Pre harvest Fruit Drop: A Severe Problem in Apple

Abstract

Preharvest fruit drop (PFD) is an important cause of fruit loss in apple industry and has been a recognized as severe problem in apple production for many years. Pre harvest fruit drop (PFD) in which fruits are shed from the tree before ripening phase prior to horticultural maturity can occur in several apple cultivars. The severity of drop is cultivar specific and cultivars have been categorized according to propensity to drop: less prone, intermediate and more prone. Studies in the early part of the 20th century were concerned with the physiology of fruit abscission as it occurred in the orchard. However, with the discovery of plant bio regulating chemicals (PBRs), the research priorities changed drastically from physiology of abscission to the efficacy of PGRs. The discovery of the abscission delaying properties of PBRs with auxin-like activity opened the new vistas for the development of chemical horticultural tools to reduce preharvest drop losses. Since the use of stop-drop materials became a common practice, research on preharvest apple fruit abscission has focused on development of better ways to use chemicals with commercial registrations. Unfortunately, chemicals used as horticultural tools have limited life spans and are primarily governed by regulatory and economic variables which are outside the control of apple growers.