Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: November 6, 2002
Publication Date: November 6, 2002
Citation: SCHNEIDER, S.M., TROUT, T.J., BROWNE, G.T., AJWA, H.A., SIMS, J. VINEYARD REPLANT DISORDER - RESULTS AFTER 1, 2, AND 4 GROWING SEASON.. PROCEEDINGS OF INTERNATIONAL RESEARCH CONFERENCE ON METHYL BROMIDE ALTERNAT. 2002. Interpretive Summary: "Replant disorder" is a general term for the lack of vigor in a newly replanted vineyard as compared to vines planted in "non-vineyard" soil. Fumigation with methyl bromide prior to replanting is commonly used to alleviate the problem. Alternatives are needed to insure the health and vigor of replanted vineyards. Field trials to evaluate potential alternatives for perennial crops must determine efficacy of pathogen control not only at the time of planting the new vineyard, but must assess the on-going performance of the methyl bromide alternatives during the early growth and fruiting years. After four growing seasons, iodomethane and the 1,3-D appear to be good alternatives to methyl bromide for vineyard replant when both rootknot and citrus nematode are present. The Harmony rootstock continues to support only minimal populations of the rootknot nematode, even in the untreated plots, but supports higher populations of the citrus nematode than either Thompson Seedless or Teleki 5C rootstock. After 2 growing seasons, nematode populations in some long-term fallow treatments are lower than the untreated control, but not as low as in methyl bromide treated plots. After one growing season, several alternative chemicals resulted in nearly undetectable nematode populations, but vine growth was not as vigorous as in the methyl bromide treated plots. These studies indicate there are some promising alternatives to methyl bromide for vineyard replant.
Technical Abstract: Field evaluation of potential methyl bromide alternatives for perennial crops must determine not only efficacy of pathogen control at the time of planting the new vineyard, but also the efficacy of pest control and impact on crop growth and yield during the early growth and fruiting years. In 1998, 9 soil treatments were applied to a 65-year old grape replant trial. After 4 growing seasons, the drip-applied 1,3-D treatments achieved control comparable to methyl bromide of nematode populations for all nematode/rootstock combinations except for citrus nematode on Thompson Seedless in one 1,3-D treatment. With the exception of rootknot nematode on Thompson Seedless, iodomethane also controlled nematodes as well as methyl bromide. The rootknot nematode populations on nematode-resistant Harmony rootstock were nearly undetectable for all treatments. Thompson Seedless vines in the methyl bromide and all 1,3-D treatments were larger than vines grown in the non-chemical treatments. Vines grown in the iodomethane plots were intermediate in size. Yield in 2001 in the plots treated with methyl bromide was significantly greater than in plots treated with 1-year fallow + cover crop. Yield in all other treatments was intermediate. In 2001, 11 soil treatments were tested in an 85-year old grape replant trial. After 1 growing season, there were no significant differences in nematode populations in the untreated control, the herbicide, and the sodium azide treatments. Of the remaining treatments, all but the drip applied chloropicrin were comparable to methyl bromide in rootknot nematode control. Vines were pruned in February,2002. Methyl bromide and propargyl bromide plots had the heaviest pruning weights.