"Cotton Candy" Fiber Barrier Protects Crops From Pests

One day farmers might exchange pesticides for an industrial grade polymer that looks and acts like cotton candy as a major weapon against onion maggots, cabbage maggots, corn earworms and other agricultural pests. Michael P. Hoffmann, Cornell University professor of entomology and director of the university's New York State Integrated Pest Management program, and his colleagues have been testing nonwoven fiber barriers made of ethylene vinyl acetate, or EVA, as a bug-prevention device. The polymer, identical to the material used in hot-melt glue guns, can be extruded under pressure to form webs that cover plants and appear to ward off agricultural pests.

Says Hoffmann: "The best way to envision these barriers is to think of cotton candy just like you buy at the circus, except remove 99 percent of the fibers and what remains is a nonwoven multidimensional barrier that can be strategically placed to interfere with insect behavior."

Hoffmann will introduce this new pest management tool in his talk, "Novel Pest Management Tactics: Pushing the Envelope," at the 2002 New York State Vegetable Conference Feb. 13 at 10 a.m. in the Holiday Inn, 441 Electronics Parkway, Liverpool, N.Y.

Nonwoven fiber barriers hold considerable potential for the management of onion maggots and cabbage maggots, says Hoffmann. Without any pest controls in place, as much as 90 percent of a cabbage crop can be destroyed, and as much as 40 percent of untreated onions can be wiped out. Currently, onion and cabbage fields generally rely on insecticides at planting to control maggots. Long-term reliance on insecticides is problematic because of the continuing threat of the development of resistance to the chemicals. "The need for alternative control measures for both the cabbage maggot and the onion maggot is critical," says Hoffmann.

Onion maggots use their hook-shaped mouthparts to feed on young onions, ultimately killing the plant. The feeding also permits the entrance and spread of fungal and bacterial pathogens to onions. Cabbage maggots burrow into the plant's main roots so that the plant wilts and dies.

In Hoffmann's field-cage experiments, the scientists learned that placing EVA fibers around the base of onion plants significantly reduces the number of eggs laid by female onion maggots. EVA-treated plants had an average of 1.4 eggs per plant compared with an average of 10.4 eggs for untreated plants.

During a cabbage maggot field-cage experiment, the researchers applied EVA to young broccoli plants. While the polymer appeared to inhibit the leaves unfurling for a week or two, the leaves broke free of the barrier and were unaffected by the fiber mat, says Hoffmann.

The nonwoven fiber project is still in the early stages. Currently, the material is too expensive and impractical for large-scale agricultural use. "We started with EVA because the material and delivery technology let us produce an array of fiber types for testing the effects of fiber density, diameter and color, and permitted the addition of repellents, such as capsaicin from hot peppers," says Hoffmann.

"One day we hope to use fibers with proper characteristics for pest repellence and timed degradation so that the barriers remain intact only as long as necessary. The technology exists, and it's just a matter of pushing forward with more research and development," he says. These weblike barriers also hold considerable potential for several other insect pests, birds and possibly even deer.

Joining Hoffmann on the research was postdoctoral associate Thomas P. Kuhar, now assistant professor at Virginia Polytechnic Institute and State University; and Jeffrey Gardner, research support specialist in entomology, and Peter Schwartz, Department of Textiles and Engineering, Auburn University, Ala. Joel Baird, former Cornell researcher in entomology, contributed to the preliminary fiber studies.

Research funding came from a grant from the U.S. Department of Agriculture's Cooperative State, Research, Education and Extension Service (Pest Management Alternatives Program) and the Environmental Protection Agency (Pesticide Environmental Stewardship Program). Funding also came from Cornell Agricultural Experiment Station federal formula funds.