Preliminary Study On Chemical Control And Biological Control Of Melon Wilt

Watermelon and muskmelon,as horticultural crops that can effectively increase the economic income of melon farmers,which play an important role in the adjustment of agricultural structure in China.However,Fusarium wilt of watermelon and Fusarium wilt of muskmelon are increasingly harmful to watermelons and muskmelons.In this study,fungicides and their mixtures were screened out,which had better inhibitory effect on Fusarium wilt of watermelon and muskmelon.At the same time,a strain of antagonistic bacteria was screened and its fermentation conditions were identified and optimized,which provided a theoretical basis for the control of watermelon and muskmelon wilt.which provided a theoretical basis for the chemical control and biological control of watermelon wilt and melon wilt.The result of this study are as follow:1.4 watermelon wilt strains HDXG-0;CLXG-1;DHXG-2;NAXG-3 and 4 muskmel on wilt strains SYTG-4;NATG-5;KQTG-6;DHTG-7,using mycelial growth rate screeni ng and spore germination methods for drug screening tests.The compounding test was c arried out according to the test results.The results showed that prochloraz 45% ME and myclobutanil 25% EC had better inhibitory effects on mycelial growth of pathogens to Fusarium wilt of watermelon and muskmelon,respectively.SYP-Z048 25% EC and azox ystrobin 250 g/L SC had better inhibitory effects on spore germination of pathogens to Fusarium wilt of watermelon and muskmelon,respectively.The above four agents were screened by proportional mixing method,and the synergistic coefficients of different prop ortions were calculated by Wadley method.prochloraz 45% ME and azoxystrobin 250 g/L SC were mixed with the mass ratio of 4:1,while SYP-Z048 25% EC and azoxystro bin 250 g/L SC were mixed with the mass ratio of 3:2 which had synergism and additi on effects on inhibition mycelial growth and spore germination of the Fusarium oxyspor um f.sp.niveum and Fusarium oxysporum f.sp.melonis.Furthermore,SYP-Z048 25% EC and azoxystrobin 250 g/L SC were mixed with the mass ratio of 2:3,1:1,4:1 also pla y synergies evaluation in inhibition effect for Fusarium oxysporum f.sp.niveum.The pot ted efficacy test was carried out on 5 compounding agents which had synergistic effects and additive effects on the inhibition of watermelon wilt and 2 compounding agents w hich had synergistic effects and additive effects on the inhibition of muskmelon wilt.Th e results showed that: The treatment effects of the mixed fungicide treatment were signif icantly higher than the single fungicide treatment.The preventive effect was more than 80% when each plant was irrigated with a mixture of 10 mL,which fungicide concentr ation was 1.5 g/L.2.A strain of bacteria JK9 with good antagonistic effect against Fusarium wilt of watermelon and muskmelon was screened by plate confrontation method and inhibition zone method.It was identified as Bacillus velezensis by morphology,physiology,biochemistry and molecular biology.The fermentation conditions of strain JK9 were optimized by single factor screening and multi-factor orthogonal test.The optimal nutrient medium combination was determined to be 2.00% glucose,0.50% peptone + yeast extract powder + sodium nitrate(2:2:1),0.18% KCl and 3.00% beef extract.The optimum culture conditions were as follows: initial pH 7,inoculation volume 5%,liquid volume 100 mL/250 mL,culture temperature 32℃,rotational speed 200 r/min,shake time 30 h.