The Occurrence Characteristics And The Species Of Parasitism Fungi Of Pathogenic Of Powdery Mildew Of Mulberry In Nanning

Powdery mildew of mulberry is one of the serious diseases in mulberry.The occurrence of disease causes mulberry leaf to be full of white powder,quality becomes inferior and affect the growth of mulberry tree badly,the silkworm eat the mildew leaf which was infect powdery mildew is weak and disease easily,the cocoon amount,cocoon layer amount and cocoon layer rate all reduces.According to the occurrence of powdery mildew of mulberry,this study carried out a field systematic investigation in the farm of Guangxi University in Nanning and site investigation in mulberry garden of the Sericulture Scientific Institute of Guangxi Zhuang Autonomous Region.Through the field survey results found that all the mulberry varieties have occurred mulberry powdery mildew on leaf back in all survey sites,the main blade on the back,the disease except in January and February,other time all have happened,disease index reached up to 80.94 in January,sick leaves rate reaches as high as 96.73%in late December,December producing black small particles cleistothecium namely,In January of the following year,the mulberry leaf shed and the disease ended;Combined with meteorological data analysis results show that the average temperature is higher than 27 0C go against to occurrence of mulberry powdery mildew on leaf back,the higher relative humidity the more go against to the occurrence of the disease;The mulberry mildew on leaf surface was only found on the Taiwan big fruit mulberry in Nanning,it mainly affected the leaf surface and produced conidia at the site of onset.December producing black small particles cleistothecium namely.Morphological and molecular biological identification showed that mulberry powdery mildew on leaf back was caused by Phyllactinia moricola and mulberry mildew on leaf surface was caused by Erysiphe mori.The mulberry leaves under the room temperature and 4 ? environment to simulation overwintering,using neutral red and methylene blue dye mixture,the results found that conidium and ascospore of mulberry powdery mildew on leaf back are successful overwintering in the different conditions;the mulberry leaves were placed in the field and buried under the field soil for 5cm in December,all the pathogenic bacteria had disappeared in march of the following year.The conidia germination inhibition test showed that among the four fungicides tested,Triadimefon had the highest inhibition rate of conidia germination(82.02%).Secondly,the inhibition rate of Carbendazim was 42.69%.The inhibition rate of Thiophanate-Methyl was 37.02%.However,Lime sulphur no inhibitory effect on the germination of conidia of mulberry powdery mildew.It was found that two kinds of fungi had heavy parasitism on the surface of the Cleistothecium of pathogenic bacteria of mulberry powdery mildew on leaf back.Through the observation of morphological characteristics and the ITS1/ITS4 sequence analysis,the two kinds of heavy parasitism fungi were identified as Cladosporium oxysporum and Lecanicillium psalliotae.