| Jujube black spot was a new disease in Xinjiang Province in recent years. The typical symptom was that blackish-red spots occurred on the top or shoulder of jujube fruits, with time, the edge was much clear, the sarcocarp changed into pink and blacken at last, the part of disease which changed into harden at last is easy separation. It affected the economic value that the fruit was bitter and inedible. This experiment ascertained the pathogens by Koch's Rule, identified the pathogens by observed morphological feature and combined molecular biological technique. Meanwhile, study on infection cycle of pathogen, analyze on the relevant factors of disease occurrence, investigation of jujube black spot on different jujube varieties in the field, and finally, screening the efficienf agents in field. The main results are as follows:(1) The pathogen was identified by Koch's postulates. The experiments found that determine the pathogenic fungi were Alternaria alternate(Fr.:Fr.) Keissler, by morphological observation, pathology inoculation test and the combination of ITS and RPB2 gene fragments combined phylogenetic analysis.(2) The continuous separation has been done from different organization on jujube and the soil under canopy by jujube in Hetian and Aksu regions in November 2013 to April 2014. The result show the trunk bark and fallen leaves were main wintering site by conidium.(3) In 2012 a to 2014 a, the survey found that the pathogens on the trunk bark all the year. The pathogens started to infect the shoots and leaves in the first ten days of June. Flowers were infected in the middle ten days of May. Fruits were infected in the last ten days of June. The pathogen isolation rate of jujube fruits was correlates positively with temperature and humidity.(4) The isolation rate of pathogen showed correlated significantly in fruits when temperature was 25~28?, humidity >70% for two weeks.(5) In addition, relevant factor on the occurrence of jujube black spot: the disease incidence of ‘Junzao'(32.79%) and ‘Hupingzao'(30.73%) were heavier, ‘Huizao'(4.37%) was lighter. Disease incidence in 3 a jujube orchard was 3.01%. Incidence was positively related with age in 5 ~ 12 a. There was a higher incidence of disease in jujube orchard with intercropping. Basically the same disease epidemic situation in jujube orchard which refine management(30.57%) significantly lower than the extensive management(43.49%). flood irrigation(37.18%) was significantly higher than drip irrigation(26.62%)Incidence of loam(32.71%) was significantly higher than sand soil(21.68%). The severity of the disease occurred differently in directions: south > west > east > north.(6) In this study, it surveyed the occurrence statu of the disease of 13 jujube varieties. Filed survey results showed that: The occurrence of disease of ‘Junzao' and ‘Hupingzao' were the most severe, and the incidence of more than 30%; the disease did not occurred on ‘Yuancui'?‘Mayazao' and ‘Suanzao'. Using preferred fungus dish as inculum to determination the pathogenicity on isolation jujube, the results showed that: The pathogenicities of pathogen of ‘Junzao' and ‘Hupingzao' were the strongest, and the disease index ?40; the pathogenicities of ‘Huizao'? ‘Dongzao' ?‘Zanhuangzao' and ‘Mayazao' were the weakest, and the disease index =20; Relative to the leaves, the pathogenicities of pathogen of ‘Junzao'? ‘Huizao'? ‘Zanhuangzao' were the strongest, and the weakest was ‘Dongzao'? ‘Mayazao' and Wild jujube.(7) At the same time, conducted field control experiment with 7 kinds fungicide by randomized block. The control efficacy of 60% pyraclostrobin · metiram(5% pyraclostrobin · 55% metiram) WG applied at 1500 times and 3000 times against jujube black spot in the filed was 90.25% and 82.7%; The control efficacy of 3% polyoxin WP applied at 200 times against jujube black spot in the filed was 90.25%. |
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