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Pinpointing weeds from space
 By Steve Leer
Weeds don't grow in space. But those that shoot up from planet Earth may one day be controlled with technology of an otherworldly nature.
Purdue researchers are studying ways to pinpoint weed populations in crop fields using satellite images. From that research they hope to develop farm equipment capable of identifying specific weed species and spraying the unwanted vegetation with the appropriate herbicide.
"Some people call it Buck Rogers weed control," says Case Medlin, former Purdue Extension weed specialist.
Medlin's research involved field mapping. This past spring, his students planted weed and crop plots at Purdue's Agronomy Research Center near Montmorenci, Ind. Using aerial photography, images were captured of a soybean plot with no weeds, a plot with weeds only and a plot with a mixture of soybeans and weeds. From the photos, computer maps will be created to differentiate weeds from crops.
The maps could eventually lead to weed control computer programs. "This would allow farmers to locate weed patches, determine if the problem is at an economic threshold and then decide if it's worth treating," Medlin says.
Another Purdue researcher is tackling weed identification from the ground. Gaines Miles, professor of agricultural and biological engineering, has experimented with electronic sensor technology. His goal is to develop advanced sensors that can detect weeds even in a crop canopy. The weeds then could be treated individually.
By helping farmers apply herbicide only where it's needed, electronic weed detection could cut chemical use in fields by 50 percent, Miles says.
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