Submitted to: Canadian Pest Management Research Reports
Publication Type: Research Notes
Publication Acceptance Date: 4/19/2005
Publication Date: 7/10/2006
Citation: Errampallid, D., Janisiewicz, W.J. 2006. Evaluation of biological control activity of Metschnikowia pulcherrima for control of blue mold on 'Empire' apples in cold storage, 2003-2004. Canadian Pest Management Research Reports 43:139-140. Interpretive Summary:
Technical Abstract: A yeast antagonist, Metschnikowia pulcherrima, was tested for efficacy against blue mold caused by Penicillium expansum on 'Empire' apples. The trial was conducted on commercially ripe apples. All fruits were stored in CA storage until used. Apples were disinfected in 10% household bleach (5% sodium hypochlorite) and 0.01% Tween 20 (Fisher Scientific) for four minutes and rinsed in reverse osmosis water for four minutes. After disinfection, apples were placed on plastic packing inserts (fruit master) contained in plastic boxes. The apples were punctured once with a nail-like probe (5 mm diam.) to a depth of 4 mm and were inoculated within 45 minutes of wounding with a 20 µl drop consisting of one of the three concentrations of M. pulcherrima with Penicillium expansum isolate PS-1R. Treated apples were incubated at 4ºC for three months. Apples in each of the experiments were evaluated for decay after the respective incubation periods. After decay evaluations following incubation at 4ºC, the fruits were moved to 20ºC, 85% RH and incubated for six days to determine the efficacy of the biocontrol agent on the shelf life of the fruit. The fruit were again evaluated for blue mold incidence. The data obtained was analyzed with a SigmaStat statistical package. The results indicate that the initial low decay incidence increased with time. After 28 days of incubation, 88% blue mold infection was observed in the inoculum only treatment, while the treatments with the combination of M. pulcherrima and the pathogen ranged between 0 to 61%, depending on antagonist/pathogen ratio. Better control was achieved with the lower concentrations of the pathogen inoculum. The combinations of M. pulcherrima and 1 x 10 4 conidia/ml of P. expansum resulted in the lowest incidence of blue mold. Two combinations, 1.6 x 10 7 CFU/ml of M. pulcherrima, and 1 x 10 4 and 5 x 10 4 conidia/ml of P. expansum, gave initially complete control of blue mold, but by day 86, all fruit had decay. Additional antagonist applications may be needed to achieve longer lasting control on this cultivar.