Studies On The Formulation Of A Conidial Water Suspension Concentrate Of The Mycoparasite Coniothyrium Minitans

Coniothyrium minitans is a promising biocontrol agent (BCA) of Sclerotinia sclerotiorum, the causal agent of sclerotinia stem rot (SSR) of oilseed rape. C. minitans as a biocontrol agent has been extensive researched. In foreign countries C. minitans has been developed into some products and preparations for the control of SSR of vegetables and field crops. In domestic, the preparation technology of C. minitans has not been reported. Currently, determinate a formula of C.minitans is the key step to commercialize it. Combine a large-scale fermentation, with conidia as active ingredient, formulation of a conidial water suspension concentrate (CWSC) of C. minitans was formulated. Its main indicator, biology activity, field experiments and shelf-life was studied.Based on the conidia germination and the character of additives, a preparation of CWSC of C. minitans was formulated, the components of the CWSC of C. minitans were selected to contain 2×10 conidia/mL,3%～5% sodium lignosulphonate or calcium lignosulphonate (wetting and dispersing agent),0.3%-0.4% xanthan gum (the viscosity-adjusting agent),0%～5%ethanediol (the antifreeze agent),0%～5% dimethyl silicon oil (the defoamer agent),0.1%～0.2% ascorbic acid (the UV protectant) and 0.3% sodium penicillin and streptomycin sulfate (the antiseptic agent).The main indicator of CWSC was detected. Its conidia are higher than 2×109 conidia/mL. Suspension efficiency is higer than 90%. Dispersion is good, the conidia dispersed immediately, when diluted with water. Its pH value is from 5.3 to 5.5, suitable for survival of C. minitans. Centrifugal stability is excellent grade, does not appear stratification. The adaptability to water temperature and water quality are also qualified.The conidia germination of CWSC initial is higher than 95%. The conidia of CWSC can parasite and destroy sclerotia of S. sclerotiorum, the rot index is higher than 80%. Result of field experiments conducted in 2010 showed that application of the CWSC of C minitans on oilseed rape at the flowering time could significantly suppress sclerotinia stem rot. There was no significantly different on control effect between CWSC and Dimethachlon. In the plot in 2010 which sprayed with CWSC, the suppression effect on disease incidence rate is 35.0%, and the suppression effect on disease index is 52.9%. In the plot in 2011 which sprayed with CWSC, the suppression effect on disease incidence rate is 59.2%, and the suppression effect on disease index is 56.4%.In the field which sprayed with CWSC, the best suppression effect on disease index is 68.1%, and the suppression effect on disease index is 66.5%.The shelf-life of the obtained formula was tested. Results showed that low temperature is suitable for survival of conidia of C. minitans. The formulation can not be stored at high temperature (28℃), stored at 10℃and 20℃, the shelf-life was 35 days, and stored at 4℃, the shelf-life was 42 days. The shelf-life is short, and it is far from the standard. Further research is required to extend the survival of C. minitans of formulations.