Improving Formulation Of A Conidial Water Suspension Concentrate Of The Mycoparasite Coniothyrium Minitans And Evaluation Of Its Biocontrol Efficacy Under Field Conditions

Coniothyrium minitans is a mycoparasite of Sclerotinia sclerotiorum. Previous studies have shown that Coniothyrium minitans has great application prospect. In foreign countries C. minitans has been developed into commercial products applied to control sclerotinia stem rot of vegetables and field crops. Our laboratory research group formulated a conidial water suspension concentrate of C. minitans with conidia as active ingredient. But the shelf-life is short. So the subject of this study is optimizing and improving the conidial water suspension concentrate of C. minitans in the preparation and application. The study mainly from the following aspects to conduct: the fermentation of C. minitans, the formulation of water suspension concentrate, the biology activity and field experiments. Some studies indicate that trehalose and glycerol can protect bioactivator from the influence of biotic and abiotic stresses. So we also studied the effect of trehalose and glycerol to the survival and storage of conidia. Include the conidiation, germination and survival after adding trehalose and glycerol in the fermentation of C. minitans. And we also test the effect of shelf-life to adding trehalose and glycerol to the water suspension concentrate. The conidia of water suspension concentrate can parasite and destroy sclerotia of S. sclerotiorum, the rot index was tested too. At last, the field experiments were conducted to test the effect of conidial water suspension concentrate.The results of the study are as follows:(1) The solid phase fermentation of C. minitans was optimized to be simple and convenient. Adding0.5%trehalose to ferment can improve production and survival rate of conidial, and prolonged the survival time of conidial.(2) Adding0.5%trehalose to the conidial water suspension concentrate can prolonged the survival time of conidial. And the paroline prevent the conidial water suspension concentrate from contaminative microbes over a period of time.(3) The adding of trehalose and glycerol has no negative influence to the survival of conidia, but can improve the ability of parasite and destroy sclerotia of S. sclerotiorum. So the final formula is adding0.5%trehalose and paroline to the original formula. The observation of electron microscope indicates the differences between dead conidial and live conidial.(4) The field experiments from2012to2014indicate that the conidial water suspension concentrate after improving can prevent and control sclerotinia rot of colza effectively, the average control effect is about50%.