Pre-harvest 'Tree Fresh' spray treatment reduces disease incidence and extends the harvesting season of 'TJC' mango grown in Sri Lanka

Phospholipase D (PLD) is a key enzyme involved in the initiation of membrane deterioration by catalyzing the hydrolysis of membrane phospholipids. While enhancing the fruit membrane stability, the inhibition of PLD activity does not affect other enzyme activity. The C6 aldehyde Hexanal, is known to be a potent inhibitor of PLD activity. Hexanal, containing formulations, are currently being tested as pre and postharvest applications to extend the shelf life of fruits. A 2% solution of such a formulation referred to as tree fresh formulation (TFF), containing 0.2% hexanal, ethanol, Tween 20 and other compounds was prepared and tested. The experimental trial included 3 treatments, i.e., a 3 times spray treatment, a 2 times spray treatment and an unsprayed control. Fruit bearing mango trees were sprayed at 60, 40 and 20 d before the scheduled date for commencement of the commercial harvesting of the fruits. The fruits retained on the tree after commercial harvesting date (100-120 d after fruit set for 'TJC' mango) were harvested and tested each week for marketability and quality retention over a period of 4 weeks. Percentage fruit retention on the tree was observed to be higher in the triple spray treatment of the Tree Fresh Formulation (70%) compared to the double spray (55%) and the control (35%) even after 4 weeks from the commercial harvesting date. The severity of anthracnose and stem end rot diseases were observed to be low with higher marketability in the triple spray treated mangoes (6%) compared to fruits from the double spray treatment (8%) and the controls (19%) after 4 weeks. Results from the trials indicated that the tree life of 'TJC' mango could be extended by 4 weeks by the TFF triple spray treatment with acceptable quality at harvest.