Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2010
Publication Date: 5/1/2010
Citation: Karabulut, O.A., Smilanick, J.L., Crisosta, C.H., Palou, L. 2010. Control of brown rot of stone fruits by brief heated water immersion treatments. Crop Protection. 29:903-906. Interpretive Summary: Stone fruits, such as peaches and nectarines, rot after harvest, usually by the action of fungal mold pathogens. To stop these losses, fungicides are typically used, but immunity or resistance to their action develops rapidly in mold populations and buyers of ‘organic’ fruit prefer those that have not been treated with fungicides. In this work, we examined a simple technique of hot water immersion of the harvested fruit to manage this problem, and found it could partially manage rot on harvested stone fruit.
Technical Abstract: The effectiveness of brief (30 or 60 s) immersion in water at 24, 50, 55, 60, 65, or 70 ºC was evaluated for the control of brown rot, caused by Monilinia fructicola, on California-grown peaches, nectarines, and plums. Inoculated fruits were treated and either stored at 20 ºC for 5 days or at 0 ºC for 30 days followed by 5 days at 20 ºC to simulate commercial marketing conditions. Immersion in water at 55 ºC for 60 s or at 60 ºC for 30 or 60 s significantly reduced both decay incidence (percentage of inoculated wounds that developed infections) and severity (lesion size) among the remaining wounds that developed the disease. Water temperatures of 65 ºC or higher were phytotoxic and caused moderate to severe surface injuries. Immersion in water at 60 oC for 60 s was a particularly effective treatment for plums. Among plums stored after treatment at 20 ºC, this regime reduced the incidence of brown rot from more than 80% among control fruit to less than 2%. Among similarly stored nectarines, this treatment reduced the incidence of brown rot from 100 to less than 5%, or among nectarines kept in cold storage after treatment, from 73 to 28%. Performance of these relatively brief heated water treatments was comparable to that of longer (2-5 min) and lower temperature (45-50 ºC) treatments previously reported by other authors. Brief immersion in heated water can be an effective approach to manage postharvest brown rot of stone fruits, particularly when the use of fungicides is avoided.