Control Effects Of Three Fungicides To Ustilago Maydis L.

Ustilago maydis L. is a common disease of maize in agricultural production, which iscaused by the infection of Ustilago maydis. In recent years, owing to the extensive planting ofsingle varieties，agricultural tillage system and the climate, the disease is spread to manymaize production area and becoming more and more serious. At present, there is little studyabout the disease both at home and abroad, especially having no useful fungicide to it. Thetest lists three better fungicides to control Ustilago maydis on the basis of virulence indoortests. By a field experiment, the test aims at studying the control effect of the disease, theprotection of enzyme activity, chlorophyll content, MDA, soluble protein and effect on yieldwith Ustilago maydis incidence level conditions was studied, Provide a theoretical basis foryield loss prediction and scientific control of production of the disease.1. The spore germination method was used to determine the toxicities of six bactericidesto Ustilago maydis. The results showed that both mancozeb and thiram showed strong toxicityagainst Ustilago maydis, and EC50for spore germination was2.21mg/L and4.37mg/Lrespectively, and EC50for basidiospore growth was6.75mg/L and1.25mg/L respectively;The EC50value that fludioxonil inhibit spore germination was5.25mg/L, and the fludioxonilshowed the strong inhibition on basidiospore growth. The basidiospore had a slight growthafter treated with pharmaceutical concentration of0.25mg/L, but serious deformity happened,and they can`t continue to grow; the toxicity of difenoconazole and carbendazim againstUstilago maydis was slightly weaker.2. Field trials of quantitative artificial inoculation about2years were conducted to studythe control effect of Ustilago maydis L. with different concentration of three fungicides andits effect on control and the yield. The results showed that, with concentrations increasingbetween different treatments of25g/L fludioxonil FS, strengthen the corn protection, improvethe control effect, promoting the effect of yield increase compared with the control. Theprotective effect, control effect and the yield reach the highest level, the control effect reached64.61%, the yield increased18.65%compared with the control, when the concentration was36mL/10kg seeds; The protective effect, control effect and the yield reach the highest level,the control effect reached54.96%, the yield increased19.41%compared with the control,When the concentration was30mL/10kg seeds of60g/L Raxil FS.3. Has studied the treatment and protection of treatment with different concentration offludioxonil, tebuconazole and thiram in maize of inoculated Ustilago maydis by a fieldexperiment. The results showed that pre-and post in the pathogenesis of Ustilago maydis, various treatments on chlorophyll content, Soluble protein content, protective enzyme in thesame physiological effects of laws. the effect of protection and treatment increased withconcentrations between different concentrations increase of60g/L Raxil FS, the promotionreach the highest level when the concentration was20ml/10kg seeds; When the concentrationwas36mL/10kg seeds of25g/L fludioxonil FS, the promoting effect reached highest.; Whenthe concentration was36mL/10kg seeds of50%thiram WP，the promoting effect reachedhighest.