Second Year Recovery of Hedgerow Walnuts from Sustained Deficit Irrigation

Hedgerow walnuts (cv. Chico) that were irrigated at 33 and 66% ETc from 1986-88 suffered marketable nut yield reductions of 32 and 50%. Upon returning these trees to full irrigation in 1989, tree growth and.water relations immediately recovered but yields were little changed. Harvest yields completely recovered this year (after two years of full irrigation). This indicates that hedgerow walnuts have the potential for rapid recovery from lengthy periods of water deficits. This fast production recovery from severe water stress was possible due to the absence of stress-induced disease or insect pressures. It must be emphasized that the absence of the secondary stress pressures of disease or insects is cultivar and site dependent. "Chico" is more tolerant of heat and water stress-related problems than other cultivars. Trunk diseases such as deep bark canker that occur in many water stressed orchards were not evident in this study. . OBJECTIVES To evaluate hedgerow walnut tree performance in the second season after returning to full irrigation following three years of sustained deficit irrigation.