Epidemiological Studies of Rice Blast Disease Caused by Pyricularia oryzae Cavara

Sporulation potential and conidia release phase of Pyricularia oryzae on lesions under the natural conditions were measured in 1985 and 1986 leaf blast seasons. The amount of conidia produced in lesions on detached leaves and conidia released under the field condition were reached peak at days after lesion appearance. The maximum numbers of conidia produced and released were 16,200 and 15,900, respectively. Conidia release under the natural conditions lasted for 30 days.