The Incidence Characteristics Of Main Plant Diseases And Insect Pests On Paddy Rice In Recent Year In Yi Chun City And Their Infesting Reasons

In this thesis, the incidence characteristics of main plant diseases and insect pests on rice in Yichun city were systemic investigated and analyzed. The data show that the incidences of main plant disease and insect pests on paddy rice in recent years have some characteristics as below.The rice stem borer Chilo suppressalis caused the highest damage to paddy rice, especially in 2002, this pests break out on rice. The hatching date of the first generation larvae shifted to an earlier time year by year. The damage area of this pest gradually enlarged year by year. The late rice suffered gigantic losses from this pest.The rice plant hoppers caused much serious damage on late rice than on early rice. However, the injury area of early rice tended to enlarge in recently years.The rice leaf folder, Cnaphalocrocis medinalis showed an outbreak every two years in Yichun city. The second generation of Cnaphalocrocis medinalis generally made the most serious damage on rice in June every year.The infestation of rice blast magnaporthe grisea shows a phenomenon of "decrease on early rice but increase on late rice".In recently years, sheath blight of rice Rhizoctonia solani made the most serious harm in 1997 and 2000. 71 % of the rice areas were infected by the sheath blight of rice in different degree.The incidence of main plant diseases and insect pests showed some differences in different rice cultivated forms.The main reasons which result in main plant diseases and insect pests outbreak were mainly due to the warm temperature conditions in winter and spring seasons, prominent change in farming patterns, illogical use in pesticide and the overlook of agricultural control measures.In this paper, some advices in control measures to the main plant diseases and insect pests in rice were put forward.