The Epidemic Regularity Of Heracleum Moellendorffii Hance Powdery Mildew And Studies Of Its Control Measures

As a food and medicine wild vegetable,H.moellendorffii Hance which stems and leaves taste delicious,containing richly multiple nutrients such as vitamin,protein and amino acids,is one of the common wild vegetable in forest areas of Heilongjiang province.At present,H.moellendorffii Hance faces a series of problems including few wild resources,difficult harvest,the growing environment destroying,etc,and can not meet market requirement.Consequently,it is vital to conduct artificial cultivation of H.moellendorffii Hance.In recent years,the disease of H.moellendorffii Hance powdery mildew occurs severely,reducing the yield and qualities of plant,affecting the scale production at the artificial cultivation.The researc h investigated occurrence dynamics of H.moellendorffii Hance powdery mildew in the open field,studying effects of cultivation measures on the powdery mildew occurrence and plant growth that can help to understand the occurrence dynamics of the powdery mildew and cultivation measures controlling the occurrence of the powdery mildew effectively,which can provide guidance for controlling the occurrence and epidemics of the powdery mildew.The research results are as following:(1)The morphological characteristics of H.moellendorffii Hance powdery mildew was observed using the light microscopy(LM)and scanning election microscopy(SEM),and the ITS and 28 S codes were amplified and sequenced,conducting the phylogenetic trees.Based on the morphological characteristics and molecular analysis,the fungus on H.moellendorffii Hance was identified as E.heraclei.(2)Indoor environment test showed that temperature(20 ℃～25℃)and humidity(60%～80%)were beneficial to the infection of H.moellendorffii Hance powdery mildew.In the open field,temporal dynamics of H.moellendorffii Hance powdery mildew were divided into three stages.The initial infection and exponential growth period were from early Jun to early Jul,lasting about 20-30 d.The disease peak period was from the beginning of Jul to the beginning of Aug,lasting about 30 d,and from the middle of Aug,the disease increased slowly.In the spatial prevalence of powdery mildew,the primary spread area of disease was irregular,and the disease was more serious,spreading more distance on the northeast and south direction.The maximum spread distance was 3.12 m.The whole investigation period of powdery mildew,the disease was more serious,spreading more distance on the northeast,and the maximum spread distance was 6 0.2m.The host growth and development stage and climatic factors including temperature,humidity,precipitation,wind direction and speed influence the disease epidemic dynamics greatly.(3)The interaction of higher soil moisture content(60%～80%)and organic matter content(75g～100g/kg)can control the occurrence of powdery mildew,and the disease incidence and index were lower obviously compared with other interactive treatments.Under the above treatment,leaf expansion,natural growth height,maximum leaf areas and yield per plant were higher than other interactive treatments,accompanying with higher contents of soluble sugar,soluble protein,vitamin C and coumarin compared with other interactive treatments obviously.(4)In the open field,the planting density(plant and row spacing 40cm×60cm)can inhibit the epidemics of powdery mildew obviously.Compared with the high planting density(plant and row spacing 20cm×60cm and 30cm×60cm),under the planting density(plant and row spacing 40cm×60cm),the disease incidence and index were lower,accompanying with higher temperature and humidity,stronger light of plant canopy,and better ventilation that can in favour of controlling the epidemic of powdery mildew.In addition,the planting density(plant and row spacing 40 cm ×60cm)can benefit the plant growth and nutrient content accumulation of vitamin C and coumarin,etc.(5)Intercropping maize perfected the canopy micro-environment of H.moellendorffii Hance effectively,and improved phenolic content,protective enzyme activities and plant resistance,controlling the occurrence and epidemic of H.moellendorffii Hance powdery mildew effectively.Under the intercropping model(6:1),the disease occurre d lightly,accompanying with stronger growth,highest yield of plant and higher nutrient content of vitamin C and coumarin,etc.(6)Thiophanate-Methylate(1500mg/L)and Pyraclostrobin(1500mg/L)can inhibit the conidial germination,conidiophores formation and mycelial growth.Further field test showed that 1500mg/L concentration of Thiophanate-Methylate and Pyraclostrobin can control the occurrence and epidemic of H.moellendorffii Hance powdery mildew,and the relative control effect reached 69.81% and 58.89%,with higher activities of POD,SOD,CAT and PAL compared with control treatment.