Induction of resistance to fusarium wilt of melon using herbicides trifluralin and acetochlor

Effect of herbicides, trifluralin and acetochlor, on the mycelial growth of Fusarium oxysporum f.sp. melonis (FOM) and Fusarium wilt disease of melon was investigated. Both herbicides inhibited the mycelial development of FOM on the solid medium depending on the concentration of herbicides. However trifluralin increased the mycelium intensity on the solid medium, and therefore increased mycelial dry weight of FOM in the liquid medium correlated with herbicide concentration. Acetochlor had more inhibitory effect on the colony growth of FOM than those of trifluralin did. Acetochlor in the liquid medium also decreased mycelial dry weight of FOM correlated with herbicide concentration. Both herbicides trifluralin and acetochlor, at application dosage/2 (trifluralin; 96 [il/m2 and acetochlor; 168 u.l/m2) had highest effect on the wilt disease incidence with 62.4% and 55% effectiveness, respectively. However application dosages (192 u,l/m2 and 336 ul/m2) were also diminished disease incidence but application dosagex2 (384 ul/m2 and 672 u.l/m2) increased disease incidence. Extracts of these plants had inhibitory effect on the germ tube of FOM spores compared to control plant extracts. Extracts from the plants exposed to the herbicides at application dosage/2 most effectively inhibited the germ tubes of spores, this was followed by application dosagex2 and application dosage, respectively. Key Words: Melon, Fusarium wilt, Induced resistance, Herbicide.