Extension engineer tells advantages of irrigation applications This is not your father's chemigation system. "We've seen tremendous improvements in chemigation technology over the past few years," says Texas Extension agricultural engineer Leon New.

New discussed some of the advantages of applying pesticides through an irrigation system at a recent Texas Agricultural Irrigation Association seminar in Amarillo.

He says advantages include:

- It's usually the most economical method.

- Farmers can make application on windy days.

- Applications are more timely than with aerial or ground sprays.

- Application techniques and equipment are greatly improved. Injection equipment is better than it used to be.

- Farmers may use less chemical.

The process, if used correctly, is environmentally sound.

About the only negatives with chemigation, New says, are the initial costs of equipment and the need for responsible applicators.

The latter would be the case with any form of pesticide spray system, however.

New says chemigation systems must include adequate environment and user safeguards. "Backflow prevention is essential," he says. "Farmers should consider installing a spring-loaded control instead of a flapper-type."

He says injection line check valves are also essential to keep the system from overflowing the chemical tank.

"Farmers want to add these safety devices even more than the EPA does," he says. "Farmers are the real environmentalists, and they don't want to spoil their water or soil."

He says farmers should select insecticides with low water insolubilitythat are oil soluble and labeled for chemigation. He also recommends systems with interchangeable heads to allow use on both high and low-profile crops.

"Corn farmers will want to place the nozzles low to take care of corn borers. Also, low spray heads are essential for mite control in corn. At 30 inches high, we get less control. We have to get the spray down where the mites are.

"And we have to have good pressure to assure adequate control. When farmers spray into a corn canopy, for instance, they have to penetrate a lot of foliage," he says.

New says essential safety devices include: check valves, air relief valve, low-pressure cut-off on the pivot, low-pressure drain, injection hose and an anti-backflow device.

"We can use chemigation efficiently," New says. "Pumps cost only about $3,500."