Studies On Chemical Control Strategies Of Main Diseases On Rice Plants In Fengtai County, Anhui Province

Systematical investigation on rice diseases was carried out in Fengtai county, Anhui province in this paper. The major diseases were rice sheath blight, false smut, rice stripe virus disease, rice black-streaked dwarf and rice blast disease in whole rice development stage. The area of rice sheath blight reached one hundred thousand acres or more per year, and the symptom of the disease were emerge on rice plants in early July, and the disease severities expanded rapidly in middle-late rice development stages.Fungicides selection for rice sheath blight and false smut were conducted. The results showed that12per cent compound of anisole and validamycin A was safe for rice plants when application one time on booting stage and rupturing stage or rice respectively. The control effect of12per cent anisole and validamycin A was optimal when spray40grams per667square meters and the control effects of diseased plant ratio and disease index were54.3percent and69.3percent respectively, which was slight higher than the effects of two control fungicides. The control effects of the dosage for diseased rice ears and disease index of rice false smut were78.5percent and65percent respectively, which were higher than the effect of validamycin A, but lower than the effect of30per cent compound of difenoconazole and propiconazole. There was no significant difference among the tested fungicides by variance analysis.The seed dressing of10per cent ethiprole suspending concentrate promoted obviously the growth of direct seeding rice plants. The combination effect of seed dressing of20ml. per667square meters and spray of40ml per square meters for small brown rice planthopper reached87percent after7days, similar to the effect of pymetrozine, and the control effect would reach over95percent after14days. The control effect for rice stripe virus disease was82.4percent and would rise to96.5percent after30days.The combination effect of70%propineb+75percent trifloxystrobin and tebuconazole for controlling diseased plant ratio of rice sheath blight was the best among tested fungicides combinations, which value reached99.6per cent, and was significant higher than those of validamycin A treatment and75per cent tricyclazole treatment. The control effect of the combination for disease index of rice sheath blight reached100per cent, significant higher than that of75per cent tricyclazole treatment, but no significant difference to other fungicide treatments. The75per cent trifloxystrobin and tebuconazole for controlling rice false smut was the best combination, the control effect of which for diseased rice ears and disease index both reach over99per cent. Based on predicted yield experiments, the combination of75per cent trifloxystrobin and tebuconazole for controlling rice sheath blight and false smut had obviously effect for protecting production and increasing production.