Study On Screening And Applying Mixture Of Pesticides For Controlling Rice False Smut

Rice False Smut,caused by Ustilaginoidea virens(Cke)Tak,is one of main rice spike diseases in the dee plant area,and becomes an epidemic disease and causes severe yield loss recently.This disease affects the quality of dee products as well as decreases yield loss.This paper aims at screening an optimum culture medium for culturing the pathogen of dee false smut ultimately.At the same time,we had screened the compound fungicide in order to controlling this disease.The study adopt 3 kinds of method for pathogen isolation.Our results showed that the Method of Vibroflotation is most effective method for isolation.We also test 6 kinds of culture mediums for the pathogen culturing,the results showed that the Wakimoto Toceshi is the best medium for Ustilaginoidea virens to produce chlamycladospores.Through laboratory bioassay test,we had tested the toxicity of A1,A2,B1,B2 and their mixtures to Ustilaginoidea virens.The results indicate that each have certain effects to inhibit the pathogen of rice false smut.The virulence of A1 and A2 is higher(ECS0=2.14 mg/L and 0.74mg/L respectively)than B1 and B2(EC50=204.17 mg/L and 213.8mg/L respectively).Both of the mixtures of A1 & B1 and A2 & B1 inhibited the growth of mycelium,but the synergism of the latter is more notable. Mixing the A2 and B1 according to different ratio(1:5,1:10)had enhancing effect (CTC is higher than 200 respectively).However,mixing A1with B2,or A2 with B2 had not enhancing effect.The results of field test indicate that the controlling effect of A1 & B1(1:4) EC with 40ml/667m~2,60ml/667m~2,80ml/667m~2 on Rice False Smut were 61.8%, 72.9%and 83.3%,respectively;The controlling effect of A2 & B1(1:5)WP with 50g/667m~2,75g/667m~2,100g/667m~2 on Rice False Smut were 45.8%,74.6%,89.5%.