Causal Organisms And Impact Factors Of Corn Ear Rot And Resistance Of Corn Varieties To Fusarium Ear Rot In Sichuan

Corn is one of the three major grain crops on the world. In recent years, corn ear rot has generally occurred in late growth stage or the storage stage after harvest. Now, it has become a major constraint in the development of corn production for its harmfulness. It is very important to find out the pathogen composition and the dominant species of corn ear rot in this study. And the objectives of this study were to determine the causal organisms and impact factors of corn ear rot, and resistance of corn varieties to the disease caused by Fusarium moniliforme.In this research, pathogens of corn ear rot were obtained from 12 regions of Sichuan Province in 2009. According to the identified results, there were 9 species of pathogenic fungi:Fusarium moniliforme, Fusarium graminearum, Thichoderma sp, Rhizoctonia sp, Penicillium spp, Aspergillus niger, Aspergillus flavus, Mucors sp, Trichothecium roseum, Nigrospora oryzae, Bipolaris sorokiniana. The separation frequency for Fusarium moniliforme was the highest, which was up to 51.1% and is regarded as the dominant species of corn ear rot, in Sichuan Province; Followed by Trichoderma, whose separation frequency was 19.7%. In addition, Fusarium graminearum also has a high separation frequency. while Rhizoctonia and Mucor has the lowest separation frequency. The study showed that the density increased to 3300/mu could reduce the incidence of the disease. However if we continue to increase the density, it would lead to a higher incidence of ear rot. According to observation, corn ear of insect pests is a major cause of ear rot.During 2009 and 2010, resistance identification tests were carried out on 138 varieties with toothpick inoculation, The results show that:7 varieties were preliminary selected as high resistance(HR) varieties accounted for 5%, which were Wangyu18, Zhengxing No.3, Zhengda 2393, Shenzhu No.7, Ziyu No.2, Chuandanqingzhu No.1, Yuyu No.18; 54 varieties were resistance(R), accounted for 39%; 47 varieties were middle resistance, accounted for 34%; 24 varieties were Susceptible(S) which occupled 17.9% and 6 varieties were highly susceptible(HS) which accounted for 4.5%.