathogenicity in a greenhouse test. All the pathogenic isolates were molecularly characterized by PCR amplification and restriction enzyme digestion of the Cyclooxygenase-1 & 2 genes. Thirty-five of the isolates were pathogenic and expressed the same genotype; the non-pathogenic isolates had different genotypes. These data suggest that the pathogens from these multiple locations were identical. The identity of the pathog is still being investigated, but it may be a never before identified species. Effective management requires knowledge of the pathogen complex 03 Nematode control with reduced rates of Telone C35 under totally impermeable film (TIF). Replanting of perennial orchards and tree and vine nurseries in California depend on soil fumigation for production an delivery of nursery crops free of economically important plant parasitic nematodes as required under the California Department of Food and Agricultural�s Nursery Stock Nematode Control Program. ARS scientists in Parlier, CA, conducted field trials in 2009-2010 to test nematode contro under TIF using reduced application rates of Telone C35. The efficacy of both full and half rates of Telone C35 in the fall 2009 trial was 100% against citrus nematodes and pin nematodes at soil depths up to 90 cm. I the fall 2010 trial, the efficacy on citrus nematodes at 15 cm soil dept was 100% under TIF and 95% under the standard high density polyethylene (HDPE) when only one quarter rate of Telone C35 was applied. Also in the 2010 trial, 100% efficacy was found for root-knot nematodes at 90 cm soi depth. These results indicate that lower (than the label rate) fumigatio rates can be used, under TIF, without compromising the nematode control efficacy. 04 Fumigant emission reduction under totally impermeable film (TIF). TIF w shown to prevent fumigant penetration in the laboratory, however, no reliable field data supports the claim. Field tests were conducted by AR scientists in Parlier, CA to determine the ability of TIF for reducing fumigant emissions. The TIF tarp reduced 1,3-dichloropropene emissions t as low as 0.1% of applied amount in a field trial conducted in spring 20 Greater than 90% emission reduction was obtained in an earlier trial fr broadcast fumigation. Surging emission upon tarp-cutting is a concern, which was addressed in the most recent June 2011 field trial in Californ The research generated important data which will assist regulatory agencies in developing regulations on the safe use of TIF tarp. 05 Enhanced fumigant soil concentration and pest control under totally impermeable film (TIF). TIF is claimed to retain fumigant gases in soil yet data are not available on the increased resident time when TIF is us under field conditions. A field trial was conducted by ARS scientists in Parlier, CA in fall 2010 to determine improved pest control efficacy for perennial crops. Treatments included TIF and the standard high density polyethylene (HDPE) tarp in combination with different fumigation rates (full, half, and quarter rate) of Telone C35. Fumigant retention time an soil concentration increased, under TIF, which resulted in higher soil concentration-time exposure indices than that under the HDPE. This led t 100% pest control on nematodes and pathogens under either full or half rates of Telone C35 under TIF. Results indicate that TIF has the potenti to offer a long-term solution for reducing environmental impact of soil fumigation and improving efficacy. 06 Weed control using dimethyl disulfide (DMDS) and reduced rates of Telone C35 under totally impermeable film (TIF). DMDS is a potential methyl bromide alternative chemical and TIF is a potential replacement for the standard high density polyethylene (HDPE) for pre-plant soil fumigation, however, limited data are available on weed control. ARS scientists in Parlier, CA in a sunflower field trial in Oxnard, CA fumigated with DMDS and lower weed densities (37.0/m2) were found compared to methyl bromide plots (51.5/m2) or the untreated control (127.5/m2). In a Telone C35 tri in Parlier, CA plots covered with TIF tarp under full rate resulted in t lowest weed biomass, followed by TIF-half rate and HDPE-full rate. The highest weed biomass was from the non-fumigated control and the HDPE-hal rate had a weed biomass as high as the control. DMDS has efficacy for th control of weeds and reduced fumigation rates can be used for weed contr under TIF.
Impacts
(N/A)
Publications
- Gao, S., Hanson, B.D., Qin, R., Wang, D., Yates, S.R. 2010. Comparisons of surface sealing methods in emission reduction from soil fumigation using field plot tests. Journal of Environmental Quality. Available on line: Nov 2010, doi:10.2134/jeq2009.0422.
