Illinois Field Crop Applicators Practice Test

Which pest is primarily responsible for causing yellowing leaves, curling leaves, and pod count reduction in soybeans?

1. Spider mites

2. Soybean aphids

3. Bean leaf beetles

4. Alfalfa weevils

The correct answer is: Soybean aphids

The soybean aphid is a tiny, sap-sucking insect that can significantly impact soybean plants. When these pests infest soybeans, they feed on the plant's sap, which leads to a range of symptoms including yellowing and curling of leaves. This is primarily due to their feeding weakening the plant and causing stress, which disrupts its normal growth and nutrient transport. Furthermore, soybean aphids can reduce pod counts by diminishing the plant's overall health and vigor, leading to lower yields. The overlap of these symptoms makes soybean aphids particularly notorious among soybean pests, as they can cause both visual signs of damage and quantitative losses in yield. This knowledge is crucial for effective pest management and timely intervention to mitigate damage and support healthy soybean production.