ARS | Publication request: IMPROVING BIOCONTROL USING ANTAGONIST MIXTURES WITH HEAT AND/OR SODIUM BICARBONATE TO CONTROL POSTHARVEST DECAY OF APPLE FRUIT

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 26, 2005
Publication Date: June 1, 2005
Citation: Conway, W.S., Leverentz, B., Janisiewicz, W.J., Saftner, R.A., Camp, M.J. 2005. Improving biocontrol using antagonist mixtures with heat and/or sodium bicarbonate to control postharvest decay of apple fruit. Postharvest Biology and Technology. 36:235-244

Interpretive Summary: Efforts to find alternatives to chemical control to reduce losses due to postharvest decays have been ongoing for some time. There has been an increasing demand by consumers to reduce residues on produce due to health and environmental concerns and many fungi are becoming more resistant to commonly used fungicides. Alternatives to chemical control, when used alone, are usually less effective than fungicides. To increase effectiveness, we combined three alternative control methods: biological control using yeasts alone and in mixtures, heat treatment, and sodium bicarbonate solutions. When combined, these treatments resulted in greater control of blue mold and bitter rot of apple than any of the treatments used 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 and then treated with various combinations of heat (38 degree C) for four days, 2% sodium bicarbonate, and two biocontrol agents alone or combined. The fruit were stored for four months at 1 degree C and then at 20 degree C for two weeks. Either heat or the antagonists reduced decay caused by C. acutatum, but a combination of the two was required to completely eliminate decay caused by this pathogen in most cases. Sodium bicarbonate alone or in combination with the antagonists had little effect on this pathogen. The antagonists alone reduced decay caused by P. expansum but tended to be more effective when combined. Sodium bicarbonate increased the effectiveness of decay control by each antagonist alone or in combination. All of the treatments that included heat virtually eliminated decay caused by this pathogen. The proper combination of alternative control measures can provide an effective strategy to reduce postharvest decay of apple fruit.