Everyone knows by now that on-the-go, site-specific herbicide applicators like the Weed Seeker can help farmers cut costs significantly. Why then, researchers have asked, is it so unusual to find one in use on Mid-South farms?

UT agricultural engineer Henry Moody believes he knows. “Weed Seekers are configured to work with hooded sprayers, and a lot of people aren’t interested in hooded sprayers. It slows them down. Another is system cost. We don’t have many farmers in the Mid-South at this point who are willing to make an investment in the technology.”

Moody and other UT engineers are hoping to change grower attitudes toward on-the-go weed sensing and spraying by reducing the cost of the technology while adding a few new features, including weed population mapping and intermittent spraying over the row with over-the-top materials.

The Weed Seeker, developed in the mid-1990s by James Hanks, a USDA Agricultural Research Service agricultural engineer, is usually sold as part of a hooded sprayer set up to spray the middles of cotton.

Normally, the hoods will have three weed detection heads mounted underneath. As these sensors move across the ground, they “see” weeds, bare ground or stubble. If a sensor recognizes a weed present in the middle, a solenoid valve is tripped and the weed is sprayed.

“We are looking at ways to manufacture the equipment at less cost,” Moody said. “We’re also interested in developing sensors that can tell the difference between crop and non-crop plants.”

UT engineers also are cooperating with weed scientists at North Carolina State University to develop intermittent over-the-top sprays for the Weed Seeker.

NCS scientists have done a number of studies on spatial relationships among weeds, i.e., how weed patches tend to form and cluster in fields. The scientists found a very strong relationship between weeds in the middles and weeds in the row, according to Moody.

“If there is a weed present in the middle or against the row, the chances are high that there are weeds in the row. And if there are no weeds in the middle, chances are there are no weeds in the row.”

Armed with this information, UT agricultural engineers added drop nozzles above each row to spray over-the-top material. “We trigger the valves that run the drop nozzles off the adjacent weed detection heads,” Moody said. “So if a weed is detected on either side of the row, the drop nozzle is turned on and an over-the-top material is sprayed over the top of the row.”

UT engineers also added a computerized data logger that mounts on the sprayer, along with a GPS receiver to provide position information. “We can map where the weed detection system found weeds in the field. This allows us to document where the weeds are in the field,” said Moody.

“The idea is to not only study spatial relationships among weeds, but also look at relationships from year to year.”

e-mail: erobinson@primediabusiness.com