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Title: EFFECT OF COMBINING MCP TREATMENT, HEAT TREATMENT, AND BIOCONTROL ON THE REDUCTION OF POSTHARVEST DECAY OF 'GOLDEN DELICIOUS' APPLES

Author
item Leverentz, Britta
item Conway, William
item Janisiewicz, Wojciech
item Saftner, Robert
item Camp, Mary

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2002
Publication Date: 3/1/2003
Citation: Leverentz, B., Conway, W.S., Janisiewicz, W.J., Saftner, R.A., Camp, M.J. 2002. Effect of combining mcp treatment, heat treatment, and biocontrol on the reduction of postharvest decay of 'golden delicious' apples Postharvest Biology and Technology 27 (2003) 221-233

Interpretive Summary: Attempts to find alternatives to chemical control to reduce losses from postharvest decay have been ongoing for some time. The search for control measures other than chemicals is increasingly important, because consumers demand less chemical residue on produce and many fungi are developing resistance to commonly used fungicides. However, alternatives to chemicals, when used alone, are usually less effective than fungicides. T develop a control strategy with increased effectiveness, we combined two non-fungicidal decay control methods: heat treatment and biological control using a yeast as the antagonist. The combined treatment resulted in greater control of blue mold decay of apple than either treatment alone. The apple industry may find that integrating biological control with heat treatment may be a useful alternative to postharvest decay control using fungicides.

Technical Abstract: 'Golden Delicious' apples were treated with 1-methylcyclopropene (MCP) or kept at room temperature (RT) for the duration of the MCP treatment. After the MCP treatment, they were wound inoculated with the pathogen Penicillium expansum or with P.e. and a heat tolerant yeast. After incubation at RT for up to 48 h, the apples were treated with heat at 38 C for 4 d, and/or moved dto cold storage for up to 5 mo. Heat had an eradicative effect, after the pathogen had incubated in the apple wounds for 6 or 12 h, resulting in the least amount of decay. The highest decay incidence occurred on the control that was inoculated with the pathogen and placed in cold storage. The least decay incidence and the smallest lesion diameter occurred on apples treated with a combination of the antagonist plus heat or heat alone. In general, MCP-treated apples had a higher lesion incidence, but similar lesion severity than non MCP-treated apples. Only in the combination treatment of heat plus the antagonist, between 6 and 24 h of pathogen incubation, was the lesion diameter slightly larger on MCP-treated fruit than on fruit not treated with MCP. This difference between the MCP-treated apples and non MCP-treated apples decreased during storage. Antagonist numbers in the apple wounds were stable or increased for all treatments. They were higher on MCP-treated apples than on non MCP-treated apples and they increased with longer incubation periods at RT after inoculation. Antagonist numbers on apples heat treated after inoculation were higher than those kept at RT. This was still true after 3 mo storage. The heat treatment had an eradicative effect, whereas the antagonist had a protective effect. The combination of these two control measures was complementary, and resulted in better decay control than either treatment alone.