Effect of a biological control fungicide agent (Pseudomonas syringae) and a chemical fungicide SCALA (pyrimethanil) on post harvest blue and gray mold of apple

Project code: MU03-PATH01

Project Lead

Deena Errampalli - Agriculture and Agri-Food Canada.

Objective

To investigate the use of a biological control agent (BioSave, Pseudomonas spp.), and a reduced- risk chemical fungicide (SCALA, pyrimethanil), for the control of blue mold and gray mold of apple.

Summary of Results

The control of post-harvest diseases of apples stored in many commercial operations in Canada depends on the application of fungicide after harvest as a dip or a drench. The extensive use of Mertect (thiabendazole, TBZ), until recently the only fungicide registered for this use, has resulted in the development of resistant strains of these storage rot pathogens, and this may be in part responsible for the increase in storage rots in Ontario and British Columbia over the last several years. Yield losses of as much as 20-30% can result from post harvest diseases in apple storage. To address this problem, pest control products with modes of action which differ from that of TBZ were assessed for efficacy in management of post harvest diseases of stored apples.

A reduced risk fungicide was tested for the control of blue mold and gray mold in Ontario and British Columbia. A preharvest treatment of SCALA® (active ingredient, Pyrimethanil) was tested for the control of blue mold and gray mold in Ontario on McIntosh and Empire cultivars and in BC on the cultivar Jonagold. In all of these tests, a significant reduction in blue mold and gray mold was observed in the apples treated with SCALA® as compared to the untreated controls. This preharvest use of the reduced risk fungicide a full two weeks prior to harvest has the benefit of reducing fungicide residues on apples while at the same time protecting the apples from diseases.

BioSave® (Pseudomonas syringae), a biological control agent was also evaluated for the control of post harvest diseases of apples, and was found to be efficacious as a protectant treatment against blue mold and gray mold of apple. By taking advantage of the natural relationship between the bacterial biological agent and fungal pathogens, the diseases can be controlled and in-storage damage to the crop can be reduced.

The data generated through the investigations was provided to the respective companies to help in the registration of SCALA®, a reduced risk fungicide, and BioSave®, a biological control agent for the control of post harvest diseases on apples. The successful development of post harvest disease control strategies for stored apples will provide an alternative to TBZ and an economic benefit to the producers while protecting human health and the environment.

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