EFFECTS OF BIOLOGICALLY-DERIVED PRODUCTS ON MOBILITY AND REPRODUCTION OF THE ROOT-LESION NEMATODE, <I>PRATYLENCHUS PENETRANS</I> , ON STRAWBERRY
Keywords: fenamiphos, nematicide, phytochemicals, plant-parasitic nematodes, organophosphate
AbstractPinkerton, J. N., and M. L. C. Kitner. 2006. Effects of biologically-derived products on mobility and reproduction of the root-lesion nematode, Pratylenchus penetrans, on strawberry. Nematropica 36:181-196. Seven biological products reported to have nematicidal activity were evaluated for suppression of Pratylenchus penetrans mobility in vitro and reproduction on 'Totem' strawberry plants. Mobility of nematodes was evaluated in vitro by exposing nematodes to a range of concentrations of products in aqueous solutions for 24, 48, and 72 h, followed by rinsing and incubating the nematodes for 24 h in deionized water. Nematodes exposed to deionized water or the organophosphate nematicide fenamiphos served as controls. During 72 h exposure in 70 µl/L a.i. solution of fenamiphos, >75% of nematodes were immobilized and 58% did not recover mobility in subsequent water incubation. Ninety percent of nematodes were immobilized during exposure to 1380 mg/L DiTera for 72 h, and 35% remained immobile after subsequent 24 h incubation in water. NatureCur, SLS-CA (Sodium lauryl sulfate-citric acid), and formulations of 3.5% thymol (Dominator and Promax) immobilized 45 to 70% of the nematodes, but mobility was restored by subsequent incubation in water. Sincocin, castor oil, and LCF (liquid compost factor) showed no activity. In greenhouse experiments, diluted products were applied as soil drenches at two or four week intervals, starting when strawberries were planted in soil infested with 1 P. penetrans/g soil, or four weeks after planting. Plant growth and nematode population densities were evaluated 16 and 20 weeks after planting in separate experiments. Applications that started at planting were more effective than those started four weeks after planting once nematodes had entered the roots. DiTera at 1380 mg/L and SLS-CA at 2857 µl/L applied at planting provided significant nematode suppression. However, SLS-CA stunted plant growth. No biological product was as effective as fenamiphos. Data suggest that multiple applications synchronized with host and nematode biology will be necessary to maintain efficacious concentrations of these biological products in agricultural soils.