A Study on the Damage and Economic Threshold of the Soybean Aphid at the Seedling Stage

Abstract

Both plot inoculation experiments and field pest scouting at the seedling stage indicated that soybean yield losses were closely related to the number of soybean aphids and the proportion of plants colonized by soybean aphids. The main factors affecting the soybean yield were decrease in plant height and number of pods and seeds, owing to injury by soybean aphids at the seedling stage. Under existing production conditions, the economic injury level was 3.36%. The control threshold was 500 soybean aphids per 100 plants, with 35% of plants colonized by soybean aphids.