Antifungal Effect And Action Mechanism For Seed Treatment Of Fusarium Wilt Of Cucumber

Twelve kinds of fungicides were tested with Fusarium oxysporium in indoor toxicity,from which selected Flusilazole,difenoconazole and thiram which have different modes of action.Mix of any two kinds,test of indoor toxicity,selection of seed-dressing in formulation,safety to cucumber,effect to Fusarium oxvsporium,the toxic effect to fungi and the stability of seed-dressing were researched.The results are as following:1.The results of indoor toxicity tested on the different fungicides against Fusarium oxysporium show that of the twelve tested pesticides,40%Flusilazole EC,10%difenoconazole DG and 50%thiram DC had better antifungal effect on Fusarium oxysporium,which inhibition reached to 90.8%,82.9%,82.0%respectively.2.The results of indoor united toxicity test show that Flusilazole,difenoconazole and thiram had better effects on Fusarium oxysporium if we mixed with two kinds properly.When the formulation rates of Flusilazole and difenoconazole,Flusilazole and difenoconazole,thiram and difenoconazole,thiram and Flusilazole,thiram and Flusilazole are 24:1,49:1,40:10,48:2,49:1 and their CTC are 335.7,848.6,200.5,388.5,368.5 respectively.3.Comparing with the contrast,the observed results show the hypha grew abnormally in the plate including single and mixed agents.There was a lot of main hypha expended and protruded outside on the plate including difenoconazole and Flusilazole 1.0μg/ml,thiram and Flusilazole 1.0μg/ml agents.Some main hypha on the plate including 1.0μg/ml difenoconazole produced melting holes.Part of new hypha on the plate including 0.2μg/ml Flusilazole produced expansion like string from the top.The hypha on the plate including difenoconazole and Flusilazole 1.0μg/ml shrank lightly.4.Experiments were done on the antifungal compositions of seed-dressing in the Pesticide Room Plant Protection Department of Gansu Agricultural Academy of Sciences.The results show:the agents of three seed-dressings are 2%Flusilazole and difenoconazole FS (Flusilazole 0.04,Difenoconazole 1.96);10%thiram and difenoconazole FS(Flusilazole 8.40,difenoconazole 1.60);20%thiram and Flusilazole FS(thiram 18.80,Flusilazole 1.20)respectively.5.The results of the experiment on germination rate of indoor seeds show:every 1kg seeds dressed with 20g to 100g 20%Flusilazole and difenoconazole FS,10%thiram and difenoconazole FS,20%thiram and Flusilazole FS.The average number of healthy seedlings,the average germination rate and the length of the leaf sheath of the control had no obvious difference with the control of the three single agents and contrast.The results show:three seed-dressings have safe effects on cucumber within experiment does.6.In the experiment with potted plants,every 1kg seeds dressed with 2%Flusilazole and Difenoconazole FS,20%thiram and Flusilazole FS,10%thiram and difenoconazole FS 60g to 100g have better effects on Fusarium oxysporium.The effects are 78.4%to 88.4%,73.3%to 83.8%and 62.7%to 77.8%.However,the contrast chemicals are 50% thiram DC,10%difenoconazole DG,40%Flusilazole EC which have effects of 44.9%to 63.2%,49.8%to 84.1%,49.3%to 89.3%respectively on Fusarium oxysporium.By LSR test,there is no obvious different effects between the doses of three seed-dressings and the doses of contrast agents——difenoconazole,Flusilazole and thiram,but all are higher than the other controls.7.In low temperature experiment and hot store experiment,three seed-dressings did not emerge layer.This shows that the nature of seed-dressing is stable.