| Anthracnose,caused by diverse Colletotrichum species,is a very prevalent,serious fungal disease of common vetch（Vicia sativa）.This pathogen can seriously affect the yield and qualtity of common vetch.There is no systematic research on pathogen biology and prevention of anthracnose.The pathogen biology,occurence and chemical control of common vetch anthracnose were studied in this study in order to provide the technical support for the cultivation of common vetch（cv.Lanjian No.2）in areas of high elevation.This study mainly results were as follows:1.The pathogen of anthracnose in common vetch and its infectivity to some pastures were clarified in this study.From 2018 to 2019,the incidence of anthracnose of common vetch was 19.0%56.3%in Xiahe county,Gansu province.We combined morphology and multiple gene phylogenetic analysis based on gene sequences of an internal transcribed spacer（ITS）region and actin（ACT）,chitin synthase 1（CHS1）and glyceraldehyde-3-phosphate dehydrogenase（GAPDH）to identify anthracnose pathogen isolated from leaves and stems of vetch plants（cv.Lanjian No.2）.It was confirmed that the pathogen of strains were Colletotrichum spinaciae.This is the first report of C.spinaciae on common vetch and anthracnose caused by C.spinaciae is a new disease in China.Colletotrichum spinaciae exhibiting high pathogenicity to Onobrychis viciifolia and Avena sativa,and moderate pathogenicity to three“Lanjian”common vetch cultivars and 333/A,and low pathogenicity to Medicago sativa and Trifolium repens.However,Colletotrichum spinaciae has no pathogenicity to Lolium multiflorum.2.The study did indentify the pathogen culture characteristics.The mycelia of C.spinaciae could grow at pH values of 4-11 and 4 to 30℃.The optimum growth pH and temperature was 4 and 25℃,respectively.Peptone and yeast extract was conducive to the growth of mycelium.Mannitol was conducive to the growth of mycelium while lactose was not.The corn meal agar and spinach dextrose agar were the suitable medium for the pathogen growth.3.The present study demonstrated that anthracnose could affect the diversity of rhizosphere microbial communities in common vetch.Lower fungal diversity was observed in rhizosphere soils of diseased plants via high-throughput sequencing.Variations in relative abundance were observed in the fungal phyla Mortierellomycota and Glomeromycota and in the bacterial phyla Acidobacteria and Proteobacteria.The bacterial community in the rhizosphere soil of diseased plant was involved in the synthesis of amino acids（glycine,serine,threonine,alanine,aspartate and glutamate）,while the bacterial community in the rhizosphere of healthy plants was not.The analysis of the relationship among the rhizosphere soil microbes and soil properties showed that Colletotrichum was negatively correlated with soil available potassium（AK）and the content of soil organic matter（SOC）,and it was positively correlated with soil pH.Bacillus showed a negative correlation with soil pH and a positive correlation with AK and SOC content.4.Colletotrichum spinaciae can be effectively inhibited by the fungicide and the occurence of disease and thereby losses can be reduced in filed.Laboratory toxicity showed that the toxicity of 5 fungicides to C.spinaciae was difenoconazole-azoxystrobin 32.5%>pyrazoxystrobin 25%>carbendazim 50%>mancozeb 80%>Chlorothalonil 75%.The toxicity of difenoconazole-azoxystrobin32.5%was the highest,EC500 was 11.2717 mg·L-1.The results in pot experiments showed that pyrazoxystrobin 25%and carbendazim 50%mixtures had additive effect among three kinds mixtures.The field control efficacy of pyrazoxystrobin 25%difenoconazole-azoxystrobin 32.5%and carbendazim 50%were 68.88%,63.50%and20.62%,and the yields of common vetch and seed were increased by 21.6%,25.8%and 15.9%;32.5%,25.9%and 17.2%,respectively.Considering factors of control effects and yield,pyrazoxystrobin 25%,difenoconazole-azoxystrobin 32.5%,pyrazoxystrobin 25%and carbendazim 50%compound were effective fungicides to common vetch anthracnose caused by C.spinaciae. |
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