Studies On Resistance Of Alternaria Alternata (Fries) Keissler To Fungicides

Effect of 19 kinds of fungicides on inhibiting the growth of Alternaria alternata (Fries) Keissler were investigated. The results showed that the fungicides, such as myclobutanil, propiconazole, prochloraz, tebuconazole, and diniconazole could strongly inhibite the growth of the fungus.When the iprodione-resistant mutants of Kl-1, EGS35-193, and L-2 were cultured successively 8 times on PDA with iprodione, their characteristic of iprodione-resistance was unchanged, indicating the stability of the mutants.Iprodione-resistant mutants could be constantly isolated only from approximately 46% of the wild-type isolates incubated on PDA with iprodione. The mutants of Alternaria alternata resistant to iprodione occurred at very high frequency, indicating that there was a potential for a rapid population shift from sensitivity to resistance.The mutants of Aalternata were transferred to PDA with other chemicals, the results indicated that the iprodione-resistant mutants responded similarly to the wild type isolate when grown on PDA containing chlorothalonil, fenbuconazole, and diniconazole,and the iprodione-resistant mutants were sensitive to difenoconazole, mancozeb, myclobutanil,flusicazole, prochloraz, and propiconazole, only growing less aerial mycelia; The iprodione-resistant mutants were stronger resistant than the wild type to thiabendazole; These resistant mutants were sensitive to thiabendazole, so that iprodione and thiabendazole were applied shifted in turn could decrease the opportunity of the iprodione-resistant mutant arising.