218 McKay 1992; Cameron and Dixon 1997). Besides maintenance of photosynthetic integrity, prevention of leaf abscission has been shown to be a significant contributor to growth under stress as leaves are the major photosynthetic organ responsible for carbo- hydrate production required for repair and functioning of dam- aged leaf tissue (Tyree et al. 1993). Likewise, leaf production rates are important variables influencing growth under environ- mental stresses (Pregitzer et al. 1990; Farrell et al. 1996). Signifi- cantly less leaf loss during the recovery period as stimulated by penconazole application enhanced total leaf area and subsequent photosynthetic area necessary for growth (Farrell et al. 1996). In- deed productivity as measured by total tree dry weight has been correlated with net photosynthetic rates (Ort and Boyer 1985). 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