Investigation On The Occurrence Of Blossom Blight Of Kiwifruit And Screening Of Fungicides

Blossom blight of kiwifruit is a common bacterial disease currently in pruduction,and has become another serious disease after the kiwifruit bacterial ulcer disease in Yongzhou,Hunan province.in order to determine the pathogen of blossom blight of kiwifruit,and screen more effective prevention and control fungicides and combination to provide scientific guidance for agricultural production.this study investigated the occcurrence of blossom blight of Miliang-1 and Hongyang in representative kiwifruit producing areas such as southern Hunan、eastern Hunan and northwestern Hunan,and summarized its regularity.at the same time,the isolation and identification of pathogens、indoor antibacterial test of fungicides、antibacterial screening of traditional Chinese medicine extracts、synergistic bacteriostasis of compounds、the field prevention and control test of agents and other aspects were carried out.the research results are as follows:（1）Investigation on the orrurrence of blossom blight.the average incidence of blossom blight in Hongyang kiwi was 53%,while the average incidence rate of flowers was 23.9%,and the average disease index was 15.1.The most serious in these areas are Yun Tian town of Zhuzhou、Heping town of Jiang Hua county and Niuren village,Ma Chong Township,Fenghuang County,The disease index is 31.1、27.4、23.2 respectively.The incidence of"milliang-1"in the Fenghuang area is relatively mild,the average incidence rate was 15.9%,while the average disease incidence rate of flower was 10%and disease index was 5.1.the overall incidence rate was significantly lighter than that of the same area."Hongyang kiwifruit"also found that the occurrence of blossom blight increased with the increase of altitude and tree age.The overall disease rate of the survey reached 100%.（2）Isolation and identification of pathogen of blossom blight.the strains was isolated from the diseased flower buds of kiwifruit,Through Koch’s rule,combined with the morphological observation and molecular identification of the pathogen,the pathogen of blossom blight in Yongzhou,Hunan province was Pseudomonas viridiflava.（3）Indoor bacteriostatic test of fungicides and extracts of Chinese herbal medicine.in the indoor bacteriostatic test of Pseudomonas viridiflava,the best bacteriostatic effect is 3%zhongshenmycin,with EC₅₀value of 0.71mg/ml,followed by 50%chlorobromoisocyanuric acid and 3%benziothiazolinone,with EC₅₀values of4.21mg/ml and 10.50mg/ml respectively:In the indoor bacteriostatic test of Pseudomonas syringae,the best bacteriostatic effect is 3%zhongshenmycin,with EC₅₀value of 0.028mg/ml,followed by 5 billion cfu/g multiplatoma and 50%chlorobromoisocyanuric acid,with EC₅₀values of 0.57mg/ml and 3.95mg/ml.taking the pathogen（Pseudomonas viridiflava）of blossom blight of kiwifruit as the tested strain,at the concentration of 500mg/ml,the antibacterial effect of Acorus tatarinowii,Rheum palmatum,Gleditsia sinensis and Paeonia suffruticosa were the best in the antibacterial screening test of single traditional Chinese medicine extract,with the diameter of bacteriostatic circle is 12.51mm,10.22mm,8.39mm and8.19mm respectively.the best formula of four traditional Chinese medicine:A Acorus tatarinowii 347.13,B Rheum palmatum 481.24,C Gleditsia sinensis 431.83,D Paeonia suffruticosa 538.28.（4）Field prevention and control test of the agent.through the combination of spray and root irrigation.the best control effect was 14（thiodiazole copper+synergistic spirit,thiodiazole copper+synergistic spirit,thiodiazole copper+synergistic spirit）,15（thiodiazole copper,benziothiazolinone+chlorobromoisocynuric acid,spring thunder.benziothiazolinone+chlorobromoisocyanuric acid）and 5（benziothiazolinone,benziothiazolinone,benziothiazolinone）.the control effects of these treatment groups on diseases reached 73.49%,70.73%,68.79%.