Abstract
The relationship between the number of pesticide spray applications and the ratio of undamaged soybean was investigated from 2002 to 2003 in a soybean field at Shintone-cho, Ibaraki Prefecture. Stinkbug density and the ratio of undamaged soybean were negatively correlated with the number of pesticide spray applications. Damage to soybean varied among the years and experimental blocks. In order to harvest 85% and 90% undamaged soybean, the insecticide needed to be sprayed for one and two times, respectively. These results imply that the number of pesticide spray applications can be reduced from three times to two times in soybean production at Shintone-cho.
