Study On Identification And Biological Characteristics Of The Pathogen Of Carya Illinoinensis Anthracnose

Carya illinoinensis is one of important oil-producing nut trees in the world.The fruit has a higher economic value.In recent decades,it has become a widely cultivated,high-quality economic forest tree species and greening tree species in China.Many countries have large areas of introduced cultivation.In recent years,with the continuous expansion of planting area and the arrival of the fruiting period,pests and diseases have gradually increased,which hinders the growth of production and seriously affects the development of the whole industry.Anthracnose disease of C.illinoinensis is very serious in various regions of Anhui Province.In severe cases,the fruit falling rate was up to 70%,which caused huge economic losses.In this study,the pathogen of the anthracnose disease of C.illinoinensis is isolated and identified in Guanting Town,Hefei City.Meanwhile the biological characteristics is analyzed and the pathogen’s sensitivity to different fungicides is also determined.The main research results are as follows:1.Isolation,identification,and pathogenicity testing of the pathogenThe pathogen was isolated and cultured using the tissue isolation method,and a pure strain was obtained after several rounds of purification.The genomic DNA of the strain was extracted,and the ITS,ACT,as well as GAPDH fragments were amplified to construct multigene phylogenetic tree.Based on morphological characteristics and multigene phylogenetic anslyses,the pathogen was identified.According to Koch’s rule,Colletotrichum fructicola was identified as the pathogen causing anthracnose disease of C.illinoinensis.2.Study on biological characteristics of the pathogenThe effects of different culture media,temperature,p H values,carbon sources,nitrogen sources,and light on mycelial growth are studied.The results show that the optimal temperature for the strain is between 25-30℃.The strain grows best on OA and SNA culture media.Extremely acidic or alkaline environments are not suitable for the growth of the strain.The strain grows fastest at a p H value around seven.When maltose and sucrose were used as carbon sources,the strain grows faster.The strain has a high utilization rate of peptone and yeast extract,and grows well when these are used as nitrogen sources.Compared to light exposure and natural scattered light,the strain grows faster in a completely dark environment.3.Determination sensitivity of the pathogen to different fungicidesThrough using the mycelial growth rate method,the inhibitory effects of thirteen fungicides on mycelial growth are determined.The study shows that thirteen kinds of fungicides have different degrees of inhibition on the pathogen.250 g/L prochloraz EW has the best antibacterial effect,with an EC₅₀value of 0.0458μg/m L,followed by 45%tebuconazole-prochloraz EW and 125 g/L epoxiconazole SC,with EC₅₀values of 0.0629μg/m L and 0.0919μg/m L,all of which are less than 0.1μg/m L.125 g/L Kresoxim-methyl SC and 40%chlorothalonil SC show the poorest inhibitory effects,with EC₅₀values of83.3034μg/mL and 97.5212μg/mL.