Biocontrol of leaf curl in peach and mummy berry of lowbush blueberry using the bacterial biocontrol product Serenade Max (Bacillus subtilis)
Project Code: BPI07-030
James Traquair - Agriculture and Agri-Food Canada
To evaluate the efficacy of Serenade Max against leaf curl in peach and mummy berry disease of lowbush blueberry, value of this product to growers, and provide data for the tested crops to be included on the Canadian label of the product
Summary of Results
Leaf curl of peach and mummy berry of wild (lowbush) blueberry are two serious diseases that can cause significant yield losses and reduce the quality of these two soft fruits. The pathogens associated with these diseases persist over the winter and infect emerging buds in cool, wet spring weather.
Peach leaf curl (Taphrina deformans) causes severe defoliation, reduces fruit yield and weakens trees. Currently, peach leaf curl in temperate growing areas is controlled by dithiocarbamate and chlorothalonil fungicides. Mummy berry disease (Monilinia vaccinii-corymbosi) causes foliar blight. Monilinia diseases of blueberry are controlled by application of a propiconazole protectant fungicide.
The large acreage of peach and blueberry in Canada treated with conventional fungicides results in substantial environmental risks; affecting both residential (peach) and wild (blueberry) areas. Adding a biological component to integrated pest management strategies that are already in place for these crops would help reduce the risk to the environment and reduce the potential trade barriers that may result from the use of some products.
Serenade Max, (Bacillus subtilis QST 713), is a bacterial biocontrol currently registered in Canada and USA on many fruit and vegetable crops for a wide range of diseases. At the outset of this projects, this biocontrol agent was not yet registered for leaf curl of peach and mummy berry of blueberry in Canada. The goal of this project was to demonstrate the efficacy of Serenade Max in controlling leaf curl of peach and mummy berry of blueberry, generating data to support a label expansion for this product in Canada.
Field trials were conducted in commercial lowbush blueberry fields at Rawdon and Farmington, Nova Scotia, to evaluate the efficacy of Serenade Max. Serenade was applied at various concentrations either once or twice with the adjuvant Biotune. Leaf shoot and flower cluster infections were significantly reduced compared to the untreated control. Incidence of infected leaf shoots decreased linearly in response to increasing rates of Serenade and two applications were substantially more effective than a single application. Control of the disease was comparable to the industry standard.
Naturally-infested, ten-year-old peach trees (cultivar Loring) with a previous history of leaf curl disease problems in an AAFC Vineland orchard at Jordon Station, Ontario were treated with Serenade Max at the recommended rate and at double the recommended rate. A single application of Serenade Max at twice the label recommended dosage reduced peach leaf curl incidence to a levels similar to disease levels after standard fungicide treatment.
The data clearly showed that Serenade Max (Bacillus subtilis QST713) is effective in suppressing peach leaf curl and Monilinia blight of wild blueberry when used at about twice the label-recommended rate. The results also showed that the efficacy of Serenade MAX is better if disease potential is low and dosage and application frequencies are increased. Serenade Max fits the existing integrated pest management strategies for low bush blueberry and peach orchards and will be helpful for growers looking to increase national and international markets for fresh/frozen product. Timely applications of Serenade Max to wild blueberry and peach could replace the use of chemical pesticides and would benefit organic growers of these soft fruits.
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