NEW HAMPTON - Crop dusters fly low, but they're no longer under the radar. Terrorists made sure of that.

The agricultural aviation industry was forever changed by the terrorist attacks against New York and Washington, D.C. Monday marks the five-year anniversary of jets slamming into the World Trade Center twin towers and the Pentagon.

Crop dusters have helped control weeds and insects from the air in Iowa since 1947. Watching planes swoop out of the sky and spray chemicals on corn and soybean fields was commonplace. No one gave it much thought - until planes were used to kill nearly 3,000 Americans.

Shortly after the attacks, the government grounded crop dusters on two occasions, fearing the planes could be used to deliver deadly chemical agents. People are also more paranoid than before, pilots say, occasionally calling law enforcement officials about low-flying planes near their property.

The days of just making sure the client is satisfied are gone. Now pilots have to worry about aircraft security, keeping chemicals safe and assuring the public their job won't harm them or their property. Instead of buying large quantities of chemicals, many crop dusters are ordering per job, so they're not responsible for long-term storage.

"I didn't like it, but I understood it," said Sam Klinkenborg, referring to the temporary grounding and changing times. "We used to tie them down and walk away hoping no one knew how to fly them. Security of aircraft has increased a lot - we keep them in hangers and locked up."

Klinkenborg owns Klinkenborg Aerial Spraying and Seeding in Parkersburg. However, like most crop dusters, he follows the work. Last Wednesday, he spent the afternoon spraying soybean fields near New Hampton infested with yield-robbing aphids.

The crop dusting business was already changing by 9/11, though the day's events drastically speeded up the process. Pilots say more city dwellers moving to acreages don't understand production agriculture. Crop dusting can be the fastest, most cost effective way to control pests and weeds.

But to the uninformed, they see a plane going between 110 to 150 mph about 8 to 12 feet above the ground spewing a fine mist,

"I got turned in last year by Iowa City for flying too low," said Glenn Speas, owner of Speas Aviation near Belle Plaine. "The sheriff had to come talk to me. He knew what I was doing, but I still had to shut down until we talked. It was just a hassle."

Times have changed so much, the Iowa Ag Aviation Association held its first-ever Ag Aviation Summit in Ankeny earlier this year. Pilots, airport officials and state and federal authorities gathered to discuss safety, security issues and public awareness, among other things.

To ease the public's concerns, conference attendees decided it was a good idea for crop dusters to tell airport managers and city officials spraying will be taking place in certain areas. Using the media get the word out would also be useful.

The National Ag Aviation Association has developed a security program specific to ag aviation. There are more than 190 licensed aerial applicators in the state, but only about 50 based here.

"I don't think the public has a big issue with aerial applicators," said Quentin Childs, director of the state ag aviation association. "Growers understand its normal activity. The issue is heightened when applicators are working near urban areas."

Besides terrorism fears, pilots have had to deal with several other new issues the past several years.

- Cell phone towers and wind turbines. The structures are being built more regularly. In the case of cell towers, if the structure is under 200 feet, Childs said it doesn't have to be registered, so pilots won't know they are there ahead of time.

- Organic agriculture. More farmers are growing organically that ever before, which means no chemicals. Preventing chemical drift is of the utmost importance.

- New acreage owners fear that chemicals will harm trees and grass. Childs said the chemicals used by most crop dusters are less harmful than what's under most people's kitchen sinks.

"Cell towers can spring up in just a few days. I almost hit one six years ago," Speas said.

Contact Matthew Wilde at (319) 291-1579 or matt.wilde@wcfcourier.com.