Double dose of rootworm control

Published on: 14:42PM Oct 23, 2009
Caydee Savinelli

University entomologists observed lower root ratings from a combination of soil insecticide and Bt traits in plots with heavy rootworm pressure. Is this combination necessary? Two reasons to consider this strategy include:
  • Dissatisfaction with the level of protection from Bt corn hybrids
  • Problems with soil insects other than rootworm, like wireworms, white grubs, grape colaspsis, seed corn maggot, and others
Other entomologists say using two modes of action for rootworm control could play a role in resistance management, and combination treatments may offer longer-term benefits. 
How do you decide if you would benefit from a double dose of corn rootworm control? Consider the following questions:
  • Is there heavy rootworm pressure?
  • Do I need to manage insects with multiple modes of action?
  • Is there heavy white grub pressure?
  • Are past wireworm pressures a concern?
  • Is there potential for early-season weed competition? – (Pest population growth accelerates in early weed cover.)
  • Is there a history of grape colaspis?
  • Do I plan to plant early? (Low-dose RW-traits may not last long enough to protect against late-season feeding.)
  • Are cutworms a threat?
Answering “yes” to any of these questions indicates that you should seriously consider a combination of corn rootworm control to protect your crop.