Agriculture Canada research | Bacterial disease can be devastating for apple, pear producers
Promising field trials have found that common microorganisms can reduce fire blight in apple and pear orchards by up to 50 percent.
However, it is uncertain when producers will benefit from the findings.
Agriculture Canada’s researchers have discovered that two common orchard microorganisms, a bacterium and a bacteriophage, provide a naturally occurring and environmentally friendly biopesticide that prevents and kills fire blight.
Early field trials have shown that the carrier and phage cocktail, which is sprayed on trees when they are flowering, is as effective as streptomycin in controlling fire blight.
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Streptomycin is an antibiotic registered for use in Canadian orchards and is the best defense against fire blight, said Antonet Svircev, who led the study.
Svircev, who has been studying fire blight since 1996, said the findings are a significant breakthrough.
“In my system, the friendly bacteria being used as a biological control agent also helps grow the phage, like a little incubator and carrier,” Svircev said.
“It’s a double edge system. The bacteria soft controls the fire blight bacteria, but then you have the phage that kills it.”
Streptomycin is effective at treating fire blight, but resistance can develop if it is overused, Svircev said.
“Most growers will not use biologicals alone — they’re considered soft. They don’t like to see a 50 percent efficacy rate. They like to see 100 percent efficacy,” Svircev said.
“So we’re recommending the use of biologicals along with a streptomycin program as part of an integrated pest management program so you can make the streptomycin last longer.”
Fire blight bacterium overwinters in the trunks, branches and cankers of host trees. In the spring, billions of bacteria seep out of the infected areas when the sugars start flowing. The infection starts once the bacteria come into contact with the open flowers.
It is difficult to calculate the financial damage fire blight causes because it is a sporadic disease. However, a fire blight epidemic in Michigan in 2000 caused more than $42 million in damages to producers, including the loss of 350,000 to 450,000 trees.
Svircev said larger scale field trials have to be run and approval from Health Canada obtained before producers get access to the microorganism. However, the Agriculture Canada scientists need a commercial partner to help with the trials and approval process.
“We need to find a partner who will say, ‘we will take a chance on you, work with you, and commercialize the product’ — that’s our biggest challenge,” Svircev said.
Biological agents that can manage fire blight are already approved for use in Canada.
