Severe Corn Rootworm Injury Reported in New York Fields

By Blake Jackson

Researchers and extension specialists are reporting significant corn rootworm damage in several continuous corn fields across Central New York during the 2026 growing season.

According to Marcelo Dimase of Cornell University, Janice Degni, Erik A. Smith, and Mike Hunter of Cornell Cooperative Extension and Cornell Integrated Pest Management, affected fields have been identified in Onondaga, Cortland, Cayuga, and Madison counties.

Field evaluations revealed unexpected root injury and goosenecking in 22 corn fields. Using the Iowa State 0-3 root injury scale, average injury ratings ranged from 1.65 to 2.33, indicating substantial root damage. Researchers note that each damaged root node can result in roughly 15% yield loss, making rootworm infestations a significant economic concern for growers.

The damaged fields included hybrids containing AMXT, Qrome, Vorceed, and Duracade Viptera Bt trait technologies. Most growers also reported using medium- to high-rate neonicotinoid seed treatments.

However, researchers emphasized that the observations only document injury and do not confirm insect resistance or identify the exact cause of reduced control. Further testing will be needed before drawing conclusions about resistance.

A common factor among many affected fields was the repeated planting of corn, which can increase corn rootworm pressure over time. Researchers say the findings highlight the importance of monitoring fields, preserving resistance management strategies, and diversifying pest control approaches.

Growers are encouraged to inspect fields for lodging and adult beetles, particularly in areas with multiple consecutive years of corn production. Digging and washing root systems can help determine the severity of root pruning, while detailed records of hybrid traits, seed treatments, crop history, and insecticide applications can support future management decisions.

Experts recommend rotating heavily damaged fields out of corn whenever possible, as crop rotation remains one of the most effective tools for controlling corn rootworm populations in New York.

For operations that continue growing corn, specialists advise combining multiple management practices rather than relying on a single control method to reduce future rootworm pressure.

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