Four small plains in formation repeatedly spraying over my home - no crop fields

I live in a neighborhood in North San Diego County Southern California. It is Friday September 13 2013. Four small planes flying in formation are spraying a chemical over my house just upwind. There are no crop fields nearby. They are at about 500 FT in the air - too high for crop dusters and there are no fields here. Its a rural neighborhood. They made three passes and then made two passes dumping a chemical from all four planes. The chemical trails were only about 500 yards long each time. Anybody ever hear of this?