- SH Swart and W van de Pypekamp
- QMS Agri Science, PO Box 416, Letsitele 0885, South Africa E-mail: willemv@agriscience.co.za
- 2008
Litchi fruit were dipped in solutions of prochloraz, fludioxonil, guazatine, Sporekill or Des-O-Germ, alone and in combinations, in order to reduce post-harvest decay. Disease pressure due to natural infection was low in this trial. Results showed that mixtures were more effective than individual fungicides applied as dip treatments. Concentrations of individual fungicides could be lowered when applied as mixtures, with enhanced efficacy. Post-harvest decay was mostly caused by Alternaria, Botryodiplodia, and Pestalotiopsis spp. Penicillium spp. was noticeably absent during this trial.
Summary:
The study evaluated post-harvest dip treatments of fungicides and fungicide mixtures to control decay in litchi fruit (cv. Mauritius) as alternatives to sulphur dioxide fumigation.
Fungicides tested included prochloraz, fludioxonil, guazatine, Sporekill, and Des-O-Germ, applied alone and in mixtures at ambient temperature.
Litchis were dipped for 30 seconds, dried, then stored under simulated export conditions (31°C, 85% RH for 40 days) followed by incubation at 10°C for 10 days to evaluate decay.
Most post-harvest decay was caused by Alternaria, Botryodiplodia, and Pestalotiopsis species; Penicillium spp. was notably absent.
Fungicide mixtures were more effective than single fungicides, allowing lower concentrations with improved efficacy.
Combinations of prochloraz + fludioxonil, prochloraz + fludioxonil + guazatine, and prochloraz + Sporekill resulted in zero decay after storage and incubation.
Prochloraz and fludioxonil alone at higher concentrations also gave good decay control.
Guazatine alone at tested concentrations was less effective. Sporekill and Des-O-Germ alone had limited efficacy.
The percentage of decay on untreated control was relatively low (~18.5%) due to low disease pressure during the trial season.
The study supports fungicide mixtures as effective for controlling a broad spectrum of post-harvest fungal pathogens in litchi.
Authors propose further semi-commercial scale trials in different regions with varying disease pressures to develop alternatives to sulphur fumigation.
The absence of Penicillium mould on fruit not treated with sulphur suggests this mould is linked mostly to sulphur fumigation treatments.
The research was supported by the South African Litchi Growers Association.