Cutworms: check the weeds on your fields!

Zunel van Eeden explains why understanding the ecological interplay between cutworms and weeds is crucial for effective pest management. Producers should disrupt the life cycle of cutworms to minimise crop damage.

- Zunel van Eeden

In the agricultural environment, insect pests are of key interest due to the fact that their development and damage potential are influenced by the changing climate and agricultural practices that have been adopted along the way.

Among the various pests that threaten crop yields, cutworms have re-emerged as significant challengers to maize cultivation over the past three planting seasons. These polyphagous pests are highly adaptable and capable of feeding on a wide range of plant species, including economically vital crops like maize, soya bean, and sunflower, which are commonly grown in the Highveld region of South Africa.

Understanding the ecological interplay between cutworms and weeds is crucial for effective pest management, particularly in the Highveld production region, where cutworm infestations can lead to significant reductions in crop density and yield.

A few factors that predispose maize fields to cutworm outbreaks include, but are not limited to, previous cutworm infestations, the timing of the removal of weed coverage, and environmental conditions like temperature and soil moisture influencing larval survival.

Cutworm larvae undergo six larval stages before pupation and moth emergence. During these stages, they rely heavily on available food sources.

Large instar larvae, which are more damaging, are often observed to feed on weeds stems before transitioning to newly emerged maize seedlings.

However, the presence of small larvae can be identified by their characteristic leaf damage that have a shot-hole appearance.