Efficacy of Various Application Methods of Fluensulfone for Managing Root-knot Nematodes in Vegetables.

Fluensulfone is a new nematicide in the flouroalkenyl chemical group. A field experiment was conducted in 2012 and 2013 to evaluate the efficacy of various application methods of fluensulfone for control of Meloidogyne spp. in cucumber (Cucumis sativus). Treatments of fluensulfone (3.0 kg a.i./ha) were applied either as preplant incorporation (PPI) or via different drip irrigation methods: drip without pulse irrigation (Drip NP), pulse irrigation 1 hr after treatment (Drip +1P), and treatment at the same time as pulse irrigation (Drip =P). The experiment had eight replications per treatment and also included a PPI treatment of oxamyl (22.5 kg a.i./ha) and a nontreated control. Compared to the control, neither the oxamyl nor the fluensulfone PPI treatments reduced root galling by Meloidogyne spp. in cucumber. Among the drip treatments, Drip NP and Drip +1P reduced root galling compared to the control. Cucumber yield was greater in all fluensulfone treatments than in the control. In a growth-chamber experiment, the systemic activity and phytotoxicity of fluensulfone were also evaluated on tomato (Solanum lycopersicum), eggplant (Solanum melongena), cucumber, and squash (Curcurbita pepo). At the seedling stage, foliage of each crop was sprayed with fluensulfone at 3, 6, and 12 g a.i./liter, oxamyl at 4.8 g a.i./liter, or water (nontreated control). Each plant was inoculated with Meloidogyne incognita juveniles 2 d after treatment. There were six replications per treatment and the experiment was conducted twice. Foliar applications of fluensulfone reduced plant vigor and dry weight of eggplant and tomato, but not cucumber or squash; application of oxamyl had no effect on the vigor or weight of any of the crops. Typically, only the highest rate of fluensulfone was phytotoxic to eggplant and tomato. Tomato was the only crop tested in which there was a reduction in the number of nematodes or galls when fluensulfone or oxamyl was applied to the foliage compared to the nontreated control. This study demonstrates that control of Meloidogyne spp. may be obtained by drip and foliar applications of fluensulfone; however, the systemic activity of fluensulfone is crop specific and there is a risk of phytotoxicity with foliar applications.