Pg. 78-80 The effect of multiple phosphonate applications on post-harvest decay development of litchi fruit

The effect of two phosphonate formulations on post-harvest fruit decay, applied pre-harvest as foliar or as a soil drench application on cv. HML Mauritius, was determined. Programs were applied at three different pre-harvest intervals. After harvest fruit were subjected to simulated post-harvest export storage. Evaluation of fruit revealed that pre-harvest foliar or soil drench applications of Phytex or Brilliant significantly reduced post-harvest decay, compared to the untreated control. The initial evaluation done three days after removal from export simulated conditions, showed that foliar Phytex or Brilliant applications gave better control of post-harvest decay, compared to soil drench applications. However, evaluations done five and seven days after removal from export simulated conditions showed no significant differences between application methods regarding post-harvest decay control.

Summary:

• The study evaluated the effect of two phosphonate formulations (Phytex 200 SL and Brilliant 300 SL) applied pre-harvest as foliar sprays or soil drenches on post-harvest decay of litchi fruit cv. HML Mauritius.
• Applications were made at three different pre-harvest intervals, with fruit subjected to simulated export storage conditions post-harvest.
• Pre-harvest foliar or soil drench applications of both phosphonates significantly reduced post-harvest decay compared to untreated controls.
• Initial evaluation (3 days after cold storage) showed foliar phosphonate sprays controlled decay better than soil drenches.
• Evaluations at 5 and 7 days after storage showed no significant difference between foliar and soil drench methods in controlling decay.
• Post-harvest prochloraz dips reduced decay but masked the effects of pre-harvest phosphonate treatments.
• Multiple pre-harvest phosphonate applications provided good decay control, comparable to well-timed single applications.
• There was no significant difference in efficacy between the two phosphonate formulations.
• The timing of phosphonate application affected decay control, but the exact timing of infection requires further research.
• The trial was conducted in Tzaneen, Limpopo, South Africa, with a randomized block design and replicated treatments.
• The study suggests further investigation into the effect of phosphonates on sulphur-treated fruit, as different pathogens may be involved.
• Acknowledgments included support from Subtrop, the Litchi Growers Association of South Africa, product companies, and Tsunami Crop Care.