| Typical spike-stalk disease samples were collected from Hami,Turpan,Shanshan,Wujiaqu,Changji,Shihezi,Bole,Yili and Aksu regions of Xinjiang.After isolation,cultivation and punfication obtained 141 strains,depended on the colony characteristics.These strains are considered to belong to the members of the microspore group in Alternaria sp.According to their colony characteristics,conidia,conidiophores and mode of production,initially defined the two kinds of pathogen Alternaria sp.The representative strains were selected for pathogenicity test.The results showed that the symptoms of the two strains were consistent with the natural symptoms in the field,and the original strains were isolated from the inoculated strain.Using fungal rDNA-ITS universal primers(ITS1 / ITS4)and histone 3gene primers(H3-1a / H3--1b)were used for PCR amplification and sequencing.Put the results of sequences to Genbank for comparison analysis and phylogenetic tree,further validate the resluts of the morphological identification.Grape Alternaria rot pathogens were identified as Alternaria tenuissima and Alternaria alternata.This result with the past that grape Alternaria rot caused by Alternaria viticola are significantly different.The biological characteristics of two species of pathogenic bacteria were determined.The results showed that two species of pathogenic bacteria has a wide range of temperature adaptation,5? ~ 35? mycelium can grow,the optimum temperature for the mycelium growth and spore germination was 25?,higher than 35? or less than 5? are not conducive to pathogen the mycelial growth and spore germination;growth of humidity requirements are not strict,in 25%~100% relative humidity can grow well,but the conidia germination need higher humidity,the relative humidity of 90%~100% was the best,the spore germination rate can reach more than 60%,while the relative humidity is reduced to 75%,the spore germination rate is reduced to about 30%,the relative humidity is reduced to 50%,while only about 15% of the spores can germinate,so appropriate humidity range the disease should be more than 75%,before and after flowering once when the rainy weather,the disease often pandemic.The light conditions of the two pathogens disseminated disease had no significant effect,but UV inhibiting effect on two kinds of bacteria,UV irradiation time is longer,the more obvious inhibition.Experiments show that two kinds of pathogenic bacteria can directly invade grape spike stalk tissues,but the incidence of wound infection is faster than direct invasion.Temperature of the incubation period of the disease is greatly affected,when the temperature is 25 ?,the incubation period of 8 days;when the temperature is 5 ?,two kinds of pathogens of grape spike stalk incubation period of up to 15 days.Too low temperature is also harmful to the infection of pathogens.The fungicides screening of 15 kinds of commonly used fungicides,and the preventive and protective effects of these agents in vitro inoculation experiments to identify virulence of these agents on two kinds of Alternaria are basically the same.After a comprehensive assessment of the 70% thiophanate methyl,80% mouldy zinc,better control effect of 50%tebuconazole on grape Alternaria rot,and the control effect is relatively stable.During the critical period of disease occurrence,the two control of inflorescence separation period and the last 1 weeks after flowering could achieve good control effect;while the previously reported good prevention effect of 75% chlorothalonil and 80% bacteria the spirit of the two pathogens inhibitory effects are poor,not suitable for use as the main control in field. |
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