Studies On Control Of Wheat Sharp Eyespot Caused By Rhizoctonia Cerealis With Trichoderma Viride

Wheat sharp eyespot, a major soil-borne disease caused by Rhizoctonia cerealis , was widely distributed in Huanghuai winter wheat area, northwest spring wheat area and the middle-lower regions of Yangzi river. At present, there is no resistant varieties available and the only way to control this disease effectively is chemical control with pesticide, which resulted in environment pollution and emergence of pesticide resistant strains. Therefore,it is necessary for us to find an alternative method to take the place of chemical protection. The usage of microorganism and its metabolic substance for biocontrol against the plant disease could overcome the shortage of chemical protection and had theoretical significance and applicable value.In this study, three R. cerealis and two Trichoderma viride were isolated from wheat sharp eyespot plants respectively. One strain of R.cerealis named Ry-1 ,which is a high pathogenic strain ,was selected after comparing the pathogenic ability among the three Rhizoctonia strains by pathogenic test . One strain of T. viride named Ty-1 ,which could inhibit the growth the pathogenic fungi efficiently was selected after pairing the two strains of T. viride and the pathogenic fungi of Ry-1 respectively.The model of action of inhibition between T. viride Ty-1 and R .cerealis Ry-1 was employed by pairing the two fungi on the plates and the results showed that the Ty-1 could inhibit the growth of Ry-1 by coiling around pathogen hyphae, penetration,and subsequent dissolution of the host cytoplasm which suggested that mycoparasitism might plays a very important role in their interaction.The biological efficacy indoor in pot tests of the strain of T. viride against the disease of sharp eyespot was tested. The results showed that the efficacy reached to 89% and the effect of plant promotion of Ty-1 to the seedlings of wheat was also found . It showed that the percentage of emergence of wheat after incubation of T. viride was more 15% than that of control and the weight of the seedlings exceed nearly 50% over that of control .The biological efficacy outdoor in pot tests of the strain of T. viride against the disease of sharp eyespot was tested. The results showed that the efficacy reached to 91.9% and the effect of plant promotion of Ty-1 to the seedlings of wheat was also found . It showed that the percentage of emergence of wheat after incubation of T. viride was more 10% than that of control and ,the weight of wheat plants increase more than 40% during the early growth phase than that of control which were not treated with T. viride and the percentage of ear of grain more 38.84% than that of control.The experiment of protecting wheat from the disease of sharp eyespot in field failed owing to lack of disease. No plant growth promotion was found after inoculating Ty-1 on wheat in field , which might be the results of some ecological factors and needed to study further.According to the results previously, it suggested the strain of T. viride Ty-1 might be a potential biocontrol strain used to control sharp eyespot of wheat. Further studies should focus on the influence of ecological factors in the field condition.