Effect of oxamyl and fenamiphos on egg hatching, motility, and root penetration of Tylenchulus semipenetrans
AbstractThe effect of oxamyl and fenamiphos on egg hatching, motility and penetration of juveniles of Tylenchulus semipenetrans into roots of sour orange (Citrus aurantium) rootstock were investigated under controlled conditions in a growth chamber. Both chemicals were used at 10,50, 100, and 500 flg a.Uml of water concentrations. Egg hatching between 0.0-5.7 % was obtained when eggs were exposed to concentrations exceeding 100)lg a.Uml water of ox amyl or fenamiphos for seven or fourteen days, compared to 22.1 and 36.1 % in the controls, respectively. However, maintaining the eggs for two weeks in distilled water following the seven- or fourteen-day exposure to all tested concentrations of both pesticides, significantly increased egg hatching, suggesting that temporary inhibition occurred. Sin1ilarly, oxamyl and fenamiphos at 100 )lg a.Uml of water reduced (P = 0.05) juvenile motility to 55.3 and 18.8%, respectively, compared with 89.5% in the control. Also, root penetration rate was reduced (P = 0.05) to 3.4 and 2.5% when juveniles were exposed to oxamyl or fenamiphos at 100 )lg a.Uml of water, respectively, compared with 9.4 % in the control.