On Management The Resistence Of Sclerotinia Sclerotiorum To Carbendazim

The research on how to manage the resistance of Sclertinia sclerotiorum to carbendazim occurred in some regions of Jiangsu, Hubei and Zhejiang provinces. The sensitivity test of S.sclerotiorum to triadimefon, dimethachlon, diniconazole, procymidone and propiconazole had the better effects in vifro as well as the good therapy effect in viva. While diethofencarb had the better effect to resistance- carbendazim isolates. The mixture thob of diniethachlon+thiram+triadimefon with synergistic biological response (SR1 .88) was used for field plot test. At the dosage of 2700glhm2of 24.8%a.i. thob, it had treatment effect up to 80.9% compared with its respective components. 25%MBC was used at the rate of 4500g/hxn2 had only got the effectiveness with 40.3%. The resistance risk of dimethachlon, the main component of the thob was evaluated. Dimethachlon resistant mutants were obtained at 2.4 X I 0~æ¡° o-~ frequency when its mycelia pieces were irradiated with 95% lethal dosage UV- ray in PDA medium. The mutants were still able to grow regularly on the PDA medium amend with 5-10 ~1 g/ml (LR),I0-50 j.?gImI (MR),100 ii g/ml (HR)dimethachlon. All the mutants had positive cross resistant to procymidone of DCF. The capacity of linal growth of mycelium of mutants on PDA medium exhibited no difference from their parents, though the dry-weight of mycelia of mutants was lower. 85.7% of mutants had pathogenicity while 100% parent isolates did. Mutants had the weaker capacity of produce sclerotium generation than that of those wild sensitive isolates. None of resistant sclerotia of mutants was monitored after mycelia piece suspection of mutants mixtureed with wild sensitive isolates which were sprayed during the period of full bloom of the rape. These results showed mutants had lower fitness than wild sensitive isolates. Procymidone caused less electrolyte leakage of the sensitive cultures isolate than that of resistant strains. The change of cell membrane permeability of the 4 sensitivity isolate was smaller than that of the resistant isolate. The activity of PAL of mutant MN6I was high than that of parent isolate PNO61 in the situation of nutrient deficieny or in the 5 u glint or 20+ p. glint dimethachlon treatment solution.