- Cabrera, A., Wang, D., Schneider, S.M., Hanson, B. 2011. Effect of potential methyl bromide alternatives on plant parasitic nematodes and grape yield under vineyard replant conditions. American Journal of Enology and Viticulture. 62(1):42-48.
- Hanson, B., Gao, S., Gerik, J.S., Shrestha, A., Qin, R., Mc Donnald, J.A. 2011. Effects of emission reduction surface seal treatments on pest control with shank-injected 1,3-dichloropropene and chloropicrin. Crop Protection Journal. 30(2):203-207.
- Wang, D., Gao, S., Qin, R., Browne, G.T. 2010. Lateral movement of soil fumigants 1,3-Dichloropropene and Chloropicrin from treated agricultural fields. Journal of Environmental Quality. 39:1800-1806.
- Wang, Q.X., Wang, D., Tang, J., Wei, S., Yan, D.D., Zhang, H., Wang, F.Y., Guo, M., Cao, A. 2010. Distribution and emission of chloropicrin applied as gelatin capsules. Journal of Environmental Quality. 39:917-922.
- Gao, S., Hanson, B.D., Wang, D., Browne, G.T., Qin, R., Ajwa, H., Yates, S. R. 2011. Methods evaluated to minmize emissions from preplant soil fumigation. California Agriculture. 65(1):41-46.
- Qin, R., Gao, S., Ajwa, H., Sullivan, D., Wang, D., Hanson, B.D. 2011. Field evaluation of a new plastic film (Vapor SafeTM) to reduce soil fumigant emission and improve distribution in soil. Journal of Environmental Quality. 40: 1195-1203.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) Test emerging methyl bromide alternative chemicals for their efficacy in controlling various soilborne plant pathogens in cut flowers and other ornamental crops. Test methyl bromide alternative chemicals, rates, and application methods to meet California certification standards for nematode-free production of tree, vine, and rose nurseries. Develop various application methods, soil amendments, and physical barriers to reduce the emissions and enhance efficacy of the chemical alternatives to methyl bromide. Develop integrated weed control strategies using combinations of methyl bromide alternative fumigants with herbicides and non-chemical management techniques to improve weed control. Approach (from AD-416) Research techniques will include extraction of soil fungal pathogens and nematodes, isolation and identification, population assessment and identification of native weeds, in-situ measurements of fumigant emissions and fumigant gas dispersion in soils, and determining impacts of various combinations of fumigant formulation and surface containment on efficacy and emission reductions. Experimental platforms will range from laboratory microcosms, soil columns, greenhouse pots, to small field plots and demonstration-scale field trials. Stakeholder participation in planning and implementation of research trials will be crucial. Outcomes from these research activities will be transferred to the stakeholders. Formerly 5302-13220-003-00D (12/07). Laboratory dose response studies with acrolein and dimethyl disulfide were completed for control of various soilborne pathogens and weeds. Pathogen control evaluations were made on cooperating methyl bromide alternatives field trials. Ornamental crop field trials using steam as a methyl bromide alternative were initiated in Nipomo, Carlsbad, and Oxnard, CA. An ornamental crop field trial on methyl bromide alternatives using dimethyl disulfide was initiated in Oxnard, CA. Data analysis and report writing were carried out on two multi-year fumigation projects in vineyards and nematode control assessments using various methyl bromide alternative treatments. A manuscript was completed and will be submitted in 2010. Crop response and nematode control efficacy were also measured from three ongoing grape replant field trials. A new study was initiated to test dimethyl disulfide for controlling nematodes in grapes. A greenhouse and a companion field study was initiated to determine nematode control in strawberries using substrate media and landscape fabrics. Emission reduction studies from soil fumigation were conducted through laboratory experiments and field trials. A soil column study was completed to investigate the relationship between soil water content and fumigant emissions in three different textured soils (sand, sandy loam and loam). Data for all three soils were compiled and a manuscript is in preparation. The data show how increasing soil water content up to field capacity affects 1,3-dichloropropene and chloropicrin emissions (flux and cumulative emission