Location: Water Management Research
Title: Spot drip application of dimethyl disulfide as post-planting treatment for the control of plant-parasitic nematodes and soilborne pathogens in grape production Authors
Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 9, 2013
Publication Date: N/A
Interpretive Summary: Dimethyl disulfide (DMDS) is a sulfur volatile compound that has zero ozone depletion potential. Pre-plant treatment with DMDS has shown an adequate performance for ornamental plants, strawberry and sugar beet production. However, it has not been demonstrated whether DMDS could be utilized as a post-plant fumigant to control nematodes and pathogens without causing phytotoxic effects. In this investigation, post-plant drip fumigation to established Thompson Seedless grape vines did not show phytotoxicity symptoms. All the plant parameters evaluated were not statistically different from the untreated vines. Post-plant application of DMDS effectively controlled citrus, pin, ring, root-knot nematodes. For the ecto or external parasitic nematodes such as citrus, pin, and ring nematodes the dosage needed was 60 kg/ha treated area while for the endo or internal parasitic root-knot nematodes a relatively higher dosage at 231 kg/ha would be needed. Both rates were below the commonly applied rate of 347 kg/ha used in pre-plant soil fumigation. In contrast to nematodes, post-plant drip fumigation with DMDS did not provide substantial control of the soilborne pathogens Pythium ultimum and Fusarium oxysporum. It is likely that soilborne pathogens have different sensitivities to DMDS. The yield of Thompson Seedless grape was higher at the lowest DMDS rate used in the field trial than the untreated control or none of the other rates evaluated. This outcome may be attributed to the possibility that the low rate DMDS treatment was able to control nematodes without affecting beneficial organisms in soil. In contrast, the higher rates likely not only suppressed the nematode populations but also inhibited beneficial organisms in the soil.
Technical Abstract: BACKGROUND: Plant-parasitic nematodes and soilborne pathogens can reduce the overall productivity in grape production. Not all grape growers apply soil fumigants before planting and there is no single rootstock resistant to all nematode species. The aim of this investigation was to evaluate the effect of dimethyl disulfide (DMDS) applied as a post-planting treatment against soilborne plant-parasitic nematodes, pathogens, and on yield in established grape vines. RESULTS: In microplot and field trials, post-plant fumigation with DMDS controlled citrus (Tylenchulus semipenetrans), root-knot (Meloidogyne spp.), pin (Paratylenchus spp.), and ring (Mesocriconema xenoplax) nematodes in established Thomson Seedless grape vines. However, DMDS did not control the soilborne pathogens Pythium ultimum and Fusarium oxysporum. No indications of phytotoxicity were detected after post-plant fumigation with DMDS. In the field trial grape yield was significantly higher in the lowest DMDS rate but no difference in other rates, compared to the untreated control. CONCLUSION: Post-plant fumigation with DMDS controlled plant parasitic nematodes in established grape vines but had less action against soilborne pathogens. Low rates of DMDS were sufficient for nematode control, increased the yield, and probably without affecting beneficial soil organisms. Further research on evaluating potential effect of DMDS against beneficial soil organisms is needed.