Organic Farming Research Foundation -- Home

Managing Insect Pests

Integrated caterpillar control in organic sweet corn

Funded Projects

Amherst, Massachusetts --
Over a three period, investigators evaluated an integrated strategy of direct silk oil and Bt applications for corn earworm (CEW) caterpillar control on ten organic farms throughout the northeast. As part of this project, a hand-held syringe pump applicator with a lightweight backpack tank, called the Zea-laterTM was developed for delivering oil by hand to each silk along the row. The Zea-laterTM reduced the labor requirement for the single oil application to 8-10 hours per acre, and is now available through Johnny’s Selected Seeds.

Image of Zea-later oil applicator
Zea-laterTM applicator being used to apply
0.5 ml of oil/Bt to silking corn

For more information about this project:

Project summary
(4 pp, 174K pdf file)

Investigator Ruth Hazzard's complete project reports, Integrated caterpillar control in organic sweet corn:
Years 2 and 3
(19 pp, 233K pdf) and
Year 1
(13 pp, 793K pdf)

Oil applications may result in slightly reduced ear length and tip fill, called cone-tip, as a result of oil interfering with kernel pollination. Application timing requires balancing the need for caterpillar control from beginning to end of the silking period with minimal physiological effects to the kernels at the corn ear tip, which can occur when oil is applied too early.

Among the key project results, it was determined that one 0.5 ml application of corn oil/Bt, on day 5 after first silk, provided adequate to control CEW throughout ear development. The oil and Bt treatments appeared to control CEW for at least 17 days, from silking through maturity. The best combination of effective insect control resulting in the highest rate of marketable ears with the least degree of cone-tip was achieved by application of oil + Bt suspension on day 7. Year-to-year variation in the environment would suggest an optimum timing range of application from days 6 to 8. Bt rates of 1/4 to 1 lb/ac provided best results.

Principal investigator:
Ruth Hazzard, University of Massachusetts, Department of Plant, Soil & Insect Sciences

Project locations and grower collaborators:
Rob Johanson, Rob Johanson, Goranson Farm, Dresden, ME; Jack Manix, Walker Farm, Putney, VT; Skip Paul, Stone Farm, Little Compton, RI; Andy Caruso, The Upper Forty, Cromwell, CT; Steve and Ray Mong, Applefield Farm, Stow, MA; Dan Kaplan, Brookfield Farm, Amherst, MA; Tom Harlow, Westminster Station VT; Doug Coldwell, Coolwater Farm, South Deerfield, MA; Sandy Williams, Williams Farm, Deerfield, MA; DeWitt Thompson, Full Bloom Farm, Sunderland, MA

Cooperating investigators:
Pamela Westgate - UMass Extension and Dept. of Entomology, Univ. of Massachusetts; Anne Carter - UMass Extension, Plant and Soil Science, University of Massachusetts; Brian Schultz - School of Natural Science, Hampshire College, Amherst, Eric Sideman - Maine Organic Farmers and Gardeners Association; John Buonocorsi, Dept. of Mathematics and Statistics, University of Massachusetts

Keywords: organic sweet corn; corn earworm; European corn borer; oil application; Bt; Massachusetts; Connecticut; Maine; Vermont; Rhode Island; OFRF

OFRF funding:
$29,337, awarded in spring 1999, fall 2000 and spring 2002

Project period:
1999 - 2002

Reported:
May 2004