Efficacy of pre-harvest sprays to reduce rind pitting on Benny Valencia orange

Abstract

Post-harvest pitting is a non-chilling related physiological rind disorder that the reduces external quality of various cultivars. The primary cause of post-harvest rind pitting of Valencia orange fruit is unknown, however, incidence thereof is aggravated by a change in post-harvest relative humidity (RH) and rind water status. The incidence of this disorder is erratic due to a wide range of factors influencing fruit susceptibility. Various plant growth regulators were evaluated to reduce the incidence of pitting in Benny Valencia fruit. Pre-harvest foliar sprays were performed in orchards during the 2014-2015 seasons in a complete randomised block design (n=10). The application of 2,4-D (2,4-dichlorophenoxyacetic acid, 10 mg L-1) at 50% petal drop or after physiological fruit drop reduced the incidence of post-harvest rind pitting by 38% and 56%, respectively. Application of s-abscisic acid (s-ABA, 400 mg L_1) (Protone) and thiabendazole (TBZ, 4000 mg L-1) (ICA-TBZ) 14 days before harvest reduced the incidence of this disorder by 43% and 51%, respectively. No negative effects of the foliar sprays in the form of chemical burn or loss of fruit quality were recorded. These results offer a new direction in the possible control of the incidence of this post-harvest physiological disorder by reducing susceptibility prior to harvest.