The Return of Corn Rootworm

The Return of Corn Rootworm

For the past several years, Western Corn Rootworm have been isolated to just a few hot spots across the Corn Belt and in heavy continuous corn acres. Other areas were beginning to wonder if the corn rootworm problem had disappeared completely. But 2020 is proving that the Western Corn Rootworm is one of the most resilient pests’ growers face.

The AgriGold agronomy team has been working as a part of a seed industry collaborative effort capturing CRW beetles for the past several seasons. The sheer number of beetles being captured in 2020 are staggering. In fact, this has been the most documented root feeding and adult beetle numbers AgriGold has seen since 2013. The root cause of the population boom is being attributed to the mild 2019 winter conditions.

Impact Across the Corn Belt

“The Eastern corn belt has seen a huge rise in CRW beetle populations,” says John Brien, AgriGold Eastern Agronomy Manager. “The traditional heavy corn-on-corn areas of Illinois and Northern Indiana are seeing big beetle numbers as well as non-traditional CRW areas like Ohio.”

“The western corn belt has its usual hotspots of corn-on-corn and CRW issues. However, those areas have reached a boiling point in 2020,” says Dustin Bowling, AgriGold Western Agronomy Manager. “The severity of the situation really came to light after early July storm systems caused numerous corn acres to root lodge. Upon field investigations, our agronomists quickly correlated the damage to long time corn-on-corn fields and heavy CRW feeding.”

Management Strategies

Adult CRW beetle captures are running at high enough levels that Bowling and Brien say many growers will need to begin addressing this pest in 2021. Now is the time for growers to be walking fields to evaluate beetle numbers and talking with their agronomists about strategies for success in 2021. Below are several strategies that Bowling and Brien suggest for managing corn rootworm.

 

  • Rotate fields with heavy CRW pressure to a non-host crop like soybeans. This has been the most effective way to curb CRW population throughout the history of this pest.
  • Scout and spray for CRW adults in 2020. An average of .75 to 1 beetle per plant, or an average of 6 beetles per week caught by a sticky trap, could signal possible economic damage for corn planted the following year.
  • Utilize in-furrow insecticide in 2021. Fields in 2020 that combined in-furrow insecticide with below-ground trait protection drastically decreased the amount of root feeding and lodged corn.
  • Rotate below-ground trait protection modes of action. AgriGold has a broad portfolio of below ground trait offers, including: SmartStax RIB Complete, Agrisure Duracade 5222 E-Z Refuge, and Agrisure Viptera 3111.