Examination of chemical, biological, and cultural control measures of root-knot nematodes in lima beans

Date
2016
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University of Delaware
Abstract
Southern root-knot nematodes (Meloidogyne incognita-RKN) are among the most destructive plant pathogens and are infectious on a range of crops, including lima bean (Phaseolus lunatus), a crop vital to the Mid-Atlantic Region vegetable industry. Control of root-knot nematode (RKN) cannot be limited to crop rotation or the fallowing of fields due to an extensive host range and survival characteristics that enable the pathogen to persist in the soil, even in non-ideal conditions. In relatively recent years, the most effective chemical nematode controls, such as methyl bromide, organophosphate and carbamate nematicides, were found to be harmful to the environment and to non-target soil biota, leading to a reduction or even prohibition of their usage, spurring a revival in research to control RKN. ☐ In this research, the effects of new chemicals, biologicals, and cultural practices on RKN populations were examined. Chemical controls on RKN populations and lima bean plants were studied, in multiple greenhouse and microplot experiments. Emergence of lima bean seedlings was negatively affected by ethoprophos, but RKN galling and populations were significantly reduced, often as the best performing nematicide in the experiments. Two new nematicides, fluensulfone and fluopyram, reduced RKN galling compared to the untreated control. Spirotetramat, applied as a foliar treatment, performed equivalent to the control in every experiment (no significant effect). In addition, the use of biofumigant mustard and sorghum cover crops, which can reduce RKN levels by releasing compounds that react in the soil with an end-product resulting in natural fumigation, were investigated with findings that support the widespread use of ‘Dwarf Essex’ rapeseed in the region to control RKN. Cultural approaches also impacted RKN populations. Organic matter additions showed small but significant reductions in RKN galling with high rates of compost and chicken manure. Winter survival rates of RKN on common cover crops in the region was similar for all crops tested.
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