Survey And Control Technology Research On Leaf Disease Of Photinia×Fraseri In Zhenjiang Region, Jiangsu Province

With the purpose to control the leaf spot diseases of photinia×fraseri, the author has firstconducted a survey of the morbidity of leaf disease of photinia×fraseri in Zhenjiang region, andthen made experiments on the pathogen and the chemical and biological control of the maindisease. The chief results are shown as follows:1. According to the findings of the survey, five main symptoms of leaf disease of photinia×fraseri have been detected in Zhenjiang region, among which Symptom V is the severest diseaseand has the highest occurrence rate. The occurrence of this kind of disease is closely related toseedling age and the site conditions of soil and slope.2. By Koch's postulates, Fungus II has been identified as the pathogen of Symptom V, andby morphological observation and molecular identification, it is defined as Pestalotiopsismicrospora. This is a first report in China that Fungus II has caused leaf spot disease in photiniafraseri.3. An indoor chemical agents screening and field control effect experiment has beenconducted of Pestalotiopsis microspora of photinia×fraseri. The inhibitory experiment ofmycelium reveals that, of the ten supplied fungicides, the antifungal effect increases successivelyamong Azoxystrobin250g/L Suspension Concentrate, Mancozeb80%wettable powder and25%Prochloraz Emulsion in water, with their EC50values being4.4997μg/mL,4.6283μg/mL, and4.8677μg/mL respectively. Through the experiment on the efficacy of three kinds of chemicals atfour levels of pesticide concentration in field practical prevention, it is demonstrated that, at theconcentration of500times, the prevention effect of25%Prochloraz Emulsion in water orAzoxystrobin is better, both reaching more than60%. They thus can be used for field control.Among them,25%Prochloraz achieves the best control effect (75.62%). In contrast, the controleffect of Mancozeb80%is relatively poor, being only58.46%at the concentration of500times.Synthesizing the experiments of both indoor and field preventions, the author contends that25%Prochloraz is the best control fungicide for the leaf disease of photinia×fraseri.4. The indoor biotech control experiment of Pestalotiopsis microspora of photinia×fraseriand agar plates test demonstrate that, among the11strains of bacteria kept in the BiotechDevelopment Center of Jiangsu Polytechnic College of Agriculture and Forestry, NL4, NL5andNL6have better antagonistic effect on Pestalotiopsis microspora and they are identified throughmorphology and molecular identification respectively as belonging to Paenibacillus polymyxa,Bacillus subtllis and Bacillus amyloliquefaciens. Among them, the antagonistic effect of Bacillusamyloliquefaciens ranks the highest, with its anti-bacteria effect reaching60%, while the antagonistic effects of Bacillus subtllis and Paenibacillus polymyxa rank next, with theiranti-bacteria effects being44.43%and37.73%respectively.