Section 18 for Coragen, for Corn Earworm, Sweet Corn

Eileen Cullen, Extension Entomologist

On July 23rd, the U.S. EPA approved a Section 18 request by the Wisconsin Department of Agriculture Trade and Consumer Protection (WI DATCP) and UW Madison Entomology Department for the use of the insecticide, Coragen (DuPont), in the state of Wisconsin. The Section 18 has been approved for use in Minnesota and Illinois, and is pending in other Midwest states. (The text of this article is reprinted from Dr. Bill Hutchison's July 11th MN Fruit & Vegetable IPM News article, - Vol. 5, No. 8 http://www.vegedge.umn.edu/MNFruit&VegNews/vol5/711Section18.htm and updated to meet the Wisconsin DATCP Coragen Section 18 announcement July 23rd, 2008).

A maximum of 30,500 sweet corn acres may be treated in Wisconsin. Use of Coragen on sweet corn is targeted for late-planted sweet corn that is historically susceptible to migrating Corn Earworm (CEW) moths that cause considerable damage to sweet corn ears. The Section 18 request was made due to increasing problems with pyrethroid resistance in corn earworm in Minnesota, small plot trials in Wisconsin, and the Midwest. In 2007 for example, percent control for all sizes of CEW larvae, for several locations in Minnesota and Wisconsin, averaged 35% using common pyrethroids (bifenthrin and lambda-cyhalothrin). In recent evaluations, Coragen has provided >90% control of CEW larvae in late-planted sweet corn. Improved control with Coragen (active ingredient Rynaxypry) is attributed to a unique mode of action at insect muscle tissue receptors with a high degree of mammalian safety.

Processing companies and fresh-market growers should check with their dealers to determine when the product will be available, final pricing, etc. Although we do not know actual costs for Coragen, it will be more expensive than the pyrethroids. Final use will depend on overall CEW pressure this year, previous problems with pyrethroids, or other insecticides at your location. Based on university trials the past 2 years, the 5 fl. oz. rate has worked well; however, a surfactant such as MSO must also be included (university trials have had good results with MSO at 0.5% v/v). Another consideration, with alternating Coragen with pyrethroids or other materials, is that Coragen should be used for the 1stand 2nd sprays, to ensure maximum CEW control and ear protection. Coragen is also effective on European corn borer (ECB). There is no need to tank-mix Coragen with pyrethroids or other insecticides.

Use requirements for the Section 18 include:
• Apply 3.5 – 7.5 fluid ounces (0.045 – 0.098 lb. ai / ac) of product per acre by ground or aerially.
• A maximum of 2 or 3 applications per season are allowed, depending on rate.
• A maximum of 15.4 fluid ounces (0.2 lb. ai / ac) of product is allowed per acre per season
• A 4 hour re-entry interval (REI) is required.
• The minimum interval between treatments and final application and harvest (PHI) is 1 day.
• All applicable directions, restrictions, and precautions on the EPA-registered label, as well as those outlined on the Section 18 Emergency Exemption use directions provided with the request, must be followed unless otherwise modified in the Section 18 authorization document.

Follow this link for the Section 18 Emergency Exemption Directions (pdf)  08WI07 final label.pdf