|Ajwa, Husein - UC DAVIS|
Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: September 4, 2005
Publication Date: October 30, 2005
Citation: Schneider, S.M., Trout, T.J., Ajwa, H.A. 2005. Field evaluation of methyl bromide alternatives for vineyard replant.. Proceedings of International Research Conference on Methyl Bromide Alternatives. October 31 - November 3, 2005 Proceedings, pp 45-1 - 45-6. 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 import and manufacture of methyl bromide banned as of 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. Iodomethane, drip-applied Telone, and InLine appear to be good alternatives to methyl bromide for vineyard replant when both rootknot and citrus nematode are present. Iodomethane is not yet registered and use of 1,3-dichloropropene (in Telone and InLine) is restricted in California by township caps. Rootknot nematode populations on Harmony rootstock remain very low after 6 growing seasons, but populations of the citrus nematode are higher on Harmony than on either Thompson Seedless or Teleki 5C. Significant benefit in rootknot and citrus nematode population reduction from long-term fallow treatments for vineyard replant was no longer observed after five growing seasons.
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 in effect since Jan. 1, 2005, growers need alternatives to methyl bromide for perennial crops that demonstrate efficacy beyond the first growing season. After six growing seasons, the drip-applied 1,3-dichloropropene (1,3-D) and shank-injected iodomethane continue to demonstrate control comparable to methyl bromide of both the rootknot (Meloidogyne spp.) and citrus (Tylenchulus semipentrans) nematode populations for most treatment/nematode/ rootstock combinations. Citrus nematode populations on Thompson Seedless and Teleki 5C rootstock in plots subjected to chemical treatments were higher than in past years, but remained lower than populations in non-chemical treatments. The rootknot nematode populations on Harmony rootstock remained very low for all treatments, but the citrus nematode populations were highest on Harmony. Yield in the Thompson Seedless plots treated with iodomethane or 1,3-D delivered in 4 inches of water was significantly greater than in plots treated with 1-year fallow alone or followed by a 1,3-D treatment. After five growing seasons in a Long Term Fallow trial, there were no significant differences in rootknot or citrus nematode populations in one, two, or three-year fallow as compared to the untreated control. There was no significant difference in yield between treatments in own-rooted Thompson Seedless and Thompson Seedless on Harmony. In a 3rd trial, rootknot nematode control comparable to methyl bromide was achieved on Thompson Seedless with InLine and propargyl bromide and for citrus nematode with iodomethane + chloropicrin, propargyl bromide, and InLine. On the more resistant Freedom rootstock, iodomethane + chloropicrin, propargyl bromide and InLine treatments controlled rootknot and citrus nematodes comparable to methyl bromide. Nematode control on the 1103P rootstock was comparable to methyl bromide for iodomethane + chloropicrin and propargyl bromide. In a 4th trial, at the end of the first growing season the largest vines were grown in plots treated with methyl bromide for all variety/rootstock combinations and the smallest vines were grown in either the untreated plots or plots treated with sodium azide. Nematode populations on all variety/rootstock combinations after 2 growing seasons in plots treated with iodomethane + chloropicrin or 1,3-D + chloropicrin were comparable to methyl bromide. Rootknot nematode populations in azide treated plots were comparable to populations in the untreated control.