Risk Assessment And Control Effect Of Wheat Powdery Mildew To Cyflufenamid

Wheat powdery mildew is one of the common leaf diseases of wheat.When the disease is serious,it will cause serious yield loss or even failure.Due to the change of temperature,the overuse of control agents,and the change of farming system,powdery mildew has begun to move northward in China.Cyflutamide is a new kind of amide fungicide,which was researched and developed by the Cao Da company of Japan.The current literature shows that cyflutamide has a good control effect on powdery mildew.To evaluate the control effect of cyflutamide on wheat powdery mildew,the sensitivity of wheat powdery mildew to cyflutamide was determined by the pot culture method.The mutants were acclimated and the development of cyflutamide resistance of wheat powdery mildew was studied by comparing the biological characteristics and screening the common chemicals.Based on laboratory experiments,the control effect of cyflutamide on Wheat Powdery Mildew and its effect on wheat yield was determined under field conditions.1.67 isolates of wheat powdery mildew from 6 different wheat-producing areas were tested by pot culture method,and all of them were highly sensitive to cyflutamide.The results showed that there was no significant difference in the sensitivity of 67 isolates of wheat powdery mildew from Yantai,Shandong Province;Xinxiang,Henan Province;Shijiazhuang,Hebei Province;Guoyang,Anhui Province;Lijiang,Yunnan Province,and Ya’an,Sichuan Province.The coefficients of variation were 2.60,1.67,4.39,1.41,6.43,and 2.03,respectively.The sensitivity of each site was following the normal distribution.The sensitivity distribution of 67 strains of wheat powdery mildew ranged from 0.1199 to 0.9365 mg/L,and the average EC₅₀was 0.4982 mg/L.the normal test p-value of 67 strains of wheat powdery mildew was0.8969,and the sensitivity baseline was a continuous unimodal curve,which conformed to the normal distribution law.Therefore,it can be used as the sensitive baseline of Wheat Powdery Mildew in main wheat-producing areas.2.The results showed that the resistant strains were HBSJZ-Z-5 and HNXX-Z-5b y UV induction,and the resistance level was 14.36 and 8.78 respectively,and the mut ation frequency of resistant strains was 0.028%;three resistant strains were obtained b y continuous acclimation,namely HBSJZ-R-3,SDYT-R-3,and SDYT-R-7,and the mut ation frequency of resistant strains was 0.042%.The sensitivity of resistant strains and their parents to five used fungicides was azoxystrobin>pyrazoxystrobin>tebuconazole>carbendazim>Polyactin,and there was no cross-resistance with cyflutamide.In the ge netic stability of resistance,the resistance of the resistant strains could not be inherite d stably after 10 generations of continuous culture,but the EC₅₀was still higher than that of the corresponding parent strains.In the study of resistance biology of resistant strains,the sporulation and germination of resistant strains were lower than that of th eir parents.The pathogenicity of resistant strains was significantly lower than that of t heir parents after 5,7,and 9 days.The results showed that the resistance risk level o f cyflutamide wheat powdery mildew combination was 3-12,and the highest resistance risk was moderate.3.The best ratio of the registered agents,buconazole,carbendazim,and pyrazoletide,was selected to control wheat powdery mildew.The difference of control effect of two different wheat varieties was compared,which provided the reference for the control of Wheat Powdery Mildew in the field.The toxicity of three kinds of agents to powdery mildew and CTC of different proportions were measured by pot culture method,and a reasonable proportion was found out.The results showed that the three agents were the best in the wheat varieties of shannong16 and tenon 18 when the ratio of Carbendazim and tebuconazole was5:3,the CTC was 122.66 and 123.56;the ratio of tebuconazole and pyrazoletide was 2:1,and the synergistic effect was the best,CTC was 139.09 and 129.97;the ratio of Carbendazim and pyrazole was 1:1,and the synergistic effect was the best,CTC was 1:1 35.15 and 145.24.The best mix ratio of carbendazim,tebuconazole,and pyrazoletide was determined in this study,which could provide a reference for the mixture of wheat powdery mildew control agents and the alternative use of cyflutamide.4.The results of the wheat field test showed that 50 g/L cyflutamide EC at 25,30,40,50,60,and 100 m L/hm²could effectively inhibit the occurrence of Wheat Powdery Mildew in Ningyang and Feicheng of Shandong Province.The control effect of 50 g/L cyflutamide EC at25 m L/hm²was equivalent to that of 430 g/L tebuconazole SC,and the control effect reached the maximum at 100 m L/hm²;the control effect of 150 g/L benzovindiflupyr EC at 225m L/hm²and 300 m L/hm²was equivalent to that of 50 g/L cyflutamide EC at 50 m L/hm²and60 m L/hm²,which indicated that cyflutamide had excellent control effect on wheat powdery mildew.Compared with the wheat yield of Ningyang and Feicheng in Shandong Province,the1000 grain weight of 50 g/L cyflutamide EC at 25 m L/hm²,30 m L/hm²,40 m L/hm²,50m L/hm²,60 m L/hm²and 100 m L/hm²increased,and the 1000 grain weight of 150 g/L benzovindiflupyr EC at 300 m L/hm²reached the maximum,which had no significant difference with that of 50 g/L cyflutamide EC at 100 m L/hm².There was no significant difference between different treatments and blank control,indicating that different treatments had no effect on the number of panicles and grains per spike.In yield and yield increasing rate,wheat yield of different treatments was higher than that of blank control.