Indoor Toxicity Test And Field Efficacy Of Different Fungicides Against Erwinia Amylovora

Pyrus sinkiangensis is a local pear species with high quality and unique characteristics in Xinjiang.Because of its good quality,it is sold domestically and overseas.It is an important part of Xinjiang speciality fruit industry.However,in recent years,a destructive plant disease,pear fire blight,caused by Erwinia amylovora,has appeared in pear trees.and has seriously restricted the healthy development of pear industry.In order to prevent and control the damage caused by pear fire blight,two methods,which were bacteriostatic circle method and turbidimetric method,were used to determine the indoor virulence,to screen effective pesticides for safety test,and to carry out the field safety test and field efficacy test of different pesticides.My study aimed at screening out better fungicides for controlling pear fire blight from different fungicides,and providinge scientific basis for the prevention and control of pear fire blight.1.The indoor toxicity of different fungicides to E.amylovora was determined by the inhibition zone method and turbidimetric method.The results of inhibition zone method showed that 12%thixomethadone WG,3%thixomethadone microemulsion and 6%Zhongshengmycin solubilizer had better inhibitory effect on the E.amylovora,with EC₅₀of 28.4458 mg/L,43.3265 mg/L and 88.6913 mg/L,respectively;The EC₅₀of 40%Chunlei·thiazole zinc SC was 340.0747 mg/L,the EC₅₀of 2%chunleimycin and 20%thiazole zinc SC were 424.0616 mg/L and 473.1399 mg/L respectively,and the EC₅₀of 20%thiabendazole copper SC was 5118.1528 mg/L;The results of turbidimetric method were basically coincide with that of inhibition zone method.12%thixolone WG,3%thixolone microemulsion and 6%zhongshengsu solubilizer had better inhibitory effect on the E.amylovora,with EC₅₀of 29.2187 mg/L,40.7039 mg/L and 83.3098 mg/L respectively,followed by 2%chunleimycin WG,40%Chunlei·thiazol zinc SC,20%thiazol zinc SC and20%thiazol copper SC,The EC₅₀were 400.9225 mg/L,315.5131 mg/L,410.5469 mg/L and 349.6537mg/L,respectively.the test results showed that:12%thixolone WG,3%thixolone microemulsion and 6%zhongshengsu soluble agent all had good antibacterial effect on the E.amylovora of E.amylovora in the two indoor determination methods.This finding can provide reference for the prevention and control of pear fire blight.2.The leaf spray method was used to test the safety of three kinds of pear cultivars which were Korla fragrant pear,Xinli 7 and Dangshan pear.The results showed that three pear varieties were sprayed with fungicides at young fruit stage.The symptoms of plant reaction were regularly observed at 1,3,5,7,10and 21 days after spraying.3%thiametholone,12%thiametholone,6%Zhongshengmycin,2%chunleimycin,40%Chunlei·thiazol zinc,20%thiazol zinc and 20%thiabendazole copper were safe for three different pear varieties.The recommended dosage in the field was 1,2 times and 2 times of that in the field.Spraying 4 times of the dose did not cause any harm,and had no effect on the growth of three pear varieties.3.The field efficacy test of different fungicides on pear fire blight in 2019 showed that the control effect of 12%thixolone WG was the highest,reaching 84.94%,followed by 2%chunleimycin water solution,6%Zhongshengmycin soluble agent,20%thiazolyl zinc suspension agent and 3%thixolone microemulsion,reaching 80.40%and 76.82%,72.93%and 70.44%respectively,The control effect of 20%thiabendazole copper SC and 40%Chunlei·thiazole zinc SC was the lowerest,reaching 45.91%and60.26%respectively.The results of field trials of Different Fungicides against pear fire blight in 2020 were basically accorded with those in 2019.The control effect of 12%thixolone WG was the highest,reaching82.98%,followed by 3%thixolone microemulsion,2%chunleimycin and 6%zhongshengsu,reaching73.40%,72.34%and 70.97%,respectively.The control effect of 40%Chunlei·thiazole zinc SC and 20%thiabendazole copper SC was the lowerest,reaching 62.92%,54.84%and 46.07%,respectively.According to the results of field efficacy trials in two years,12%thixolone WG,3%thixolone microemulsion,6%Zhongshengmycin soluble agent and 2%chunleimycin water agent had better control effects on pear fire blight,since all of them reached more than 70%of efficacy They could be used as control agents for pear fire blight in production.