- SH Swart
- QMS Agri Science, PO Box 416, Letsitele 0885, South Africa
- 2009
Prochloraz and fludioxonil alone and in different combinations were evaluated, as dip treatments in fungicide solutions at ambient temperature (22°C) and heated (55°C), for short (30 sec) and long (5 min) exposure times, for their ability to reduce post-harvest decay of litchi fruit. Fruit were stored at 3 ± 1°C (RH > 85%) for 40 days to simulate export conditions and thereafter at 10 ± 2° C in order to evaluate disease development during shelf life. The percentage disease free fruit at 0, 4 and 8 days after removal from storage at 3 ± 1°C were determined. Results showed that fungicide mixtures, sometimes at concentrations as low as 50% of individual fungicides, were the most effective to reduce post-harvest decay. A mixture of 405 ppm prochloraz and 300 ppm fludioxonil gave the best results, especially when fungicide solutions were heated and fruit were dipped for 30 sec. In general dip treatments in heated fungicide solutions for 5 min was less effective. Pericarp browning remained a problem on fruit in all treatments.
Summary:
The study evaluated the effectiveness of prochloraz and fludioxonil fungicides, alone and in different combinations, as dip treatments at ambient (22°C) and heated (55°C) temperatures for 30 seconds and 5 minutes to control post-harvest decay in litchi fruit.
Litchi fruit were stored for 40 days at 3 ± 1°C and 85% relative humidity to simulate export conditions, then held at 10 ± 2°C to assess disease development during shelf life.
Mixtures of prochloraz and fludioxonil were more effective at reducing post-harvest decay than either fungicide alone, sometimes at concentrations as low as 50% of individual fungicide doses.
The best results were achieved with a mixture of 405 ppm prochloraz and 300 ppm fludioxonil, especially when fungicide solutions were heated and fruit dipped for 30 seconds.
Longer dip times (5 minutes) in heated fungicide solutions were generally less effective, with shorter 30-second dips preferred.
Fludioxonil alone at 300 ppm showed poor disease control in this trial, contrasting with some previous results.
Pericarp browning remained a significant issue across all treatments, indicating fungicides alone do not address this problem.
Adding a quaternary ammonium compound (Sporekill) to low-dose mixtures improved decay control significantly.
The diversity of pathogens affecting litchi means a broad-spectrum approach using fungicide mixtures is more effective.
Treatments to reduce pericarp browning and fruit dehydration are essential alongside fungicides for optimal post-harvest quality and shelf life.
The study supports the use of fungicide mixtures, particularly heated solutions with short dip times, as promising strategies to manage decay in litchi fruit.
Future research should explore combining fungicides with acid dips and coatings to address both decay and browning for commercial post-harvest handling.