Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 11, 1998
Publication Date: N/A
Interpretive Summary: Although fungicides can effectively control storage losses due to postharvest pathogens, consumer demand for pesticide free food may limit their future application. Therefore, alternatives to chemical control must be found. Previous research has shown that various postharvest treatments can be beneficial in maintaining apple fruit quality, but each, when used alone is not as effective as fungicides. To increase effectiveness, we combined three non-fungicidal decay control methods: biological control with a beneficial bacterium, calcium infiltration, and heat treatment. The combined treatment resulted in greater control of blue mold of apple than any of the treatments alone. The integrated strategy of heat treating fruit, followed by calcium infiltration and then treatment with a biocontrol agent may be a useful alternative for the apple industry postharvest decay control using fungicides.
'Gala' apples were treated after harvest with heat (air at 38 C for 4 d), pressure infiltrated with a 2 percent solution of calcium chloride, inoculated with the antagonist Pseudomonas syringae, or treated with a combination thereof to reduce postharvest decay caused by Penicillium expansum. No decay lesions developed on the fruit treated with heat after inoculation with P. expansum, nor any combination of P. expansum, antagonist or calcium (Ca) up to 6 months in storage at 1 C. A parallel lot of heat treated or nonheated fruit that were either infiltrated or non-infiltrated with Ca were stored up to 6 months. Then these fruit were inoculated with P. expansum alone or with the antagonist followed by P. expansum. Heat treatment had little residual effect on lesion development. Ca alone or in combination with the heat treatment, or the antagonist alone reduced lesion diameter by 62, 60, or 66 percent, respectively. Heat treatment combined with the antagonist reduced lesion diameter by 83 percent. Ca with the antagonist or a combination of heat, Ca and the antagonist treatment reduced lesion diameter by 94 and 96 percent, respectively. The integrated strategy of heat treating fruit, followed by Ca infiltration and then treatment with an antagonist may be a useful alternative to postharvest decay control using fungicides.