Study On The Resistance Of Pyricularia Grisea To Tricyclazole

Fungicide tricyclazole can't inhibit mycelium grow and spore germinate.Only on the rice ,tricyclazole express control activity to P.grisea .So that,the sensitive measurement of tricyclazole can't adopt normal method. This paper studied the sensitive measurement of P. grisea to tricyclazole and studied the fungicide resistance monitor technique.The ability of creating spores has been compaired in seven different mediums.The results showed tomato medium was the best medium for creating rice blast spores.With the comparision of treatment model of the fungicide tricyclazole treatment of root-soaking was better than that of spraying .The control effect of root-soaking for 36h was the highest.The result of resistance was caculated according to the disease symptoms of the 2nd and 3rd leaves.The method of monitoring resistance of P. grisea to tricyclazole has been studied andthe model has been created. After rice seedings root-soaking, leave fragments were cut and placed onto 0.5%agar medium with 100ug/mL benzimidazole. After artificially inoculated with spores suspension (105spores/mL), the fragments were returned to moist climatic chamber to observe disease symptoms in 8 days. Comparison studying shows that the monitoring result was more stable and sensitive with leaf fragments treatment than whole seeding treatment.One hundred and thirty isolates from 4 different provinces had been moimtored,the results showed that the sensitive base line was 0.35u.g/mL and the resistance isolate has not been found even these isolates collected from where tricyclazole had been used for 10 years.The most sensitive isolate DY2 and the most not sensitive isolate F6 has been under tricyclazole pressure through 5 generations,the ECso has not showed going up.Through the resistance monitoring,we can think the tricyclazole can be continue used in the field.Techenicas of applying tricyclazole aganist rice blast and facts affecting the control effect were studied. The results showed that both of foliar spraying and root-soaking havecertain control effects. At the same concentration ,the control effect of root-soaking is higher. The control effect of tricyclazole could last as long as 7 - 10 days after leaf-spraying or root-soaking. Treatment with foliar spraying 3 days after the first applying tricyclazole could increase the control effect and elongate the lasting period of the control effect . The main effect of tricyclazole is preventive, and the minor one is curative. If the rice leaves were wounded ,or if it rained within 3 hours after foliar spraying ,the control effect would sharply decline. Through fungicide mixture selection,the mixture of tricyclazole and prochloraz(tricyclazole: prochloraz=4:l) was found better control effect than others.