The Occurrence Dynamics And Pathogen Identification Of Hawthorn Leaf Spot And Field Screening Of Fungicides

Hawthorn is one of the fruit trees with high economic value in Rosaceae.In order to regulate the development of hawthorn leaf spot more effectively,the experiment firstly conducted a resistance survey of hawthorn leaf spot,and through the survey results to grasp the occurrence dynamics of leaf spot.Secondly,the pathogens fungus of leaf spot the hybrid combination of hawthorn Ruifeng×Xinbinruanzi were separated.The method of combining traditional morphology and molecular biology,to determine the taxonomic position of pathogens fungus.Finally,the field pesticide control research about hawthorn leaf spot,used mycelia growth inhibition,screening the prevention and cure effects of different concentrations of each agent.the main results are as follows:(1)The results of hawthorn leaf spot showed that the deciduous dynamics of susceptible plants were related to the increase of disease spots,However,infected plant have different tree vigour,lead to the time of the fall leaves is different.It takes about 20 days for the infected plants of the hawthorn hybrid progeny Ruifeng×Xinbinruanzi to appear from the spot leaves to the fall leaves.(2)Tissue separation of diseased plant leaves of Ruifeng×Xinbinruaniz of Hawthorn hybrid combination obtain pathogenic fungal from diseased parts of hawthorn leaves,after separation and purification,observations and DNA sequence alignments such as the Koch’s Rule regression test,morphological characteristics,preliminary determination of the causative agent of hawthorn leaf spot is Phoma macrostoma.(3)The dilution ratio of each agent of 50 % carbendazim WP,70%Thiophanate methyl WP,and 80 % Mancozeb WP is 500 x,800x,and 1000 x respectively,and the hawthorn hybrid combination inoculated with SI strain No.21(Ruifeng×Xinbinruanzi)×Xinbinruanzi and hawthorn hybrid combination Ruifeng×Xinbinruanzi of the susceptible plants in the field of hawthorn leaf spot disease test results showed: the control effect of 70 %Thiophanate methyl WP 500 xtimes solution is the best,49.12 %.the 80% Mancozeb WP 1000 x times solution is the worst,18.75 %,The other concentrations of these three agents have a certain control effect on hawthorn leaf spot.