- W van de Pypekamp
- QMS Agri Science, PO Box 416, Letsitele 0885, South Africa
- 2009
The effect of different pre-harvest strobilurin fungicides on post-harvest fruit decay was determined on HLH Mauritius in the Tzaneen area, Limpopo Province. Trees were sprayed with fungicides either as a single application 21 days before harvest, or as multiple applications, 63, 42 and 21 days before harvest. Evaluation of fruit revealed that Strobilurin X at 40 mt / 100 t water controlled post-harvest decay the best with 7% decay three days after removal from cold storage, compared to 18% decay on fruit in the untreated control treatment. Strobilurin X at 80 mt/ 100 t water and Strobilurin B also reduced post-harvest decay significantly, while Strobilurin A and Strobilurin A + Wetcit had no reduction in decay.
Summary:
- Treatments involved single and multiple foliar applications of several strobilurin formulations, applied either 21 days before harvest or in a sequence (63, 42, and 21 days before harvest).
- Strobilurin X (40 ml/100 l water) provided the best control, showing only 7% decay three days after removal from cold storage, compared to 18% for untreated control.
- Strobilurin X (80 ml/100 l water) and Strobilurin B also significantly reduced decay at the initial three-day evaluation.
- Strobilurin A (with or without Wetcit) did not reduce post-harvest decay; in some tests, decay was higher than other strobilurins.
- After five and seven days, no statistically significant differences in decay were observed between the treatments and the control, though Strobilurin X and B still showed numerically lower decay.
- A post-harvest prochloraz dip greatly reduced decay rates across all treatments, largely masking differences due to pre-harvest sprays.
- The study suggests pre-harvest Strobilurin X and B are effective for initial decay control, but optimal timing and combination with other treatments (like post-harvest dips) require further investigation.
- The timing of fungicide application appears critical for maximizing post-harvest disease control.
- Additional work is needed to determine ideal spray intervals and consider fungicide residues for best practice.