Tiny Wasps Help Keep Sweet Corn Worm-free and Customers More Satisfied

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Ithaca, NY (June 7, 2006) - "Clean" sweet corn is not easy to grow, but organic and no- or low-spray growers are successfully dealing with potential pest infestations using tiny wasps so consumers won't find little worms when they husk their corn.

Five farm families are working with Abby Seaman, vegetable integrated pest management (IPM) extension educator of Cornell University's IPM Program, and Mike Hoffmann, Cornell professor of entomology, on a project funded by the farmer-led New York Farm Viability Institute to grow corn without chemical pesticides. The institute provides New York's farmers and growers with access to a network of production, business planning, marketing and agricultural and horticultural specialists that includes Cornell faculty and extension educators.

The farmers tested the use of tiny Trichogramma ostriniae wasps as natural predators that attack the eggs of the European corn borer and an all-season pest, the fall armyworm. Pheromone traps monitored moth activity as a gauge for timing three releases of the wasps. The growers evaluated spraying an insecticide approved for organic production and applications of a Bt-microbial insecticide (its bacteria produce toxins) mixed with soybean oil put directly on the corn silks as control methods for a late-season pest, the corn earworm.

Successful application of the natural pest controls to prevent a 25 percent loss of a sweet corn crop can mean as much as $750 per acre in sales for an average harvest of 1,000 dozen ears per acre and, an average selling price of $3 a dozen. In years of severe infestations when 75 percent of a crop could be lost, preventing that loss can mean as much as a $2,250 difference in sales per acre.

Worm-free corn also makes customers happier and more likely to purchase other farm products.

"We saw the most worm-free corn we've ever had, and our customers were quite pleased. That positive response impacted the sales of all of our farm market products," says Mike Thorpe of Thorpe's Organic Family Farm in East Aurora, N.Y., who participated in the project with his wife, Gayle.

"The control we had with the wasps in 2005 was better than with our past use of insecticides," says Dave Henderson, who grows unsprayed corn in Penn Yan, N.Y.

Henderson and Thorpe were two of five organic or no-spray growers providing a total of 36 acres of sweet corn for field trials.

In a customer survey at each farm, 91 percent of respondents were satisfied with the quality of the corn. All the farms market their corn directly to consumers.

"Control with wasps will naturally be more variable than the consistency achieved with insecticide application, but the results will most of the time satisfy customers that prefer direct market purchase of organic or no/low-spray products," Seaman says.

The wasps used in this project can be purchased from IPM Laboratories in Locke, N.Y.