Submitted to: Washington State Horticulture Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 1, 2003
Publication Date: December 1, 2003
Citation: Curry, E.A. 2003. Factors associated with lenticel breakdown in apples. Washington State Horticulture Association Proceedings. Available: http://postharvest.tfrec.wsu.edu/REP2003B.pdf. 9 pp. Interpretive Summary: Lenticel breakdown is a physiological disorder which has increased significantly on Fuji and Gala apples in the past 5-6 years. Before the packing process, there is little evidence of a problem; however, within a few days of packing, symptoms appear as dark brown pits in the fruit skin reducing marketable yield. This technical report to the fruit industry in the northwest is based on research over the past 3 years. Fifteen research plots in commercial orchards having a history of the disorder were established from the Canadian border to the Snake River, about 200 miles. First, components of the packing process were identified that aggravated the disorder. Second, fruit maturity was investigated to determine causal relationships. Third, preharvest factors were examined to determine common factors. Components of the packing process that aggravated the disorder were: 1) temperature of the dump tank water; 2) use of various soaps that removed natural wax; 3) waxing; and 4) combination of the above. Generally, fruit was being harvested too late based on starch clearing and flesh firmness. Lastly, fruit that was predisposed to this disorder had nutrient imbalances.
Technical Abstract: Many physiological disorders affect the surface of the fruit: stain, scald, pitting, russet, sunburn, discoloration, cracking and lenticel breakdown. The research deals with the fruit epidermis (that is, the cuticle and underlying 2-3 layers of non-storage cells), and how changes in both pre- and postharvest environment may alter this important tissue system. Although lenticel breakdown may occur on practically any apple variety, in the past 5 years it has been most prevalent on Fuji and Gala apples. The lenticels initially appear only slightly darkened, however, usually after packing, the cells underlying the lenticel itself begin to deteriorate and depressions appear. Ths disorder tends to increase the longer the fruit remain in storage. In the last year, a number of our research studies have shown certain factors are assocated with increased lenticel breakdown in Gala and Fuji apples; other experiments are in progress. This report presents preliminary findings related to the occurrence of this disorder in order to formulate and test hypotheses as to why some orchard sites are more susceptible than others.