Cooperative
Extension
Service


University of Illinois
at
Urbana-Champaign


No. 14/June 25, 1998

Aerial Applications of Furadan 4F for Rootworm Larvae: Pest Management Approach

During the past week, reports of corn rootworm larval injury have escalated. Most of the cases have involved producers throughout east-central Illinois, where western corn rootworms have adapted to the annual rotation of corn and soybeans. In some instances, a soil insecticide was used; in other fields, no products were applied this spring. Despite all the wet weather this June, corn rootworm larvae have survived in sufficient numbers to cause impressive levels of root pruning. As we reported in issue no. 12 of this Bulletin, an insecticide applied during cultivation does not generally perform as well as a planting-time treatment. Because this June has been one of the wettest on record, cultivation rescue treatments are not an option. Also, we've received a few reports that some corn rootworm pupae are being found. This indicates that the larval feeding period will near its completion by late June, certainly by very early July. In essence, there aren't any good options at this point for rescuing a severely injured field. Unfortunately, some desperate producers are succumbing to poor advice offered by certain overzealous individuals for rootworm management. Specifically, that advice is to use Furadan 4F as an aerial rescue treatment to prevent further larval injury. That recommendation is irresponsible and should never have been made. Why? The track record of Furadan's performance (granular and/or liquid formulations), even when applied by ground as a rescue treatment, is extremely variable. The evidence of this inconsistency dates back at least to the early 1980s in experimental trials conducted by several universities. In University of Illinois trials, the performance of Furadan 4F applied as a cultivation treatment also has been extremely erratic and discussed for several years in many issues of this Bulletin.

If ground-applied treatments of Furadan offer at best marginal levels of control, why would anyone recommend an aerial application? Consider how very little of the actual toxin will ever reach the target organism. Most of the Furadan 4F will strike foliage of whorl-stage plants and never reach the ground. Furadan 4F will not translocate from leaf tissue to roots and kill larvae. Bottom line--the aerial application of Furadan 4F on whorl stage corn in an attempt to limit the latter stages of corn rootwormlarval injury is an irresponsible pest management decision. Unfortunately, all of us in the agricultural sector suffer from this kind of reckless recommendation.

Mike Gray (m-gray4@uiuc.edu) and Kevin Steffey (ksteffey@uiuc.edu), Extension Entomology, (217)333-6652