Toxicity And Mode Of Action Of Three Kind Of Volatile Compounds Against Botrytis Cinerea In Shandong Province

Gray mold caused by Botrytis cinerea is a kind of worldwide disease, which can infect many kinds of crops and cause serious reduction of output. Gray mold has become a serious disease on vegetable production in the protected area of north China. Now, people mainly spray chemical fungicide to control gray mold, but the B. cinerea is easy to develop resistance.It is report that gray mold has shown high resistance to the common fungicides such as carbendazol, procymidone, pyrimethanil and so on. Some studies found that many kinds of volatile compounds such as benzothiazole, trans-2-hexenal, 1-octen-3-ol had strong biological activity against B. cinerea, which had great potential in terms of control of plant diseases.This study determined the sensitivity of 73 gray mold strains in Shandong province to the three kinds of volatile compounds. Analysis the interactions between volatile compounds and common fungicides. Studied the action mode of volatile compounds and influence of virulence to B. cinerea. The results were as follows:1. The different resistance strains of B. cinerea in Shandong province were sensitive to benzothiazole, trans-2-hexenal and 1-octen-3-ol. The range of EC₅₀ values of benzothiazole was 0.38-1.08 μL/L, the mean EC₅₀ values was 0.62 μL/L; the range EC₅₀ values of trans-2-hexenal was 10.07-14.28 μL/L, the mean EC₅₀ values was 11.65 μL/L;the range EC₅₀ values of 1-octen-3-al was 17.07-19.46 μL/L, he mean EC₅₀ values was 18.31 μL/L. All three kinds of volatile compounds can completely inhibit mycelial growth of B.cinerea. The biological activity order was benzothiazole>trans-2-hexenal>1-octen-3-ol.2. The toxicity of benzothiazole and boscalid mixture was higher than boscalid used alone. The mixture of benzothiazole and procymidone had higher toxicity than procymidone used alone when the dosage of procymidone is low（under 50mg/L to resistant isolate and5mg/L to sensitive isolate）, and the difference was not significant when the dosage of procymidone is high（above 100mg/Lto resistant isolate and 10mg/Lto sensitive isolate）; there was no significant difference when benzothiazole mixed with pyrimethanil or carbendazol compare with pyrimethanil or carbendazol used alone. The toxicity of trans-2-hexenal mixed with pyrimethanil or boscalid was significant higher than pyrimethanil or boscalid used alone;trans-2-hexenal mixed with carbendazol or procymidone showed a lower toxicity thancarbendazol or procymidone used alone. The toxicity of 1-octen-3-ol mixed with common fungicides was significant higher than the fungicides used alone.3. The three kinds of volatile compounds showed significant therapeutic effect to cucumber gray mold, the control effect could reach 100% of benzothiazole at the dose of 4μL/L, of 1-octen-3-ol and trans-2-hexenal at the dose of 10 μL/L. Their order was benzothiazole>1-octen-3-ol>trans-2-hexeneal. By contrast, the protective effect of three kinds of volatile compounds was weak. The control effect of benzothiazole reached 92.98% at the highest dose of 8 μL/L, but the effects of the other doses were lower than boscalid which control effect was 84.21%. 1-Octen-3-ol and trans-2-hexenal showed less protective effect to the cucumber gray mold.4. Inoculating the B. cinerea fumigated by volatile compounds to the cucumber leaf, the ability that inhibit B. cinerea infection of three kinds of volatile compounds was benzothiazole>trans-2-hexenal>1-octen-3-ol, which showed that trans-2-hexenal has higher effect than 1-octen-3-ol.