| Strawberry is an important economic crop in China and crown rot disease has seriously harmed the yield and quality of strawberry.This study is aimed to collect the strawberry crown rot disease samples in different areas of Zhejiang province to identify the pathogens,compare the Colletotrichum fungi from crown rot and leaf anthracnose,to study the influence of environmental factor on pathogen growth,spore production and pathogenic,and to develop the bio-chemial control of strawberry crown rot disease.The research achieved the following results:1.Isolation and identification of the pathogens of strawberry crown rot disease.Based on morphological characteristics and polygene molecular systematics analysis,287 strains of strawberry crown rot were isolated and identified into 12 species.Among them,Colletotrichum siamense,Fusarium oxysporum,Epicoccum sorghinum and Co.fructicola accounted for 63.07%,26.48%,2.09%and 1.39% of the total strains,respectively.The results of inoculation experiments showed that Co.siamense,F.oxysporum,Co.fructicola,F.equiseti,E.sorghinum and Curvularia trifolii all caused rot and blackening in the stem base of strawberry,which indicated that Co.siamense,F.oxysporum and F.equiseti were the most virulent pathogenic fungus.At the same time,the differences of different types of pathogens causing strawberry crown rot in strawberry varieties and regions were also identified.2.Comparative analysis of biology of strawberry Colletotrichum from different sources.The experimental results showed that the species from the stems and leaves of strawberries were the same,but there were differences in biological characteristics and pathogenic characteristics.The mycelial growth ability and spore germination rate of Co.siamense in the leaf part were significantly higher than those in the stem.There was no significant difference in the sporulation of all kinds of Co.siamense under shaking culture condition,and the sporulation amount of Co.siamense in the stem was the highest under natural conditions.Under the condition of injury,Colletotrichum from both sources could cause the disease in the leaves and stems of the four strawberry varieties,but the pathogenicity was different to some extent.The pathogenicity of stem Co.fructicola in leaves was the weakest,while the pathogenicity of stem Colletotrichum was higher than that of leaf Colletotrichum.Under the condition of no injury,the pathogenicity of various anthracnose fungus was relatively weak.Hongjia and Tianxianzui varieties are more susceptible to anthracnose disease.There were also some differences in the metabolic ability of different sources of Colletotrichum to utilize various growth substances such as carbon,nitrogen sources and phosphorus and sulfur Sources.Co.siamense can use nitrogen sources,nutrient supplement elements and pH fully,while Co.fructicola has the best metabolic ability to carbon sources,nitrogen sources and peptide nitrogen sources.3.Effects of environmental factors on growth,sporulation and pathogenicity of strawberry crown rot pathogens.It was found that the most suitable environmental conditions for growth and sporulation of different pathogens were different.The most suitable temperature for mycelial growth and sporulation of pathogenic fungus is 25-30℃,pH is between 5-7,and the optimal light conditions are also different.The results showed that the pathogens were more active under high temperature and neutral or acidic conditions.At the same time,the pathogenicity of the pathogen was also significantly different under different temperature and humidity conditions.The higher the temperature and humidity,the stronger the pathogenicity of the strains.Most of the pathogens had the highest pathogenicity at the temperature of 25℃/ humidity 95% and the temperature of 30℃/ humidity 95%.4.Biochemical cooperative control technology for strawberry crown rot disease.It was found that fluazinam and Bacillus amyloliticus had the strongest fungophilic effect on strawberry crown rot from 7kinds of chemical reagents and 5 kinds of biological agents screening reagents with better effect.Biocompatibility analysis showed that fluazinam had good compatibility with Bacillus amyloliticus,and the two could be mixed.When the two were mixed at the volume ratio of 3:7,the compound had obvious synergistic effect on the inhibition of strawberry crown rot pathogens,the highest toxicity ratio could reach 1.35,and the field control effect was also significantly improved.E.sorghinum,S.lycopersici,P.herbarum,and Cu.trifolii were found to be capable of causing crown rot in strawberry for the first time,and there were differences in biological characteristics and pathogenicity between the Colletotrichum strains that cause crown rot and leaf anthracnose.Under the condition of high temperature and humidity,pathogenic fungus are more likely to grow sporulation and develop disease.At the same time,the combination of fluazinam and Bacillus amyloliticus at the ratio of3:7 had obvious synergistic effect on the control of strawberry crown rot disease. |
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