Is the Billion Dollar Bug in Your Fields?
BY Dairyland Seed Agronomy Team
Corn rootworm (CRW) poses a significant threat to corn production in the U.S. Most prominent in the South and Midwest, CRW is also lurking in the northern states, and Dairyland Seed customers who don’t think they have CRW in their fields most likely do says Travis Lee, Corteva Research Scientist, and Corn Breeder. This pest, often dubbed the “billion-dollar bug,” is known for causing over $1 billion in economic damage yearly.
Two primary CRW species of concern exist: the Western Corn Rootworm and the Northern Corn Rootworm. Both species pose a threat at various stages of their life cycle. According to Lee, the larvae feed on corn roots, compromising the plant’s ability to absorb nutrients and water. This can lead to stunted growth, increased susceptibility to drought, and in severe cases, the plants may suffer from lodging.
“Rootworm larvae can prune nodal roots down to nothing, impacting nutrient uptake and leading to symptoms of drought stress,” explained Lee. “During wet conditions and wind events, plants may be found flat on the ground due to lack of root structure.”
WHAT YOU SHOULD KNOW
CRWs go through a life cycle that starts with eggs in the soil, typically hatching when fireflies appear in June. The larvae feed on the roots, and the pests usually have moved on once visual damage is apparent. Adult beetles emerge later in the season, feeding on the leaf material and silks, which can interfere with pollination.
“One challenge is that corn rootworms are incredibly resilient,” noted Lee. “They can navigate preventative measures effectively, evolving to tolerate insecticides and other control methods.”
Lee says scouting is crucial for early detection. Farmers should dig up plants in June to inspect roots for signs of feeding. Minor feeding results in pits in the roots, while severe infestations can prune lateral roots entirely. Identifying the type of rootworm is also vital, as the northern corn rootworm can exhibit extended diapause, making crop rotation less effective.
DAIRYLAND SEED OFFERS NEW VARIETIES FOR CRW
Dairyland Seed has developed two new corn traits, Vorceed® Enlist® and PowerCore® Enlist Refuge Advanced®, which combine multiple action modes against insects and herbicide tolerance. These traits are available in select hybrids as part of an introductory launch for the 2025 season and will expand to a full range of products in 2026.
Vorceed® Enlist® corn uses RNAi+Cry3Bb1 technology to suppress the expression of specific genes in corn rootworms, in combination with proven Bt proteins in DP4114 causing them to die when they feed on the plant. It also provides multiple modes of action against above- and below-ground pests. Additionally, it provides all the benefits of the Enlist® weed control system with multiple herbicide tolerances, allowing you to use 2,4-D choline, glyphosate, glufosinate, and FOP herbicides for weed control.
PowerCore® Enlist® Refuge Advanced® corn includes three proteins that form a pyramid of protection against aboveground insects. It targets European corn borer, Southwestern corn borer, Fall armyworm and Black cutworm with different modes of action, reducing the risk of resistance development. It also has the same herbicide tolerance as Vorceed® Enlist® corn.
Both traits offer single-bag, integrated refuge solutions, meaning you do not need to plant a separate refuge area for insect resistance management.
ACTION STEPS
Managing corn rootworm requires a multi-pronged approach:
Scouting and Monitoring: Regularly scout fields for root health and beetle populations.
In-plant Protection: Products like Vorceed® Enlist® and PowerCore® Enlist® offer in-plant protection against CRW with multiple modes of action. Talk to your Dairyland Seed District Sales Manager about varieties available for 2025.
Soil and Seed Insecticides: Applying soil insecticides when planting or using insecticide-treated seeds can help manage larval populations.
Aerial Applications: During high beetle populations, especially around pollination, aerial applications can reduce adult beetle numbers and prevent silk clipping.
Crop Rotation: Rotating corn with non-host crops like soybeans can disrupt the life cycle of CRW. However, Northern corn rootworm’s extended diapause can reduce the effectiveness of this method.
Corn rootworm remains a persistent threat to U.S. corn production, necessitating vigilant management strategies. Utilizing products like Vorceed® Enlist® and PowerCore® Enlist®, implementing crop rotation, and regular scouting can help mitigate the damage caused by this pest.
“There’s no single magic bullet for managing corn rootworm. It requires a comprehensive approach to control high populations and protect your crop investment,” emphasized Lee.