So much for "homeland security." Your tax dollars at work.
Don't know about that area, but here in Arizona, crop dusters are all over the place. They operate from small strips, not air-fields. They can take-off/land in a couple hundred feet. Typically a cleared portion of land near the owner's home and, probably, crops (cotton). Without a good description, and/or tail number, tracking the plane would be hard.
I have known a couple crop duster pilots and consider them to be on the insane side of brave! {8^,