Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 22, 2011
Publication Date: November 18, 2011
Citation: 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. Interpretive Summary: An integrated approach to reduce negative impacts of plant parasitic nematodes in grape replant situations combines pre-plant fumigants and resistant plant rootstocks. Chemical fumigants with the potential to be used as alternatives to methyl bromide are usually shank applied for a broadcast fumigation. However, in order to reduce impact on the environment and decrease worker exposure to fumigants, these pesticides can be applied through drip irrigation systems. The aim of this study was to determine the effect of different drip applied fumigants on plant parasitic nematodes, plant vigor and grape yield in a replanted vineyard for seven years. Results showed that pre-plant fumigation using subsurface drip application followed by planting a tolerant/resistant rootstock provided sufficient control of plant parasitic nematodes during the vine establishment period in a replant situation. The sole use of a tolerant/resistant rootstock may be useful when only some root knot-nematodes are present. However, pre-plant fumigation will likely be necessary when a variety of plant parasitic nematodes are encountered due to the lack of a wide range of tolerance and resistance in a single root-stock.
Technical Abstract: Many grape growers in California use pre-plant fumigation to control plant parasitic nematodes to ensure uniform and healthy grapevine establishment in replant situations. One of the primary fumigants, methyl bromide, is being phased-out. A field study was conducted to evaluate an integrated approach combining drip-applied chemical alternatives to methyl bromide and tolerant/resistant rootstocks on plant parasitic nematodes, plant vigor and yield during the establishment seven-year period after replant. RESULTS: Pre-plant fumigation with 1,3-dichloropropene plus chloropicrin and iodomethane plus chloropicrin had generally similar nematode control as methyl bromide regardless of whether the replanted grapevine was a susceptible cultivar or a tolerant/resistant rootstock. Sodium azide was generally less effective than methyl bromide. The tolerant/resistant rootstocks provided adequate management of root-knot nematodes, but were inconsistent with regard to other nematodes. The combination of 1,3-dichloropropene plus chloropicrin generally enhanced vine vigor similar to methyl bromide. However, all plots treated with alternative fumigants produced less fruit yield than methyl bromide over the four years of evaluation. CONCLUSION: The integrated approach of using alternative chemicals to methyl bromide followed by planting a tolerant/resistant rootstock provided adequate management of plant parasitic nematodes during the vine establishment period. However, further research is required to control other components of the replant problem since grape yield in vines grown in the alternative treatments was lower than in methyl bromide.