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Title: Combination of 1-Methylcyclopropene and ethoxyquin to control superficial scald of 'Anjou' pears

Author
item Bai, Jinhe
item YIN, XINHUA - UNIV OF TENNESSEE
item Whitaker, Bruce
item DESCHUYTTER, KRISTI - OREGON STATE UNIV
item CHEN, PAUL - OREGON STATE UNIV

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2009
Publication Date: 7/8/2009
Citation: Bai, J., Yin, X., Whitaker, B.D., Deschuytter, K., Chen, P.M. 2009. Combination of 1-Methylcyclopropene and ethoxyquin to control superficial scald of 'Anjou' pears. HortTechnology. 19(3):521-525.

Interpretive Summary: Superficial scald (browning) of 'd'Anjou' pears usually develops after cold storage of ~ 3 months. Ethoxyquin has been used to control scald commercially. However, only a small amount of fruit can be treated within 7 days after harvest as recommended, and sometimes ethoxyquin causes phytotoxicity. Application of 1-methylcyclopropene (1-MCP) showed excellent scald control potential, with rapid and mass treatment feasible. However, fruit may lose normal ripening ability at a dosage necessary to control scald. In this investigation, 'd'Anjou' pears treated with 1-MCP immediately after harvest were stored at -1 °C for up to 5 months. After 1, 7, 30 or 60 days (d) of cold storage, part of the fruit were also treated with ethoxyquin and the remainder left untreated as non-ethoxyquin controls. The incidence of superficial scald, and the ripening ability of fruit were investigated after 3-, 4- and 5-month storages. All fruit ripened properly within 7 d shelf life at 20 °C regardless of treatments. Either 1-MCP treatment at harvest or ethoxyquin alone applied within 7 d adequately controlled scald for only 3 months. By contrast, 1-MCP + ethoxyquin controlled scald for 5 months, regardless of when ethoxyquin was applied from 1 to 60 d after the start of cold storage. Thus, a combination of 1-MCP, which is easily applied and does not influence ripening ability, and a delayed application (up to 60 days) of ethoxyquin, which is a low dosage that does not cause phytotoxicity on fruit, controlled scald sufficiently.

Technical Abstract: A 25 nL L-1 1-methylcyclopropene (1-MCP) application at 20 °C for 24 hours on the day of harvest plus an ethoxyquin drench at 1000 µL L-1 after 1, 7, 30 and 60 days (d) of cold storage controlled superficial scald of ‘d’Anjou’ pears stored in air at -1 °C for 5 months. 1-MCP alone, or ethoxyquin alone applied after 1 d or 7 d storage at -1 °C, adequately controlled scald for only 3 months, and delayed ethoxyquin application (30 or 60 d) did not control scald. The effects of 1-MCP and ethoxyquin on a-farnesene metabolism indicated that 1-MCP controlled scald by inhibiting a-farnesene synthesis and oxidation, whereas ethoxyquin worked only by inhibiting of a-farnesene oxidation.