Natural Foods Merchandiser

Stalking corn worms the organic way

Produce Perspectives

The one vegetable that symbolizes summer, perhaps more than any other, is sweet corn—and for good reason. Not only does it taste great, but it is more nutritious than many vegetables, loaded as it is with vitamins.

But sweet corn has only been around since the mid-19th century. Sweet corn ripens earlier and has smaller cobs and sweeter, more tender kernels than Indian corn, which is why we eat one and feed the other to livestock.

The taste of organic sweet corn may be soured, however, by the occasional sighting of either of two little green worms that also find this summer treat delicious. For this reason, some stores choose to supplement their organic corn with conventionally grown. Others chop off the end of the corn and sell it open-ended on the stand, and some offer customers both trimmed and untrimmed.

The two worms, the European corn borer and the corn earworm, cause hundreds of millions of dollars in crop damage every year and organic and conventional growers struggle to control these pests. The corn earworm?s life begins in the corn silks where it then wiggles down to the tip of the ear?s sweet, starchy kernels. The corn borer, by far the worse of the two, enters through the side of the ear. They?re hard to eradicate because the protective cornhusk keeps them out of sight and shields them from most pesticide sprays.

Organic growers may release beneficial insects, like the trichogramma wasp, or use oil to coat the corn silks and smother the worms. Bacillus thuringiensis, a soil-borne bacterium raised in the lab, can be used to kill the worms if it is applied before they enter the ear. Bt is also invaluable to organic growers for controlling pests in other crops. It is safe to use and leaves no residue.

Conventional growers may use systemic pesticides to control the worms. Absorbed through the corn?s roots and circulated throughout the plant?s system, these pesticides work by delivering a dose of poison each time the worm takes a bite of corn. But what about when we take a bite?

Biotechnology has taken the concept of systemic pesticides and combined it with the biological capacity of Bt to produce corn that generates its own pesticide—systemic Bt. To the average person this may seem like a brilliant idea, but it is not without dire consequences. Genetically modified corn can?t shut off its Bt production. The Bt circulates throughout the entire plant long after the corn crop has been picked and even while the stalks are wilting and breaking down in the fields.

What are the effects on the soil organisms? This is unknown and untested. Bt also remains in pollen, which can drift across cornfields, causing problems for pollinators like monarch butterflies and other insects, as well as crop contamination. Constant access to Bt may also help the corn earworm and the corn borer develop resistance to the bacterium, leaving many organic growers without this valuable tool.

Even though it?s viewed as safe, Bt is a toxin and should be used sparingly so that it?s effective when growers need it. Organic growers place it on the corn silks, and it breaks down quickly in the sunlight, which is far different than the pesticide-producing crops that can pose a significant danger to America?s No. 1 crop. While the engineered corn is more often grown as an ingredient for processed food and feed than for eating fresh, both sweet and grain corn are being altered to resist insects and herbicides. Given this knowledge, your customers may not mind the sight of a worm in their corn.

Interestingly, according to 1995 research at Ohio State University, adult European corn borers laid 18 times as many eggs on conventional corn plants as they did on those that were organically grown. Another fact about corn: Its sugar can turn to starch in just a few hours, causing the flavor to dissipate. So once you decide what kind of corn to stock and how to present it, remember to always buy it as fresh as you can and keep it well chilled. Remind your customers to do the same and to eat it soon after bringing it home.

Mark Mulcahy runs an organic education and produce consulting firm. He can be reached at 707.939.8355 or [email protected]

Natural Foods Merchandiser volume XXVI/number 8/p. 34

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