苹果叶斑病病原菌鉴定及杀菌剂筛选

Identification of Apple Leaf Spot Pathogen and Screening of Fungicides

苹果叶斑病是苹果树上常见的病害之一,在苹果产区发生普遍且致病力较强,造成苹果树大量落叶,对苹果产量和品质造成了严重的影响。为了鉴定研究区苹果叶斑病的病原菌种类,筛选出有效杀菌剂,本研究对苹果发病叶片上的病原菌进行了离体培养、纯化并测定其致病性,对分离到的菌株进行形态学和分子生物学鉴定。利用带毒介质菌丝生长速率法测定该病原真菌对75%百菌清可湿性粉剂、43%戊唑醇悬浮剂等4种药剂的抑菌率和敏感性。结果表明,引起该地区的苹果叶斑病的病原菌是链格孢菌Alternaria alternata;4种化学药剂对病原菌均有抑制效果,4种药剂中EC_(50)值最小的为45%咪鲜胺水乳剂,其EC_(50)值为0.521 5 mg·L^(-1);最大的为75%百菌清可湿性粉剂,其EC_(50)值为1 080.19 mg·L^(-1);4种药剂相同浓度下抑菌率最高的为45%咪鲜胺水乳剂,最低的为75%百菌清可湿性粉剂,稀释2 000倍时抑菌率分别为82.76%和58.26%。因此,由链格孢引起的苹果叶斑病防治可优先选45%咪鲜胺水乳剂。

To identify the pathogen causing leaf spot of Malus pumila,samples of Malus pumila leaf spot were collected,and the isolated strains were isolated and identified using tissue separation method,morphology and molecular biology.The pathogenicity of the isolated strains was determined by mycelium plugs attachment method.The results showed that the pathogen causing apple leaf spot disease in this area was Alternaria alternata,which provided a reference for the prevention and control of leaf spot disease.Four kinds of chemical agents had inhibitory effects on pathogens.the results found that the EC_(50) of 45%prochloraz EW(EC_(50)=0.5215 mg·L)was the smallest and 75%chlorothalonil WP(EC_(50)=1080.19 mg·L)was the largest among the four agents.The highest inhibition rate of the four agents was 45%prochloraz EW,and the lowest inhibition rate was 75%chlorothalonil WP,when diluted 2000 times,the bacteriostatic rates were 82.67%and 58.26%,respectively.So 45%prochloraz EW could be preferentially selected for the prevention and control of apple leaf spot caused by Alternaria alternata.