Analysis on Occurrence and Damage of Wheat Sheath Blight

Wheat sheath blight is a soil-borne fungal disease with common occurrence and serious damage in wheat.The disease has wide host range,which can infect the gramineous crops such as wheat,barley,oats,maize,sorghum,millet and rice,as well as cotton,flax,tobacco,potato,soybean,peanut,sugar beet and cabbage.It is mainly occurred in the leaf sheath and stem of wheat.When the wheat seedlings are emerged,the rhizome and leaf sheath can be damaged,and the root can also be infected.Wheat sheath blight is almost throughout the wheat planting area in various temperate zones around the world,which seriously affects the high yield and stable yield of wheat,and causes great economic losses.Currently,the disease has different degrees of occurrence in wheat areas in nearly 20 provinces(cities) of China,and especially has most common occurrence in wheat area in the provinces of Jiangsu,Zhejiang,Anhui,Shandong,Henan,Hebei,Shaanxi,Guizhou,Hubei and Sichuan.It has posed direct threat on wheat yield and quality,the yield loss is about 5%-10% under light condition,which is up to 20%-40% under severe condition.The perfect stage of the pathogen causing wheat sheath blight isCeratobasidium graminearum(Bourd.) Rogers.,belonging to Cenatobasidium,Basidiomycotina.The anamorphs is Rhizoctonia cerealis Vander Hoeven and Rhizoctonia solani Kuhn.,belonging to Rhizoctonia,Deuteromycotina.The pathogen survives the summer and winter as sclerotium or mycelium in soil or attached in plant debris,becoming the main bacterial source of primary infection;the organic fertilizer carrying plant debris and diseased soil without maturity also can transmit the disease.When the seeds are germinated after sowing,the underground young roots and shoots of seedlings can be infected and damaged by the pathogen.In recent years,wheat sheath blight in Chinese wheat area is continuously occurred with heavy condition,this is mainly due to the cultivation of susceptible wheat varieties in large area.In addition,adjustment of cultivation system,abnormal climate,frequent introduction and planting promotion of varieties also cause the aggravating occurrence of wheat sheath blight year by year.