loss). A laboratory batch experiment was also initiated to determine fumigant persistence in soils from different application rates. Three field trials were conducted to evaluate the potential of a new low permeable tarp (totally impermeable film or TIF) to reduce emissions, improve fumigant distribution in soil profile, and/or reduce application rates. A report was prepared and a manuscript is being developed. Two field trials using small field plots were conducted in the San Joaquin Valley to determine the potential of TIF tarp to reduce emissions, improve fumigant distribution in soil and reduce fumigant application rate for perennial orchards and nurseries. Sample analyses or data compiling are on-going for these two trials. Ten herbicide trials in tree and rose nurseries established in 2009 were completed. Weed control and crop safety evaluations of pendimethalin, oryzalin, and dithiopyr which were generally safe to nursery stock and controlled many weed species. Relatively new or reformulated products including: indaziflam, penoxsulam, sulfosulfuron, halosulfuron, prodiamine, oxyfluorfen, also were evaluated in small-scale nursery tests. Accomplishments 01 Methyl bromide alternatives for Gladiolus production. Methyl bromide so fumigation has traditionally been used for Gladiolus production in California. Field trials were conducted by ARS scientists in Parlier, C to test methyl bromide alternative chemicals in Gladiolus production. A chemical treatments reduced the pathogen populations in both the drip an the shank trials compared to the untreated controls except for Telone C3 which did not perform well for control of Fusarium oxysporum in the shan trial. Bulb yield from the alternative treatments was generally comparable to the standard methyl bromide/chloropicrin treatment. Overa pathogen and yield seemed to be slightly better in the shank treatments compared to the drip treatments. From these results, it appears that a successful Gladiolus bulb crop can be grown with these alternative treatments. 02 Controlling soil pathogens with steam. Steam is a possible non-chemical methyl bromide alternative for killing soilborne pathogens; however, the are no field data to support this potential benefit. Field trials were carried out by ARS scientists in Parlier, California to apply steam via drain tile or spike hose to control soilborne plant pathogens. Compared untreated control soil, populations of Fusarium oxysporum and Pythium species were not significantly different in soils immediately after stea treatment with the spike hose. Fusarium populations at 4 months after steam treatment with the drain pipe were significantly lower in one of four trials than the untreated control. This research indicated a mixed success with steam to control these soil pathogens. 03 Effect of dimethyl disulfide on soil pathogens and nematodes. Dimethyl disulfide (DMDS) is a potential methyl bromide alternative for pre-plant soil fumigation; however limited data are available on its efficacy against soil fungal pathogens, weeds, and nematodes. Laboratory experiments were conducted by ARS scientists in Parlier, California to determine the critical dose of DMDS needed to provided adequate pest control. Nematode control was very good at reasonable rates and exposur times. Poor fungi and weed control was observed at all DMDS concentrations. This research indicates that DMDS can be a potential methyl bromide alternative for nematode control but not for fungi and weeds. 04 Methyl bromide alternatives for grape replant. Methyl bromide soil fumigation is often required during replantation of a new vineyard. In eight-year grape replant trial, ARS scientists in Parlier, CA found that 3-dichloropropene plus chloropicrin, iodomethane plus chloropicrin, and propargyl bromide generally controlled root-knot and citrus nematodes similar to methyl bromide. However, only propargyl bromide treatments h grape yield equivalent to methyl bromide during the first four years aft treatment. Rootstock selection had a profound effect on nematode populations; the root-knot resistant rootstock �Freedom� kept nematode numbers low regardless of preplant fumigation treatment. Where this particular race of root-knot nematode is the major replant problem, use a resistant rootstock may reduce the need for preplant fumigation; howev other replant problems such as different nematodes or soil-borne pathoge may still exist. 