Crop duster pilot reports contact with truck exhaust while attempting to fly under wires at end of pass.

Narrative

Flying west to east on a spray pass at 10-20 FT AGL planning to go under wires along road at end of pass. Saw a truck approaching northbound. Had time to pass well in front of him; but at the last moment saw a truck directly ahead. Pulled up sharply; missing wires and truck except the left main tire sidewall bent the truck's exhaust. Company contacted owners to assure our company would pay for any repairs. Driver was asked if he wanted any medical attention which he denied; saying he would go back to work immediately. California Highway Patrol Officer said the driver saw the airplane coming; but he did not slow the truck down. This event could have been prevented by the pilot not trying to do such a perfect job with wires and a road on the end of the field. Drift is a huge problem in aerial application and flying under certain (but not all) wires avoids pulling up the spray into a drift situation. It also cuts down on the need for several head passes across the ends of fields with wires. After 30 years of doing this; the pilot just needs to go over rather than under in this situation. It wouldn't hurt if drivers who see a plane would just slow down a bit if possible; although that isn't really required or honestly expected. Will redouble and triple efforts to keep these operations as safe as possible.