Effect of isoprothiolane on the infection process of Pyricularia oryzae.

Isoprothiolane (IPT), diisopropyl 1, 3-dithiolane-2-ylidenemalonate was tested for its effect on vegetative growth and infection process of Pyricularia oryzae Cav. Mycelial growth in a glucose-yeast extract liquid medium was inhibited completely at 20ppm, and partially at 10 and 5ppm. Abnormal hyphae like chlamydospore cells were frequently formed in the presence of IPT. IPT at 2ppm did not affect conidial germination and appressorium formation, but almost completely inhibited penetration when treated at the pre-germination stage. Treatment of the fungus with IPT at different stages of the fungal infection process revealed that IPT inhibits penetration and growth of infection hyphae rather than conidial germination and appressorium formation.