Abstract: By means of artificial inoculation, the infection difference of 6 wheat varieties to wheat sharp eyespot disease (Rhizoctonia cerealis )was compared.The disease incidence of varieties at their seedling stage could not reflect the difference of infection among them, and it was available to use disease index to compare the infection difference at their late milking stage.It was considered that the growth stage of host affected the relationship between incidence and severity.The regression analysis shows that the classification based on disease index in internal and external stems could decrease the errors of field investigation, and save time and manpower.

Key words: Rhizoctonia cerealis, Variety, Difference of infection, tide, biogenic silica, dissolved silicate, vegetation zone, estuarine wetland