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Growers gain a Cornell-tested, environmentally friendlier strategy in their Integrated Pest Management program

The U.S. Environmental Protection Agency has granted a one-year approval for a novel plant protectant that has been tested at Cornell University as a seed coating for onions. This new treatment promises to help save New York's onion crop, providing that it can gain full approval for use beyond 1996.

New York onion growers may use Trigard on onion seed this growing season to combat the onion maggot, according to integrated pest management experts at Cornell's Agricultural Experiment Station in Geneva, N.Y.

"We can't afford to lose the onion crop here in New York for a number of reasons," said Charles J. Eckenrode, Cornell professor of entomology and researcher at the experiment station. "By providing the growers with safe, new control tactics, Cornell research indirectly assists others as well since this is a tremendously important crop to the state, it has many healthful qualities for consumers, and it means a lot to the local economies."

At 12,000 acres, onion ranks as one of New York's most valuable crops, with an annual value of between $50 and $75 million statewide. Grown in a highly organic, peat type of soil – known as muck – the average onion grower invests $2,500 to $3,000 into each acre before the onions are harvested. So, losing the battle with the onion maggot, with other pests or even to adverse weather spells doom for growers.

Using Trigard, provided by Ciba Plant Protection, of Greensboro, N.C., would help New York's onion growers in their Integrated Pest Management program, since it fits in with the principals of multi-strategy approaches more than some earlier efforts where there has been an over-reliance on pesticides.

For example, Eckenrode said that some earlier insecticides used to curb the onion maggot populations also significantly reduced the numbers of beneficial insects that eat onion maggot eggs and larvae in the field.

"Trigard is especially active against certain life stages of flies and their relatives, but only has weak activity against many other unrelated insect groups," he said. Research also found that cyromazine, the active ingredient in Trigard, shows no mutagenic or teratogenic activity in any laboratory tests. In fact, Eckenrode said that it is relatively safe to warm-blooded animals, while other onion field pesticides have a higher level of toxicity.

Cyromazine is not new to the agricultural market. The product is currently used to control the leafminer on celery and lettuce in Florida, Texas and Arizona. It is also used to control houseflies in commercial poultry houses in New York and other states.

"Onions are one of the toughest things to grow," said Thomas W. Walters, Cornell research associate in fruit and vegetable science. "And onion maggots in New York have had a long history of developing resistance to insecticides that are used on a continuous basis." For this reason, the researchers believe that they needed a new type of compound – such as Trigard – that the onion maggot has not been exposed to in the past, and it must be used in concert with other proven control strategies.

Significant agricultural economies are at stake as the onion maggot makes inroads toward pesticide resistance in New York and other states, according to the researchers.

In this case, the onion seed is coated with Trigard and some other ingredients at the seed house and thus becomes a tiny round pellet. In this way, small amounts of material are applied in a very precise way to the seed coat rather than in bands into the soil at planting. Three seed companies have permission to make the seed pellets: Asgrow, of Gonzales, Calif.; Incotec, of Salinas, Calif.; and Seed Dynamics, of Salinas, Calif.

Eckenrode explained that the research on the use of cryomazine started about five years ago on small field plots. Because Trigard was being used in other parts of the country on other vegetables, the researchers knew there would be minimal residue in the soil, particularly since such small amounts were being used.

"The first year of testing, we knew we had something and that it was likely to pay off for the onion growers later on," Eckenrode said. "Using Trigard on onions is a very effective IPM strategy. With IPM, you try to reduce pesticides and make the pesticides you do use more effective. Trigard is excellent IPM news since it reduces the onion maggot planting time toxicant per acre by 87 percent. It is also more selective than older soil insecticides, since it allows more beneficial insects and other life forms to survive, thus we gain more assistance from them in the battle to contain this serious onion pest. That's IPM to me."