Pg. 63-65 Control of post-harvest diseases of litchi fruit with different fungicides and fungicide mixtures applied as dip treatments

Decay and browning of the pericarp is major factors affecting storage life and marketability of litchi fruit. Fumigation sulphur is the only chemical registered to control post-harvest decay on litchi fruit in South Africa. The increasing concern of consumers regarding sulphur residues in fruit and relatively high decay levels in spite of treatment, warrant investigation to find alternative measures to reduce decay of litchi fruit. Several fungicides and mixtures were evaluated as dip treatments in ambient or heated solutions for their ability to reduce post-harvest decay of litchi fruit. In this trial, heated solutions performed significantly better than solutions at ambient temperature when fungicides were evaluated alone, except for fludioxonil. Slightly better results were obtained for fungicide mixtures used at ambient temperature
compared to similar mixtures when heated. The best control of post-harvest decay after simulated export for 28 days and storage of fruit for 7 days at ambient temperature was obtained with prochloraz and fludioxonil mixtures. This was followed by fludioxonil applied alone at 300 ppm. Prochloraz and guazatine mixtures also gave significant reduction of post-harvest decay compared to the untreated control, guazatine and prochloraz applied alone. Concentrations of especially fludioxonil, alone and as part of a mixture, must still be optimised for treatment of litchi fruit.