By Rebekah Ray

MISSISSIPPI STATE -- Wild radish, winter peas, wild mustard, vetch and curly dock may sound like ingredients of a savory green salad, but these wild host plants harbor bugs that are unsavory for Mississippi crops.

Identifying and controlling these plants can prevent early-season salad days for pests and save cotton producers money later in the season. Researchers with the Mississippi Agricultural and Forestry Experiment Stations and the U.S. Department of Agriculture are exploring the use of remote-sensing techniques to detect insects in broadleaf wild host plants and crops like cotton and soybeans. Cotton generated more than $483 million for the state's economy last year, and soybeans contributed more than $174 million.

Don Sudbrink is a postdoctoral researcher working with MAFES entomologist Aubrey Harris at the Delta Research and Extension Center in Stoneville.

"Remote-sensing technologies can provide quicker responses than customary manual scouting methods for determining the presence of cotton pests like plant bugs, mites and worms," Sudbrink said. "We're using remote-sensing technologies to detect wild host plant areas early in the season and also to detect pest infestations within cotton fields and crop maturity levels related to these pest infestations during the cropping season."

MAFES and USDA researchers are conducting a three-part evaluation using remote sensing for cotton insect pests in the Mississippi Delta, where tarnished plant bugs and other pests destroy more than 16,600 bales of cotton per year.

Early detection of pest infestations could reduce overall applications of pesticides using variable rate application technology, thus saving producers money. During noncropping periods, tarnish plant bugs feed and reproduce on broadleaf wild host plants. Remote-sensing technologies could help an area-wide program find and control them in early spring, reducing tarnish plant bugs populations before the cropping season begins.

Researchers sampled several sites for tarnish plant bugs on wild host plants and nonhost grasses at Stoneville and Tribbett. They collected developing tarnish plant bug populations from broadleaf wild host plants. Although tarnish plant bugs were not previously known to develop on grasses, this study revealed limited survival on ryegrass when the favored broadleaf host plants were destroyed.

Remote sensing and spectro-radiometry showed distinct differences between broadleaf hosts and nonhost grasses. This information will be useful in development of prescription maps for vegetation management practices.

Preliminary remote sensing revealed spider mite infestations in reddish "hot spot" patterns in cotton fields and discerned them from healthy and drought-stressed cotton in 1999. Nematode infested areas in the field could also be seen in the images based on very preliminary sample data. This information may be useful in the targeting of precision pesticide applications.

Researchers took remote-sensing data from cotton fields at Stoneville and Tribbett during the summer of 2000. The data revealed distinct areas of more vigorous crop growth in cotton fields that correlated with tarnish plant bug infestations. Lower plant bug infestations were found in the less vigorous plants that were shorter with smaller canopy coverage.

Researchers used this information to develop prescription spray maps of the fields that reduced pesticide applications by 30 to 50 percent. Other important pests also are being investigated in similar ongoing experiments.

For more information, contact: Dr. Aubrey Harris, (662) 686-9311