长春地区玉米大斑病流行指数增长期的病情增长研究

对长春地区玉米大斑病流行指数增长期的病情增长进行了研究。结果表明,一般年份长春地区中等感病品种玉米大斑病的指数增长期大约为田间病害开始产生至8月初,是病害预测和防治的关键期。玉米大斑病的日增长率在0.02～0.2左右,降雨与随后第10天左右的病害日增长率高度正相关。单个玉米大斑病病斑增长时间可持续2个月左右,病斑长度可达20cm以上,宽度可达1.5cm以上,单个病斑增长(长、宽、面积)随时间变化的曲线均接近直线。雨后转连续数日晴天有利于病斑扩展。

The Studies on the Increase of Disease of Exserohilum Turcicum in the Exponential Stage in Changchun Region

The studies on the increase of disease of Exserohilum turcicum in the exponential growth stage in Changchun region. The results showed that the exponential stage of Exserohilum turcicum in median-susceptible variety was about from the beginning of disease developping to the period of July 30 to early August,it was a crucial stage of prediction and management of Exserohilum turcicum turcicum. The apparent infection rate of Exserohilum turcicum was about 0.02 -0.2, and it was highly positive correlation with the tenth day or so after raining. The increased stage of single lesion can last 2 months. The length of lesion can reach over 20 cm, and width can reach over 1.5 cm. The relation curve between the areas of single lesion expansion and day-old of the lesion is straight line. It was several continued clear days after raining that was beneficial to expansion of lesion.