Microbial biocontrol for foliar blight (Monilinia and Botrytis) of lowbush blueberry and fruit rot (Phomopsis and Fusicoccum) of cranberry

Project code: MU03-PATH04

Project Lead

Jim Traquair - Agriculture and Agri-Food Canada

Objective

To assess the efficacy of Sporodex®, Mycostop®, Prestop®, and Actinovate® to control diseases of wild blueberry and cranberry and to identify improved, endemic strains for potential development as biocontrol agents

Summary of Results

Lowbush (wild) blueberries and cranberries are important, high-value crops in Atlantic Canada, particularly in Nova Scotia. Wild blueberry production and quality can be severely limited by Monilinia and Botryitis blights on leaves and blossoms. Cranberry yields, quality and post-harvest storage can be limited by Fusicoccum and Phomopsis fruit rots. These diseases are currently controlled in Nova Scotia by the careful use of chemical fungicides within integrated disease and pest management programs. However, the arsenal of chemical pesticides is limited. Availability of biological controls as alternatives to use of fungicides would reduce risks to human health and to the environment.

Several biopesticides registered in the United States and Canada but not for these particular crops and diseases, were evaluated in the laboratory, in the greenhouse and in the field for their efficacy in suppressing these blight and fruit rot problems. In addition, naturally occurring yeasts and bacteria isolated from blueberry leaves in the field were investigated for their potential as biological control agents against these diseases. Bioassays were developed to conduct these assessments, first involving detached leaves and blossoms, and eventually graduating to whole plant bioassays in the lab and in the greenhouse.

None of the microbial products reduced cranberry fruit rot, so attention was focused on evaluating microbial biocontrol products for blights of wild blueberry.

From the seven microbial agents tested (four commercial formulations and three native isolates), Serenade Max® (Bacillus subtilis QST713) was selected as the most efficacious biofungicide for Monilinia foliar and blossom blight of lowbush blueberry, with activity against Monilinia blight comparable to the standard chemical fungicide control (Topas) currently used by growers.

Serenade Max® is produced by AgraQuest Inc., in Davis California and is registered for use on blueberries in Canada and USA for similar disease problems. The expansion of the label to include the use against Monilinia diseases in lowbush blueberry is being followed up by the company. It is anticipated that this product will provide a valuable tool for the integrated management of Monilinia blight and mummy berry disease of wild blueberry, and will be particularly useful to organic growers.

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