辽宁春玉米弯孢菌叶斑病为害损失及经济阈值研究

目的]从玉米弯孢菌叶斑病的病级和病情指数的角度研究辽宁春玉米弯孢菌叶斑病的为害损失及其经济阈值。方法]以玉米品种沈单16为试材,设人工接种玉米弯孢菌叶斑病菌5个梯度（5.0×104、1.0×105、2.5×105、5.0×105、1.0×106孢子/ml）,另设对照处理,完全随机区组设计。病菌接种后7d进行发病级数调查,其病情严重度按国家标准分6级调查。结果]随着玉米弯孢菌叶斑病病级的增大,穗粒数、百粒重、产量都呈下降趋势,玉米弯孢菌叶斑病病级和病情指数与穗粒数、百粒重和产量损失率呈极显著正相关。若以病级为防治玉米弯孢菌叶斑病的经济阈值,则平均病级为0.45;若以病情指数为防治指标,则病情指数为14.10。结论]该研究为辽宁春玉米弯孢菌叶斑病的防治和经济阈值的科学制定提供了参考。

Studies on Damage Caused by Spring Maize Curvalaria Leaf Spot and its Economic Threshold in Liaoning Province

Objective] The propose was to study on the damage caused by spring maize Curvalaria leaf spot and its economic threshold in Liaoning Province from the view of disease level and disease index of maize Curvalaria leaf spot.Method] With maize variety Shendan 16 as the tested material,5 gradients(5.0×104,1.0×105,2.5×105,5.0×105,1.0×106 spores/ml)were set up for artificial inoculation of maize Curvularia leaf spot fungi and the CK treatment was also set up in the field test with the completely randomized block design.After the fungi were inoculated for 7 d,the investigation on the disease level number was conducted and their disease severity was divide into 6 levels according to the national standard.Result] With the increase of maize Curvularia disease levels,the grain number,grain weight,yield showed the decreasing trend.The maize Curvularia leaf spot disease level and disease index had a very significant positive correlation with the loss rates of the grains of ear,weight of hundred grains and the yield.If the disease-level was taken as the economic threshold level of controlling maize Curvularia leaf spot,the disease-level was average of 0.45;if the disease index was taken as the controlling index,the disease index was 14.10.Conclusion] The study provided the reference basis for the scientific establishment of economic thresholds for controlling Curvularia leaf spot of spring maize in Liaoning.