Because of climatic restrictions, fruit production is concentrated in a relatively few states in the U.S. Among the factors presenting increasing challenges to fruit growers is air pollution. In contrast to herbaceous annual agricultural crops, woody perennial fruit plants are subject to exposure to pollutants as acute episodes, season-long chronic exposures, as well as season-to-season chronic exposures. Therefore, air pollutants may influence the fruiting process at the time of flower initiation in year one or following fertilization, fruit set, fruit development and maturation stages in year two. An episode of acid rain during this period could influence productivity. The objective of the research in the laboratory is to examine the specific effects of acid rain on fruit production in grapes and apples.