Experts urge careful scouting before spraying flowering soybeans
Corn earworms continue to be one of the most damaging insect pests affecting soybean production. The pest can reduce yields through feeding damage and increase production costs when control measures are needed says Dominic Reisig, Professor and Extension Specialist, Entomology & Plant Pathology at North Carolina State.
The insect is most seen later in the growing season. Populations often build in corn fields first, where larvae feed before moving through their life cycle and emerging as moths. These moths later lay eggs in flowering soybean fields.
Researchers have also observed that some corn earworm populations arrive from southern regions earlier in the season. This movement may explain increased pest activity in certain early-planted soybean fields.
Many growers are considering whether soybean fields should be treated at the early flowering stages known as R1 and R2. Research suggests that treatment is often unnecessary during these stages. Soybean plants can naturally produce more flowers than they eventually convert into pods, allowing them to tolerate moderate flower feeding without significant yield loss.
However, environmental stress can change the situation. Drought, poor growing conditions, or other stress factors may reduce the soybean plant’s ability to recover from feeding damage.
Once pods begin developing at the R3 stage, growers should pay closer attention. Feeding on pods can have a greater effect on yield than feeding on flowers. Even so, soybean plants still have the ability to compensate by producing larger seeds or adjusting growth.
Recent research has shown that both determinate and indeterminate soybean varieties can recover from corn earworm feeding under favorable growing conditions. This recovery is more likely when plants are healthy and not under stress.
Experts encourage growers to scout fields regularly and monitor moth activity through light trap networks. These tools help identify periods when egg-laying activity is increasing.
Several insecticides remain effective for controlling corn earworms. Recommended products include Blackhawk, Denim, Intrepid Edge, Steward, and Vertento.
Growers are advised to avoid unnecessary use of broad-spectrum insecticides because they may reduce beneficial insect populations and contribute to outbreaks of pests such as soybean loopers and spider mites. Certain products, including Besiege, Elevest, and Vantacor, should not be used in soybeans.
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