Inoculation techniques used for inducing Rice false smut efficiently

Artificial inoculation techniques for false smut of rice (caused by Ustilaginoidea virens (Cooke) Takahashi) was studied under field condition. Inoculation with three inocula indicated that chlamydospores collected and kept at -20℃ last year could not cause false smut; thin wall conidia prepared from liquid culture could cause the disease, and higher concentration of conidia resulted in higher percentage of diseased panicles, the severest disease was caused by mixture of hypha fragment and thin wall conidia. Length of growing period of pathogen influenced inoculation effect. Among three inoculation stages of rice, the case inoculated 6-9 d before emergence of panicle resulted in optimum diseased effect. Among three inoculation periods on a day, the case inoculated at 4:00-6:00 pm. induced severest disease. Potato juice could increase percentage of diseased panicles when it was added to inoculum. The inoculation technique advanced in this paper could induced false smut efficiently, the optimum percentage of diseased panicles, disease index, number of spore balls in a panicle were 100%, 93.96, 110, respectively. The inoculation technique could distinguish differences of varietal resistance.