TALMADGE, J. -- This case arises out of the use of pesticides in the Horse Heaven Hills and their alleged downwind fall-out in Badger Canyon, Benton County. The plaintiffs allege that pesticides drifted from the Hills down into the Canyon, onto their homes and farms, damaging their crops and plants. Defendant E.I. du Pont de Nemours & Co., Inc. ("DuPont") manufactured the pesticides in question (sulfonylurea herbicides named "Glean," "Harmony" and "Finesse"). Defendant Farmboy Spray Co., Inc. ("Farmboy") aerially sprayed them on wheat farms in the Horse Heaven Hills, at the behest of the other 27 defendants who own the farms ("Wheat Growers").