Study On Occurrence Regularity And Green Control Technology Of Kiwifruit Black Spot Disease

Kiwifruit black Spot disease is a serious disease occurring in kiwifruit varieties（cuixiang and Xuxiang）in the main kiwifruit producing areas of Shaanxi Province in recent years.The occurrence of this disease seriously affects the fruit yield,quality,commodity and economic benefits,resulting in huge losses to kiwifruit production.Seriously hindered the sustainable,stable and healthy development of the industry,has become problem that desperately needs to be solved to be solved in kiwifruit production.At present,the etiology of this disease is still controversial,and its occurrence law and systematic prevention and control techniques have not been reported.Therefore,it is particularly important to explore and understand the etiology,incidence and prevention and control techniques of this disease.This research take the field investigation,sampling analysis,pathogen isolation and identification,biological characteristics,combining with indoor toxicity measurement and field experiment,to preliminarily explore kiwifruit black spot disease pathogen identification,biological characteristics and occurrence law and control technology in the field,and clarify its etiology,pathogenesis regularity and provide scientific basis and reference for this disease prevention and control.In order to study and form a set of preliminary,systematic and scientific prevention and control system.It provides scientific basis for the prevention and control of the disease.The main results of this study are as follows:1.The pathogen and biological characteristics of kiwifruit black spot disease were determined.The disease fruit of"Cuixiang"kiwifruit with black spot disease was collected from four towns in Zhouzhi County,Shaanxi Province.The pathogen was identified as Diaporthe phaseolorum by pathogen isolation,pathogenicity detection,morphological analysis and multi-gene phylogenetic analysis.The optimum growth medium was PDA,p H6～8,carbon source was mannitol and sorbitol,nitrogen source was peptone,and temperature was 28℃.The culture condition of total darkness was more suitable for mycelium growth.2.The field fluctuation and incidence of the disease were clarified.Through 2019 to the end of August 2021 at the peak of the incidence of kiwifruit in Zhouzhi county and Meixian county by random sampling method and regular,fixed site,fixed garden disease growth and decline of dynamic investigation and different nutrition fertilization experiment.The results showed that the onset of the disease was in early July,and the peak was in late July and mid-August.It was mainly found in"Cuixiang"and"Xuxiang"varieties,and the disease index and fruit rate of the former were much higher than that of the latter.Shu Ling Shu big,light transmittance shu low incidence;The incidence rate of nitrogen fertilizer was higher than that of calcium and potassium fertilizer.Kiwifruit variety,tree age,field light transmittance and nutrient fertilization management were the important factors affecting the severity of disease.3.The influence of meteorological factors on the occurrence of disease was explored,and a disease prediction model was established for meteorological factors,fruit rate and index.The meteorological data from June to August of 2017 to 2020 and the fruit rate and index of each year field survey were used for linear regression analysis and meteorological model,and the regression equation was tested with the data in 2021.The results showed that the occurrence and prevalence of kiwifruit black spot disease was negatively correlated with total rainfall and days of rainfall,and positively correlated with sunshine duration and average daily temperature.The disease meteorological model was Y₁=1.379X₁-0.246X₂-26.249,Y₂=4.007X₃-83.802[disease index（Y₁）,disease fruit rate（Y₂）,Average mean air temperature from early June to late August（X₁）,rainfall days from early August to mid-August（X₂）,average air temperature from early July to early August（X₃）].The data of 2021 were used to verify that the fitting accuracy of disease index was 97.93%,and the fitting accuracy of disease fruit rate was 94.33%.The results showed that high temperature and little rainfall were beneficial to the disease prevalence.4.Four green control agents,80%allicin EC,0.3%matrine EC,5%amino-oligosaccharide AS and 0.5%carvaterol SL,were screened out.Their EC₅₀ values ranged from 2.07μg·m L^-1to 118.49μg·m L^-1,and their field control efficiency was above60%.The best period of prevention and treatment was from early July to late July.