Study On Occurrence Regularity And Biological Control Of Rape Sclerotinia Stem Rot In Main Planting Areas Of Hunan Province

The study in Changde Anxiang, Changde Dingcheng, Yiyang Datonghu of Hunan province, through investigated the rape cultivation, Sclerotia germination time, amount of apothecium dynamics, occurrence degree of Sclerotinia sclerotiorum, goodness of fit to rape florescence and apothecium breaking, climatic conditions of2011year, analyzed the occurrence regularity of Sclerotinia sclerotiorum in main planting areas of Hunan province. Actinomycetes were isolated from soil samples in the Jiuzhaigou National Nature Reserve, which screened antagonistic activity of strains on Sclerotinia sclerotiorum.It provided materials for the developed bio-control Sclerotinia sclerotiorum.The main results are as follows:1The occurrence of Sclerotinia sclerotiorum in Hunan province in2011.In Changde, the Sclerotinia sclerotiorum incidence rates of leaf, stem were respectively8.5%,0.8%, the disease index was0.27in the rape florescence (March21). The disease hazard the blade was higher in final flowering (April18). Leaf incidence rate was50.7%, the stem of diseased plants was6.3%and the disease index was2.93. The stems of diseased plants rate was13.6%and the disease index was6.8in maturity (May3), which impacted seriously on the local yield. The rate of diseased plants was14.3%in Dry fields (the perennial cotton-oilseed rape ground), slightly higher than the rate12.6%in paddy field (perennial rice-oilseed rape or rice-rice-oilseed rape for land). The disease index was6.7in Dry fields, and6.8in paddy fields.Sclerotinia sclerotiorum was epidemical on rape florescence in main growing areas Yiyang. Leaves of diseased plants rate of Brassia campestris was14%, and some infected stem appeared, florescence stage to the flowering ending (the stage of petals wither) was infection phase, the incidence rates of leaves and stem of Brassica campestris were up to52%and10.75%respectively. The stem incidence rate was aggravated in late mature stage, which caused serious loss of rape yield.2The screening and application of the antagonistic strains on Sclerotinia sclerotiorum.137Actinomycete strains were isolated from the Jiuzhaigou National Nature Reserve soil samples, after the growth confrontation test and culture filtrate inhibition test, we got two strains, JZG001and JZG117,which showed high inhibition activity on Sclerotinia sclerotiorum with mycelium growth reduction over70%. Using the16S rDNA gene universal primer18#,19#for PCR, the results of BLAST on NCBI showed that JZG001and JZG117shared99%nucleotide identities with some Species of Streptomyces. According to physiological, Biochemical, morphological characteristics, JZG001and JZG117were identified to be Streptomyces microflavus and Streptomyces flaveus. The control efficiency of JZG117on Sclerotinia sclerotiorum was53.6%in field trial...