05 Fumigant emissions affected by soil type and water content. Soil fumigation is practiced across different soil types and soil moisture conditions; however, the effects of differences in soil texture and wate content on atmospheric emissions are not well understood. The relationship between soil type, water content, and fumigant emissions wa examined by ARS scientists in Parlier, California. Increasing water content up to field capacity reduced peak emission rate, delayed emissio occurrence time, and reduced total emissions. This effect appeared to b more significant in fine-textured than in coarse-textured soils. This finding is useful for growers and fumigation practitioners to develop effective agricultural practices towards reducing fumigant emissions. 06 Low permeable films reduce fumigant emissions. A new low permeable film referred to as totally impermeable film or TIF, effectively reduced fumigant emissions in laboratory tests; however, no field data are available. One large field trial was conducted by ARS scientists in Parlier, California to test the new film for reducing fumigant emissions under field conditions. The TIF reduced peak emission rate up to 10 tim lower than that from the standard polyethylene (PE) film. Over a 6-day field covering period, the total emission loss was reduced to below 2% o total fumigant applied compared to 30% emission with the PE film. Howev the emission surge upon cutting the TIF tarp was much higher than with the PE film indicating that a longer waiting time would be needed to reduce potential exposure risks. The research showed that using this ne film will help improve buffer zone restrictions and enable many fields t be fumigated under the newly amended United States EPA regulations. 07 Herbicide crop safety in perennial woody nurseries. Weed control is an important concern for production of woody nursery crops in California, however, phytotoxicity information is often not available for existing and new herbicides. ARS scientists in Parlier, California conducted 2- year field trials to determine the most promising herbicides. The herbicides pendimethalin, thiazopyr, and dithiopyr can be safely used in the nurseries. The herbicide oxyfluorfen was differentially phtotoxic t some nut tree rootstocks in the nursery. A series of sulfonylurea herbicides were phytotoxic in tree nurseries. The herbicide foramsulfur was not phytotoxic to a peach rootstock. The results of these herbicide evaluations contribute to the selection and adoption of new weed control strategies in perennial nurseries.
Impacts
(N/A)
Publications
- Wang, D., C. Rosen, L. Kinkel, A. Cao, N. Tharayil, J. Gerik. 2009. Production of methyl sulfide and dimethyl disulfide from soil-incorporated plant materials and implications for controlling soil-borne pathogens. Plant Soil. 324:185-197.
- Suduan Gao, Ruijun Qin, Bradley D. Hanson, Nishanth Tharayil, Thomas J. Trout, Dong Wang and James Gerik Effects of Manure and Water Applications on 1,3-Dichloropropene and Chloropicrin Emissions in a Field Trial. J. Agric. Food Chem., 2009, 57 (12), pp 5428�5434.
- Wang, D., G. Browne, S. Gao, B. Hanson, J. Gerik, R. Qin, N. Tharayil. 2009. Spot fumigation: fumigant gas dispersion and emission characteristics. Environ. Sci. Technol. 43:5783-5789.
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) Test emerging methyl bromide alternative chemicals for their efficacy in controlling various soilborne plant pathogens in cut flowers and other ornamental crops. Test methyl bromide alternative chemicals, rates, and application methods to meet California certification standards for nematode-free production of tree, vine, and rose nurseries. Develop various application methods, soil amendments, and physical barriers to reduce the emissions and enhance efficacy of the chemical alternatives to methyl bromide. Develop integrated weed control strategies using combinations of methyl bromide alternative fumigants with herbicides and non-chemical management techniques to improve weed control. Approach (from AD-416) Research techniques will include extraction of soil fungal pathogens and nematodes, isolation and identification, population assessment and identification of native weeds, in-situ measurements of fumigant emissions and fumigant gas dispersion in soils, and determining impacts of various combinations of fumigant formulation and surface containment on efficacy and emission reductions. Experimental platforms