玉米灰斑病发生流行规律及品种抗病性

 玉米灰斑病近年来发生严重,对玉米生产造成很大危害。玉米灰斑病病原菌主要在病残体上越冬,病残体上的分生孢子在7月中下旬有较高的萌发率。玉米灰斑病于7月上旬开始发病,在8月中下旬至9月上旬为发病盛期。田间温度、相对湿度和7月份降雨量都影响病害的发生和发展。降雨量大、相对湿度高、气温较低的环境条件有利于病害的发生和流行。玉米杂交品种和自交系对玉米灰斑病表现的抗性差异较大,感病的杂交品种有掖单13、丹605和丹2181,抗病杂交品种有丹中试61、辽9505、沈9728、辽306、丹3079、丹3034;抗病的自交系有9046、冲72、J599-2、齐319、丹黄25、79532、598,凡具有热带血缘的自交系都是抗病的。

Epidemics of gray leaf spot of corn(Cercospora zeae-maydis) and varietal resistance

Gray leaf spot of corn, caused by Cercospora zeae-maydis Tehon and Doniels, has become one of the most signi_ ficant yield-limiting diseases of corn in China, especially in northeastern China. The pathogen overwinters in diseased plant residue and conidia have high germination rate, even in the next mid and later July. In this study, the disease occurred in early July and became prevalent from mid or late August to early September. The temperature, relative humidity (RH) and rainfall in July significantly affected the disease development. Rainy, humid and cool conditions are favorable to widespread of disease epidemics. Different varieties and inbred (or breeding) lines exhibited different disease resistance. Among the tested varieties and inbred lines, such as Yiedan13, Dan 605 and Dan 2181, were susceptible, while Danzhongshi 61, Liao 9505, Shen 9728, Liao 306, Dan 3079, Dan 3034 were resistant. The inbred lines including 9046, Chong 72, J599-2, Qi 319, Danhuang 25, 79532 and 598 were found to be resistant. It is found that the varieties derived from tropical germplasm were highly resistant to the disease.