| Gray mould caused by Botrytis cinerea is one of major fungal diseases in the world, its control mainly relies on application of synthesized fungicides. Now, resistance to benzimidazoles, dicarboximides, pyrimidines and N-phenylcarbamate fungicides occurs worldwidely in B. cinerea. The good solution to the problem of resistance to fungicides in B. cinerea is to introduce and apply novel fungicides (no positively correlated cross-resistance exists between the novel fungicides and resistance-existing fungicides), or develop and use mixing fungicide with synergistic action or additive action against B. cinerea. Fludioxonil, fluazinam and SYP-Z048 are novel fungicides with high efficacy to control gray mould, the joint fungitoxicity of their mixtures directly decides if they can be used in tank mixtures or used as packed mixed formulations.Therefore, the resistance to currently used systemic fungicides in B. cinerea was tested; the cross resistance relationship between the novel botryticides and current used fugicides was studied; The novel fungicides with good inhibitory activity against the dominated isolates (multiple resistant) were screened and the joint-toxicity of the mixtures of the novel fungicides against B. cinerea was tested and the fungicide combinations and their ratios of mixtures with synergistic action against B. cinerea were determined. Morever, the fungicide combinations without antagonistic effects were screencd and the miscibility of the novel fungicides was determined; the mechanism of synergy of fungicide mixtures was studied primarily. The results of research as follows:In this study, the resistance of conventional fungicides and the cross-resistance of the new fungicides aginst B.cinerea was tested.And then joint-toxicity of fungicide mixtures containing screened fungicides. The field efficacy trials were taken to screen more fungicide mixtures to control tomato B.cinerea.And preliminary exploration of synergistic mechanism had also be taken.Main results are following:1. Resistance to main botryticides of B. cinerea collected from major tomato production regions of Hebei and Shandong provinces was detected. The results showed that resistance of B. cinerea occurred widely to the systemic fungicides, such as carbendazim, iprodione, diethofencarb and pyrimethanil. The multiple resistant isolates to the 4 botryticides (carbendazim, iprodione, diethofencarb and pyrimethanil) accounted for 68.63%. No positively correlated cross-resistance exists between fluazinam and pyrimethanil, carbendazim, iprodione or boscalid.2. Cucumber cotyledon spray inoculation test, a bioassay method fit for testing fungitoxicity of various fungicides against B. cinerea was developed. was formulation,which suitable for test of toxicity of fungicides. With this bioassy method, the novel botryticides with high fungitoxicity (SYP-ZO48, boscalid, fludioxonil, fluazinam) were screened out.3. The obviously synergistic combinations and mixing ratios of the novel fungicides, such as SYP-Z048 + fludioxonil ( 1:7 ) , SYP-Z048+ fluazinam ( 1:7 ) and fludioxonil+fluazinam(1:3), were determined by joint fungitoxicity test of the mixtures of the novel fungicides, the synergistic ratios (SR, Calculated by Wadley formula) were 8.56,9.31 and 2.32, respectively.4. The results of the field efficacy trials showed that the tank mixtures of boscalid with fludioxonil, difenoconazole, chlorothalonil, pyrametostrobin or SYP-Z048 gave higher efficacy in control of gray mould than the single fungicides. boscalid 250 g.ai/hm~2 + SYP-Z048 50 g.ai/hm~2 was syngergistic effects with SR (Calculated by Abbott formula) of 1.1 . The tank mixtures of Bacillus subtilis BAB-1 5×109/mL AS with fludioxonil 50% WP 18000 g.ai/hm~2+ 90 g.ai/hm~2, 18000 g.ai/hm~2 + 60 g.ai/hm~2, 18000 g.ai/hm~2 + 45 g.ai/hm~2, 12000 g.ai/hm~2 + 60 g.ai/hm~2 ) gave excelent efficacy (from 91.52% to 93.71%) in controlling of tomato gray mould, and showed additive effect.5. The results of synergism mechanism showed that synergism of SYP-Z048+ fludioxonil(1:7), SYP-Z048+ fluazinam(1:7) were related to the increased cell membrane permeability and the strengthend lipid peroxidation of Botrytis cinerea mycelium,but not related with the inhibitory activity against the respiration of conidia and the ergosterol synthesis in mycelium of B. cinerea. Synergism of fludioxonil+fluazinam(1:3) was related to the cell membrane permeability increased,the inhibiting the respiration of conidia strengthend, but unrelated to lipid peroxidation and the ergosterol synthesis of mycelium. |
PDF Full Text Request