| Seed dressing is economical new pesticide formulation that is based on the troditional pesticide agents, added film-forming agents and something else to. Seed dressing have innate absolute advantage in controlling soil born and seed transmission plant disease. Sunflower sclerotinia rot is worldwide soil born and seed transmission crop disease, showing rot on stem, head, leaf, and root. The stem and root rot are the main symptom of Sunflower sclerotinia rot in western of China. In this study, sclerotinia rot is the major control objects, powder used for seed dressing was researched through added agglutinant, disintegrant, warning colouration, biocontrol bacteria and fungicide that has highest virulence to the Sclerotinia sclerotiorum throgh toxicity determination. At last, the control effciency and safety was evaluated through test in greenhouse and field.The mixture of clay 40% and kaolin 60% was selected as the stuffing for its higher absorption rate, through the screening of marterial and percentage. In the procedure of agglutinant selection, the CMC and sodium lignin sulfonate were screened out as the agglutinant initially. Then, the best percentage of CMC was confirmed at 7%, and sodium lignin sulfonate 5%. The best disintegrant was selected by measuring disintegration time. The result showed that (NH4)2S04 was the best disintegrant, when sodium lignin sulfonate was the agglutinant, percentage of (NH4)2SO4 was 1%, if the CMC was the agglutinant, percentage of (NH4)2S04 was 3%. In this study the formulations of powder used for seed dressing was confirmed, after the fungicides type was screened by toxicity determination at last.The inoculum concentration of Sclerotinia sclerotiorum bran was choosed at 0.2% and disease severity was divided into 5 grades, through inculating different size Sclerotinia sclerotiorum bran. The results in greenhouse showed that all agents had better control efficiency, control efficiency of agent containing carbendazim, dimethachlon and S-16 biocontrol bacteria strain was best, when the chemical fungicide percentage is 1%,3%,5% respectively, the control efficiency was 83.72%, 75.81%,84.51%. The result in field showed that the control efficiency agent containing carbendazim and S-16 biocontrol bacteria was 78.67% in Sanrui company experimental field, and control efficiency of agent containing carbendazim, thiram and S-16 is 76.47%. The disease severity of CK in Yongli experimental field was low.In the study of safety and sability of powder used for seed dressing, the best condition for detecting residue of fungicides was confirmed, after screening different detecting condition. The best detecting wavelength was 210nm, mobile phase was acetonitrile:water(60:40), flow was 0.75mL/min, extraction liquid was acetonitrile. The residue of fungicide can not be detected after seeding 110 days, using selected detecting condition. The colony forming units of S-16 in soil was reducing as time goes on. The agents had no obvious effect on the growth and development of sunflower. Above all, there were no effect on the soil microorganism diversity after using powder agents used for seed dressing, by PCR-RAPD analysis method. The colony forming units of S-16 in powder agent dropped to 40%, after stored of 3 months.It is a simple effective method for control sunflower Sclerotinia rot to dress seed thrugh using powder used for seed coating. |
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