Ward J M J, Laing M D, Rijkenberg F H J
Cedara Agricultural Development Institute, Private Bag X9059, Pietermaritzburg 3200, South Africa.
Department of Microbiology and Plant Pathology, University of Natal, Private Bag X01, Scottsville, 3209 South Africa.
Plant Dis. 1997 Jan;81(1):41-48. doi: 10.1094/PDIS.1997.81.1.41.
Timing and frequency of fungicide treatments for management and control of gray leaf spot of maize, caused by Cercospora zeae-maydis, were quantified with the logistic model and area under disease progress curve (AUDPC). Control was most effective when spraying commenced as disease severity levels reached 2 to 3% of the leaf area blighted and when lesions were restricted to the basal five leaves of the maize plant. Highest grain yields were achieved with treatments providing disease control until the crop was physiologically mature. To provide this length of control, the frequency and number of fungicide applications varied with the stage of host development when disease was first apparent; with early infections, more fungicide treatments were necessary to provide protection until physiological maturity. Yield responses to fungicides appeared to be a function of the growth stage of the host when sprays were initiated, the amount of disease at spray date, the length of fungicide control, and effective control through to physiological maturity.
利用逻辑模型和病害进展曲线下面积（AUDPC）对防治玉米灰斑病（由玉米尾孢菌引起）的杀菌剂处理时间和频率进行了量化。当病害严重程度达到叶片枯萎面积的2%至3%且病斑仅限于玉米植株基部的五片叶子时开始喷洒，防治效果最佳。通过在作物生理成熟前提供病害防治的处理获得了最高的谷物产量。为了提供这种防治时长，杀菌剂的施用频率和次数会因病害首次出现时寄主发育阶段的不同而有所变化；对于早期感染，需要更多次的杀菌剂处理来提供保护直至生理成熟。杀菌剂的产量响应似乎是开始喷洒时寄主生长阶段、喷洒时的病害数量、杀菌剂防治时长以及直至生理成熟的有效防治的函数。
