1a. Objectives (from AD-416):
Evaluate benefits and risks of using ozone to control postharvest decay of table grapes.
1b. Approach (from AD-416):
Fumigate with ozone under laboratory and commercial conditions to establish effective rates.
3. Progress Report:
Progress was made on objective 2B in the parent project. At the San Joaquin Valley Agricultural Sciences Center in Parlier in 2011, tests to evaluate the use of ozone fumigation to prolong the storage life of fresh grapes were conducted. Ozone is an allowed substance for use by ‘organic’ growers under the USDA National Organic Program. Application of ozone gas was shown to extend the storage life of table grapes. Under controlled conditions, the penetration of ozone into various kinds of commercial grape packaging was evaluated. This helped to identify for growers and packaging manufacturers the type of packaging best suited for use in storage rooms where ozone gas is used. Under environmental conditions that simulated the cold storage of table grapes, the rate of mortality of seven common decay fungi was determined in a low concentration (0.1 ppm) of ozone gas shown in prior work to prolong fruit storage life. Most of these fungi died completely within several weeks, while in cold air alone they survived several months. This work provides information to add a method to control decay losses in the table grape industry, which produced 99 million boxes worth approximately $1,400,000,000 in California alone in 2010. These results were presented to growers and packaging manufacturers in several informal meetings; a portion was included in a written progress report to the California Table Grape Commission submitted January 31, 2012 and two oral presentations (university seminars).