University of Illinois

No. 1/March 21, 1997

Have a Cup of Hot Chocolate... And Consider This

We recently became aware of a bit of advertising sent by DowElanco to many dealers in Illinois and Indiana, and we feel obligated to respond. You may have been one of the many folks to receive a small (5" x 7") folded card on which the invitation "Take a couple of minutes, have a cup of hot chocolate on us and consider this:" is printed over a picture of a bag of corn kernels. Inside, the information touts the virtues of using Lorsban 15G to "tr eat your first-year corn like all your corn." Obviously, the ad is intended to raise awareness of the problem with western corn rootworm larvae causing damage to corn planted after soybeans and to take advantage of that awareness by encouraging producers to buy and apply Lorsban 15G for protection against the problem. We believe the ad plays upon the fears of producers about a baffling problem and encourages the use of a soil insecticide as insurance against a problem that may not occur. The end result fo r a producer who uses a soil insecticide when the problem (in this case, rootworms in corn after beans) does not occur is a loss of about $15 per acre (the cost of the insecticide). No pest, no benefit. So, show us the money.

In many issues of this Bulletin since 1993, we have elaborated about the phenomenon of western corn rootworms laying eggs in soybeans. The problem is mystifying, and a lot of people are working hard to determine the why, what, and where of the problem. To date, researche rs and Extension entomologists in Illinois and Indiana have identified a relatively localized area where the problem has been verified. In Illinois, according to our research efforts and reports from the field, the problem with western corn rootworms caus ing damage to corn planted after soybeans has been verified in about 12 east-central counties, including Champaign, Ford, Grundy, Iroquois, Kankakee, Livingston, Piatt, Vermilion, and Will. Some testimonials to us have included eastern McLean County and a few possible incidents in the counties surrounding this area. However, these latter reports have not been verified. In DowElanco's ad, they reveal the problem area on a map of Illinois and Indiana to be much bigger than records verify. Their problem area extends as far west in Illinois as Peoria and Bureau counties; as far north as Lee, DeKalb, and Kane counties; and as far south as Coles and Edgar counties. Really? The narrative that accompanies the map states: "Western corn rootworms are causing signif icant damage to first-year corn in an expanding region of the central Midwest. University researchers have advised farmers to consider applying a soil insecticide when planting first-year corn in affected areas." The first sentence may or may not be true; whether or not the problem has expanded in range in Illinois has not been verified. And, although the second sentence is true, we have been a bit more conservative with our description of the "affected area."

In this day and age, when we in agricul ture are trying to convince the general public that we are good stewards, why would we want to revert to treating all acres of corn with soil insecticides "just in case?" From 1978 to 1990, the use of soil insecticides on corn in Illinois decreased from a bout 67% of the acres treated to about 34% of the acres treated. This reduction occurred primarily because producers learned that soil insect problems were infrequent in corn rotated annually with soybeans. We should be proud of that. Yes, the situation h as changed in east-central Illinois; and, no, we cannot predict with any accuracy in which fields the problem will occur. However, although many producers experienced some miserable problems with corn rootworms in 1995, the incidence and severity of the p roblem in 1996 were significantly less. So far as we know, the problem area has not "expanded" in Illinois.

DowElanco's ad does not demonstrate good product stewardship when it suggests "it pays to treat your first-year corn like all your corn." Eve n in corn planted after corn, research data indicate that probably only 50% of the acres have an economic level of rootworm damage annually, yet about 90% of the acres are treated. Although the problem with rootworms in corn after soybeans is nerve-wracki ng and makes producers uncomfortable, taking advantage of their fear of this problem is inappropriate. The attitude of treat it all and sort it out later is irresponsible.

Kevin Steffey and Mike Gray, Extension Entomology, (217)333-6652