Pathogen Identification And Screening Of Control Pesticides For Fruit Anthracnose Of Zanthoxylum Bungeanum

Prickly ash is an important rural economic tree species in our country.The occurrence of prickly ash anthrax seriously affects the production and quality of prickly ash.Clear pathogen is the premise of effective control of disease.At present,although there have been reports on the pathogenic bacteria of zanthoxylum anthracnose,although these studies reported that zanthoxylum anthracis was anthracis collosporum,however,the identification method of zanthoxylum anthracis has not been systematically reported.Therefore,this study planned to use tissue separation method,Koch’s rule verification,morphological characteristics and molecular biology techniques to systematically identify zanthoxylum anthracis.On this basis,biological characteristics of zanthoxylum anthracis were further studied,indoor virulence activities of different fungicides against zanthoxylum anthracis were detected,and field control experiments of fungicides were carried out.The following research results were obtained:（1）The field incidence regularity of anthracnose of prickly ash fruit in Yangling comprehensive experimental demonstration station was investigated.It was found that the fruit of Fengxian Dahongpao and Hancheng Dahongpao were infected with anthracnose.The onset time of anthracnose of prickly ash fruit was earlier than that of prickly ash,and the harm of anthracnose on prickly ash fruit was more serious than that of prickly ash.The symptoms of chicken peppers started around early June,while those of Korean peppers started around mid-June.Phoenix pepper anthrax disease index appeared rapid growth period in June 20,at this time the disease index is about 0.94,after that the disease index rose rapidly.The period of rapid growth of the disease index on the Korean pepper was around June 27,when the disease index was about 1.4,and then the disease index rose rapidly.（2）In this experiment,the pathogens of zanthoxylum fructus fruit with obvious symptoms of anthrax were isolated,and the main pathogen of zanthoxylum fruit anthrax was Colletotrichum fructicola by morphological analysis,pathogenicity detection and molecular biology identification.Colletotrichum fructicola was first reported to cause anthracnose of prickly ash fruits.（3）Under indoor conditions,the mycelium of pathogenic bacteria of zanthoxylum anthracnose can grow on 7 kinds of medium,and the growth rate is the fastest on PDA and carrot medium,and the most suitable sporulation medium is PDA and Chazi medium.25℃was the optimal temperature for mycelia of pathogenic bacteria,and 30℃is the best temperature for sporulation of fruiting anthrax.p H 9 is the optimal p H for pathogenic bacteria.Under this condition,mycelium growth rate is the fastest and sporulation quantity is the largest.The pathogens could grow and produce spores under the six carbon sources,among which,starch was the largest colony diameter,and starch and glucose were the most suitable carbon sources for sporulation.Beef extract and peptone were the most suitable for mycelia growth.Different nitrogen sources had little effect on mycelia growth,but there was a great difference in mycelia production.Beef extract treatment had the largest sporulation.（4）Laboratory biotest showed that phenylene methyclozole,hexazolol,pyrazole methyloxide,imidylamine and other agents had obvious bacteriostatic effect on pathogenic bacteria mycelia of prickly ash anthracnose,and their EC₅₀ values were0.719,0.743,2.000,0.026,0.763 mg·m L^-1,among which imidylamine had the strongest inhibition effect on pathogenic bacteria mycelia.The EC₅₀ value was only0.026 mg·m L^-1.Chlorothalonil,mancozeb,flurimide and pyrimethanil had inhibitory effects on the growth of pathogenic bacteria,and their EC₅₀ values were 29.185,29.900,49.500 and 63.300 mg·m L^-1,respectively.The inhibitory effects of primathromycin,dinacylamine,mefrol,matrine emulsion,emodin methyl ether and gosseed on the mycelium of fructus anthracis were weak,and their EC₅₀ values were 133.800,143.551,208.400,567.677,117.100,241.306 mg·m L^-1,respectively.The field efficacy test showed that 450 g/l imidazole water emulsion 1000-2000 times and 30%hexazolol suspension 10-12 ml/mu treatment had better control effect on zanthoxylum anthracnose.After the third spraying,the control effect reached 82.06%and 73.97%,respectively,indicating that imidazole and hexazolol had good control effect on zanthoxylum anthracnose.In summary,field investigation of anthracnose of prickly ash was conducted in this study.The results of morphological observation and polygenetic phylogenetic identification showed that anthracnose of prickly ash was the pathogen of fruit anthrax.The biological characteristics of fructus anthracis were clarified,and the agents for controlling anthracnose of fructus anthracis were screened,which laid the theoretical foundation for the comprehensive control of anthracnose of fructus anthracis.