|Mlikota Gabler, Franka|
Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2009
Publication Date: 10/21/2009
Citation: Mlikota Gabler, F., Mercier, J., Jimenez, J., Smilanick, J.L. 2009. Integration of continuous biofumigation with Muscodor albus with pre-cooling fumigation with ozone or sulfur dioxide to control postharvest gray mold of table grapes. Postharvest Biology and Technology. 55(2):78-84. Interpretive Summary: Fungal spoilage of table grapes during storage and marketing is a serious problem for grape producers worldwide, and the primary method to manage this problem is sulfur dioxide fumigation, which causes some injury to the fruit, is prohibited from use by organic growers, and it raises concerns about human and environmental safety. In this manuscript, we describe the integration of ozone fumigation with 'biological' fumigation with natural antifungal volatiles from the fungus Muscodor albus to control postharvest decay of table grapes. We showed these approaches, both acceptable to organic growers, significantly reduced postharvest losses, although their efficacy was inferior to sulfur dioxide.
Technical Abstract: Sulfur dioxide (SO2) fumigation controls postharvest decay of commercially stored table grapes. To develop an alternative to SO2, fumigation with up to 10,000 micro-l/l ozone (O3) for up to 2 h was applied to control postharvest gray mold caused by Botrytis cinerea. O3 was effective when grapes were inoculated up to 24 h before fumigation and incubated at 15C before treatments. The cluster rachis sustained minor injuries in some tests, but not berries. We evaluated an integrated treatment incorporating O3 fumigation during grape pre-cooling and continuous biofumigation during storage with in-package generators containing Muscodor albus, a fungus that produces volatiles lethal to many microorganisms. M. albus in a grain formulation survived O3 or SO2 initial fumigation, but SO2 reduced production of isobutyric acid, its main active ingredient. Gray mold prevalence was reduced among inoculated ‘Autumn Seedless’ grapes from 91.7 to 19.3% by 1 h fumigation with 5000 micro-l/l O3, and further reduced to 10.0% when O3 and M. albus were combined. Natural gray mold prevalence among organically grown ‘Thompson Seedless’ grapes after one month storage at 0.5C was 31.0, 9.7, 4.4, 3.4, or 1.1% after no treatment, O3 fumigation, M. albus biofumigation, combined O3 and M. albus treatment, or use of SO2 pads, respectively. Although inferior to SO2 treatment, O3 and M. albus controlled decay significantly.