VINEYARD REPLANT - PERFORMANCE OF METHYL BROMIDE ALTERNATIAVES OVER TIME.

Authors: Schneider, Sally; Trout, Thomas; Browne, Greg; AJWA, HUSEIN - UC DAVIS; SIMS, J. - UC RIVERSIDE

Submitted to: Methyl Bromide Alternatives and Emissions Research Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2004
Publication Date: 10/31/2004
Citation: Schneider, S.M., Trout, T.J., Browne, G.T., Ajwa, H.A., Sims, J. 2004. Vineyard replant - performance of methyl bromide alternatiaves over time.. Methyl Bromide Alternatives and Emissions Research Conference Proceedings. pp 8-1 to 8-5.

Interpretive Summary: Methyl bromide has commonly been used to control Replant Disorder when planting a new vineyard into the same field from which an old vineyard was removed. With the ban on import and manufacture scheduled for Jan. 1, 2005, growers need alternatives to methyl bromide for perennial crops that demonstrate efficacy beyond the first growing season in order to remain competitive. Three field trials were conducted at the USDA station under conditions similar to commercial vineyard replant conditions. The studies show that two chemicals, 1,3-dichloropropene and iodomethane, each alone or combined with chloropicrin, provided control of plant parasitic nematodes similar to methyl bromide. Therefore these might be alternatives to methyl bromide for nematode control, but there are restrictions. Iodomethane is not yet registered by the US Environmental Protection Agency or the California Department of Pesticide Regulation, so it is not available to commercial growers. 1,3-D is limited to a maximum amount in each township (a 36 square mile area). If the maximum has already been reached no more can be used until the next year. Our field studies also evaluated the benefit of leaving the old vineyard fallow for up to 3 years before planting. On Thompson Seedless, the most common grape grown in the San Joaquin Valley of California, there was no significant benefit in reducing nematode populations by leaving the ground fallow up to three years. The benefit of fallow combined with nematode resistant rootstocks varied with the rootstock. This would only be an acceptable treatment if the resistance available matched with the all of the kinds of nematodes in a particular vineyard.

Technical Abstract: Methyl bromide has commonly been used to control Replant Disorder when planting a new vineyard into the same field from which an old vineyard was removed. With the ban on import and manufacture scheduled for Jan. 1, 2005, growers need alternatives to methyl bromide for perennial crops that demonstrate efficacy beyond the first growing season. After six growing seasons, a field trial in Parlier, CA demonstrated that drip-applied 1,3-dichloropropene (1,3-D) and shank-injected iodomethane (IM) controlled plant parasitic nematodes comparably to methyl bromide. Harmony, a rootknot-resistant rootstock, remained free of rootknot nematode, Meloidogyne spp., but supported high populations of citrus nematode, Tylenchulus penetrans. Yield of Thompson Seedless and Merlot on Harmony was greatest in plots treated with 1,3-D and IM and least in plots treated with a one-year fallow followed by a cover crop. In a second field trial, the benefit of fallowing up to three years varied by variety/rootstock after four growing seasons. There was no significant reduction in nematodes on Thompson Seedless. There was numerical, but not significant, reduction of rootknot nematode on Teleki 5C. There was no significant differences in yield across length of fallow, untreated, and methyl bromide treatments. In a third field trial, after three growing seasons, IM, 1,3-D + chloropicrin, and propargyl bromide provided comparable nematode control to methyl bromide. Although 1,3-D and IM have shown nematode control comparable to methyl bromide in these trials, there are restrictions on their use. IM is not yet registered and therefore is not available to commercial growers. Use of 1,3-D is limited in California by township caps.