Science: Wild Oats Unsown

Like crab grass in a suburban lawn, wild oats in a field of wheat are an insidious pest. The stubborn weed looks like wheat, grows like wheat, and is so closely related to wheat that neither cultivation nor common weed killers can hold it back without harming the wheat crop. But a couple of U.S. manufacturers have finally concocted the kind of agricultural magic that farmers have been seeking for centuries: a weed-killing chemical so selective that it can actually tell wild oats from wheat.

Stirred into the soil, Avadex (Monsanto Chemical Co.) kills wild oats just as seeds begin to sprout....