Author
 |
Pinkerton, John |
|
KITNER, MEGAN - OREGON STATE UNIVERSITY |
|
Submitted to: Nematropica
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/21/2006 Publication Date: 1/1/2007 Citation: Pinkerton, J.N., Kitner, M. 2007. Effects of biologically derived products on mobility and reproduction of the root lesion nematode, Pratylenchus penetrans, on strawberry. Nematropica. 36(2):176-190. Interpretive Summary: The root lesion nematode, Pratylenchus penetrans , is an economically important pest of agronomic and horticultural crops. Fenamiphos, an organophosphate nematicide, is the only pesticide registered for managing nematodes in plantings of raspberry and strawberry. Fenamiphos will not be manufactured after 2007, leaving the small fruit industries no options to control nematode damage in established plantings. Experiments were conducted to evaluate seven biological-based products in or near commercial production as replacements for fenamiphos. Nematode mobility was evaluated by exposing nematodes to a range of concentrations of products in aqueous solutions for 72 h, followed by rinsing and incubating the nematodes for 24 h in water. Most all nematodes were immobilized in the fenamiphos solution and did not recover mobility in subsequent water incubation. DiTera mobilized up to 90% the nematodes and 35% remained immobile after subsequent incubation in water. NatureCur, SLS, Dominator, and Promax immobilized 45-70% of the nematodes, but mobility was restored by subsequent incubation in water. Sincocin, castor oil, and LCF had no activity. In greenhouse experiments, diluted products were applied as soil drenches at two or four week intervals, starting when strawberries were planted in nematode infested soil, or four weeks after planting. Applications that started at planting were more effective than those started four weeks after planting once nematodes had entered the roots. DiTera and SLS applied at planting supressed nematodes significantly. 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 products. Technical Abstract: Biological products reported to have nematotoxic effects were evaluated for the suppression of P. penetrans mobility in vitro and reproduction on strawberry plants. Mobility was evaluated 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 the organophosphate nematicide fenamiphos or deionized water served as controls. During 72 h exposure in 70 ppm 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 ppm DiTera, and 35% remained immobile after subsequent incubation in water. NatureCur, SLS, and formulations of 3.5% thymol (Dominator and Promax) immobilized 45-70% of the nematodes, but mobility was restored by subsequent incubation in water. Sincocin, castor oil, and LCF had no activity. In greenhouse experiments, diluted products were applied as soil drenches at two or four week intervals, starting when strawberries were planted in nematode infested 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 and SLS applied at planting supressed nematodes significantly. However, SLS stunted plant growth. No biological product was as effective as fenamiphos. Data suggest that multiple applications synchronized with host and nematode biologies will be necessary to maintain efficacious concentrations of these products. |
