北海道におけるダイズ紫斑病に対する薬剤散布適期

抄録

Purple seed stains in soybean caused by Cercospora kikuchii is a prevalent disease in the main island of Japan. Recently, there has been an increase in spread of this disease increases to Hokkaido, which is the main soybean production area and located in the northernmost part of Japan. However, little is known about control measures for the disease in Hokkaido. Therefore, optimal timing of the fungicide spray against the disease was investigated. From 2012 to 2013, four field trials using three varieties (Yukihomare, Toyomusume, and Yuzuru) revealed that optimal spray timing was between 10 and 20 days after flowering time. This period is 10 days earlier than that of the main island of Japan.