What is the best spray for fire blight?

Asked May 9, 2014, 8:56 AM EDT

I was wondering what the best spray for fire blight would be. I am planting 'Honeycrisp' and 'Sweet Sixteen' apple trees. I was thinking of Liquid Copper. Will the trees tolerate it, and if so, what brand would be the best for these varieties of trees? Is there anything else you would recommend to an amateur for this project?

Lake of the Woods County Minnesota

3 Responses

No control for fire blight is needed unless there is evidence the disease is present. The following excerpt from a University of Minnesota bulletin answers your question:

"Pesticides are typically not necessary to control fire blight in Minnesota. In trees where fire blight has been a problem in past years, a dormant spray of a copper-containing product can be applied to reduce new infections. Copper should be sprayed in spring between silver tip (when buds are just beginning to swell) and ½ inch green tip (when buds have opened and ½ inch of green leaf tissue is visible). Spray coverage should be more than just a mist, leaving a visible residue on the branches. This coating will kill the fire blight bacteria as they emerge from branch cankers and stop them from starting new infections. Copper sprayed later in the spring can be very harmful to foliage and fruit, so do not spray copper after ½ inch green tip.

"Although several sprays exist that can be used to stop the fire blight bacteria from starting a new infection, these sprays are unnecessary in trees that do not have a history of fire blight infection. In Minnesota, sprays are only necessary where fire blight has been a problem in the past, susceptible cultivars are being grown and weather is wet and warm (above 60°F) during bloom. Sprays are only applied during blossom."

Go here to read the complete bulletin: Fire Blight.


On the fire blight question you were so nice to answer for me, the place where I am going to plant the trees is about a quarter mile away from where I have planted trees before that have gotten fire blight. Do you think I should treat them for fire blight when it's that close, or should I be OK and just keep a close eye on them? Thank you for your expertise.

You should be OK. Just keep an eye on them.