Submitted to: Postharvest Biology and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/10/2004
Publication Date: 11/5/2004
Citation: Conway, W.S., Leverentz, B., Janisiewicz, W.J., Blodgett, A.B., Saftner, R.A., Camp, M.J. 2004. Integrating heat treatment, biocontrol and sodium bicarbonate to reduce postharvest decay of apple caused by colletotrichum acutatum and penicillium expansum. Postharvest Biology and Technology. 34:11-20. Interpretive Summary: Attempts to find alternatives to chemical control to reduce losses from postharvest decays have been ongoing for some time. Many fungi are becoming more resistant to commonly used fungicides and there is an increasing demand by consumers to reduce chemical residues on produce due to health and environmental concerns. Alternatives to chemical control, when used alone, are generally less effective than fungicides. To increase effectiveness, we combined three alternative control methods: heat treatment, biological control using yeast, and sodium bicarbonate solutions. The combined treatments resulted in greater control of bitter rot and blue mold of apple than any of the treatments alone. The apple industry may find that integrating heat treatment, biological control, and sodium bicarbonate may be a useful alternative to postharvest decay control using fungicides.
Technical Abstract: 'Golden Delicious' apples were wound inoculated with either Colletotrichum acutatum or Penicillium expansum then treated with heat (38 °C) for four days, sodium bicarbonate, and/or one of two heat tolerant biocontrol agents (yeasts). Following four months storage at 0°C, the apples were left at room temperature for two weeks. Populations of antagonists were stable throughout the experiment and were actually somewhat higher on the heated than the non-heated fruit. Each antagonist reduced decay caused by P. expansum, whereas heat or heat in combination with an antagonist eliminated decay. Either heat or the antagonists alone reduced decay caused by C. acutatum, but a combination of the two was required to eliminate decay caused by this pathogen. Adding sodium bicarbonate to the heated or antagonist-treated fruit had little effect on either pathogen, but when used alone, significantly decreased decay severity caused by P. expansum after 4 months at 0°C. The goal of this research is to combine alternative methods of control to provide an effective substitute for synthetic pesticides.