will range from laboratory microcosms, soil columns, greenhouse pots, to small field plots and demonstration-scale field trials. Stakeholder participation in planning and implementation of research trials will be crucial. Outcomes from these research activities will be transferred to the stakeholders. Formerly 5302-13220-003-00D (12/07). Significant Activities that Support Special Target Populations Dose response studies with acrolein in the lab have been completed. Laboratory experiments are currently being conducted to test efficacy of dimethyl disulfide (DMDS) for controlling various soilborne plant pathogens. Pathogen control evaluations were made on cooperating methyl bromide alternatives field trials led by unit members. Ornamental crop field trials on methyl bromide alternatives in Nipomo, Moss Landing, Oxnard, and Carlsbad, CA were completed. Field fumigation trials documenting nematode control with methyl bromide alternatives were completed and four new fumigation trials were established at the USDA research station or at cooperating nurseries. In open-field perennial crop nurseries, shank-injected, fumigants with plastic tarps generally provided better nematode control than drip- applied materials or untarped applications. Iodomethane:chloropicrin treatments generally provided nematode control as good as 1,3- dichloropropene but not as good as methyl bromide. Soil column studies were carried out to investigate the relationship between soil water content and fumigant emissions in three different textured soils (sand, sandy loam and loam). Data for a loam soil were complete and experiments for comparing with other two textured soils are on-going. Results indicate that increasing soil water content up to field capacity can result in linear reduction in emission flux in a loam soil. Reduction of emission flux was more profound than reduction of cumulative emission loss. Reduction of emission flux is significant to improve the buffer zone requirement during fumigation while reducing total emissions helps address volatile organic compound (VOC) issues in improving air quality in California. Four field trials were conducted to evaluate fumigant emission reductions using subsurface drip, spot-drip, strip-shank, modified shank vs. broadcast shank applications, low permeable tarps, and surface soil water or amendment treatments. Post-water treatments with sprinklers can effectively reduce peak emission flux than cumulative emission loss. Surface soil amendment with composted manure alone without water treatments can not always result in reduced emissions. Virtually impermeable films (VIF) can reduce emission flux and cumulative emission loss significantly as well as improve pest control. Further research is planned for testing more flexible low permeable tarps. This research continues to provide solutions to effective use of soil fumigants and minimize their negative environmental impacts. Ten new screening trials were initiated in cooperation with perennial crop nursery operations including producers of walnut, almond, stonefruit, and garden rose planting stock. Pre-emergence applications of pendimethalin, oryzalin, and dithiopyr were generally safe to nursery stock and controlled many weed species. Rimsulfuron, flumioxazin, oxyfluorfen, sulfentrazone, imazosulfuron provided even better weed control at the expense of variable crop safety. Relatively new or reformulated products including: indaziflam, penoxsulam, sulfosulfuron, halosulfuron, prodiamine, oxyfluorfen, etc., have been evaluated in small- scale nursery tests. Technology Transfer Number of Web Sites managed: 1
Impacts
(N/A)
Publications
- Qin, R., S. Gao, D. Wang, B.D. Hanson, T.J. Trout, and H. Ajwa. 2009. Relative effect of soil moisture on emissions and distribution of 1,3- dichloropropene and chloropicrin in soil columns. Atmospheric Environment. 43:2449�2455.
- Schneider, S.M., B.D. Hanson, J.S. Gerik, A. Shrestha, T.J. Trout, S. Gao. Comparison of Shank-and-Drip-Applied Methyl Bromide Alternatives in Perennial Crop Field Nurseries. 2009. HortTechnology. 19:331-339.
- Guo, M., and S. Gao. 2009. Degradation of methyl iodide in soil: effects of environmental factors. J. Environ. Qual. 38:513-519.
- McDonald, J.A. S. Gao, R. Qin, B.D. Hanson, T.J. Trout, and D. Wang. 2009. Effect of water seal on reducing 1,3-dichloropropene emissions from different soil textures. Journal of Environmental Quality. 38: 712-718.
- Hanson, B.D., A. Shrestha, D.L. Shaner. 2009. Distribution of Glyphosate- Resistant Horseweed (Conyza Canafensis) and Relationship to Cropping Systems in the Central Valley of California. Weed Science. 57:48-53
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Progress 10/01/07 to 09/30/08
Outputs
Progress Report Objectives (from AD-416) Test emerging methyl bromide alternative chemicals for their efficacy in controlling various soilborne plant pathogens in cut flowers and other ornamental crops. Test methyl bromide alternative chemicals, rates, and application methods to meet California certification standards for nematode-free production of tree, vine, and rose nurseries. Develop various application methods, soil amendments, and physical barriers to reduce the emissions and enhance efficacy of the chemical alternatives to methyl bromide. Develop integrated weed control strategies using combinations of methyl bromide alternative fumigants with herbicides and non-chemical management techniques to improve weed control. Approach (from AD-416) Research techniques will include extraction of soil fungal pathogens and nematodes, isolation and identification, population assessment and identification of native weeds, in-situ measurements of fumigant emissions and fumigant gas dispersion in soils, and determining impacts of various combinations of fumigant formulation and surface containment on efficacy and emission reductions. Experimental platforms will range from laboratory microcosms, soil columns, greenhouse pots, to small field plots and demonstration-scale field trials. Stakeholder participation in planning and implementation of research trials will be crucial. Outcomes from these research activities will be transferred to the stakeholders. Formerly 5302-13220-003-00D (12/07). Significant Activities that Support Special Target Populations Laboratory experiments were conducted to determine critical dose of acrolein to control several soilborne plant pathogens. Dose response of Agrobacterium tumefaciens to several other chemicals was also determined. One field trial on methyl bromide alternatives for cut-flowers has been completed in Carlsbad, CA, and four others are underway in Soledad, Nipomo, Santa Maria, and Oxnard, CA. New laboratory trials to determine critical dose of dimethyl disulfide (DMDS) for controlling various soilborne plant pathogens are underway. A series of field trials were completed on testing low rate MeBr applications under low permeability tarp in perennial crop nursery systems. In a single crop cycle, low rates of MeBr and 1,3- dichloropropene (1,3-D) under low permeability film were as effective as standard MeBr treatments for controlling plant parasitic nematodes while weed control tended to decrease with alternatives. Several fumigation experiments were initiated at the USDA facility and in cooperating nursery fields to test the impact of surface seal treatments (water seals, plastic films) on the nematode and weed control efficacy with 1,3-D and chloropicrin (CP). Although data analysis is ongoing, preliminary results suggest a strong effect of surface seal treatment on enhancing weed and nematode control in the upper soil layers. A large field trial was conducted in Oxnard, CA for testing the efficiency of two low permeable plastic tarps, virtually impermeable film (VIF) and semi-impermeable film (SIF) on reducing fumigant emissions in strawberry production. A standard polyethylene (PE) film with or without water applications in furrows was included for comparison. Emissions of 1,3-D and CP from top of the beds and furrows were measured using dynamic flux chambers. Total emission loss from the VIF and the SIF tarped fields was approximately 60% of that from the PE field. The preliminary results demonstrated that low permeable films were effective in reducing emissions. Water seal in furrows in the PE tarped field did not reduce total emissions, compared to the no water seal treatment, due to the low emission flux from the furrows. Additional data analysis is ongoing. Thirteen herbicide screening trials were initiated in cooperation with four perennial crop nursery operations (walnut, almond, stonefruit, and garden rose production) throughout the Central Valley of California. All treatments were applied to fumigated fields. Pre-emergence applications of pendimethalin, oryzalin, and dithiopyr were generally safe to nursery stock and controlled many weed species. Several other herbicides such as rimsulfuron, flumioxazin, sulfentrazone, imazosulfuron provided even better weed control at the expense of variable crop safety. Further research on the interaction between fumigation and herbicide treatments as well as herbicide application rate, timing, and nursery crop response is ongoing. NP308, Component 1. Technology Transfer Number of Web Sites managed: 1
Impacts
(N/A)
Publications
- Qin, R., S. Gao, J.A. McDonald, H. Ajwa, S. Shem-Tov, and D.A. Sullivan. 2008. Effect of plastic tarps over raised-beds and potassium thiosulfate in furrows on chloropicrin emissions from drip fumigated fields. Chemosphere. 72:558�563.
- Shrestha, A., B.D. Hanson, K.J. Hembree. 2008. Glyphosate-resistant hairy fleabane(Conyza bonariensis)documented in the Central Valley.Calif. Agric. 62:116-119.
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