I have struggled with apple trees. I was able to determine last year that I had 3 trees with fire blight and I think they also had apple scab. I remov...
Knowledgebase
Fireblight and apple scab #860263
Asked March 01, 2024, 4:38 PM EST
I have struggled with apple trees. I was able to determine last year that I had 3 trees with fire blight and I think they also had apple scab. I removed the branches with the dead leaves and about 2 weeks ago pruned the trees and dipped my pruning shears in Pine Sol after pruning each branch. I sprayed the trees last fall with Neem oil and again a couple days after I pruned them recently. I am now looking at what and when I should be doing next. From reading it appears that streptomycin, oxytetracycline (for fire blight) and a copper fungicide or phosphate fungicide (for apple scab). My question is what product would you recommend for the fire blight and what product for the apple scab? Is there one product that can be used to cover both problems? If not, can the two products you recommend be combined and sprayed together? With the warm weather we are having I am thinking I may need to be spraying them sometime in March. Thank you for any help you can give me. Apple trees are certainly a challenge to raise. You add the impact of deer, rabbits and mice and I am almost ready to give up
Carver CountyMinnesota
Expert Response
These web pages may be helpful. Extension Master Gardeners cannot recommend products by brand names. extension.psu.edu/2023-disease-update-scout-for-fire-blight-and-apple-scab-infections blogs.cornell.edu/applevarietydatabase/fact-sheet-fire-blight/ extension.umn.edu/plant-diseases/fire-blight I will also ask that your question be reassigned to someone with more knowledge of apple trees
They are a variety of different trees as I planted them and ran over one, deer ruined a few and mice chewed the bark off and killed a couple. I planted Honeycrisp, Zestar, and Haroldson. I have planted 2 trees a year for the last 10 years and have about 12 still living. The oldest ones are the ones with the fireblight. It went too long before I diagnosed what it was so I had to cut the trees way back to try and save them. They are about 3 inches in diameter. A few younger trees under 1 inch in diameter had a few signs of it last year and I pruned off the affected branches. I planted a couple chestnut crabs last year because they found they are not susceptible to fire blight. I also have a few trees with no evidence of any fireblight. I am going to plant a couple more trees this year and I want to plant those trees not impacted as much by fire blight but we prefer the sweeter tasting apples like honey crisp and first kiss etc. We like the chestnut crabs so may plant more of these. I have some photos I took last summer that I am including. The first photo shows the oldest and largest tree that has the worst fire blight. photos also show the fire blight, holes in the leaves from insects and take a look at the apples and maybe you can tell me if this is apple scab or what it is?.
As you can see in my previous email I sprayed the trees for the first time last fall with neem oil, pruned them a couple weeks ago and sprayed them with neem oil. With the warmer weather I am thinking about spraying them with a copper fungicide or a streptomycin or both. Considering all the things I encountered the last few years, I am trying to come up with a plan that will produce good looking apples ( I have never had any yet) and I am looking for input from anyone who has had experience with apple trees. What are your thoughts on putting composted/dry cow manure around the diameter of the tree a few inches from the trunk
Haralson is resistant to fireblight, and Zestar and Honeycrisp are moderately resistant. Pesticides are not usually recommended for treatment of fireblight, which usually enters the tree from wounds following out-of-season pruning or more commonly, damage from a hailstorm. The best thing to do is watch for any shepherd's crook drooping with brown leaves at the end of branches and immediately prune those branches back eight inches to a foot below the infection.
Once fireblight has reached the point where cankers are showing on the trunk, the best thing to do is to remove the plant. You'll see photos here:
Honeycrisp and Haralson are resistant to apple scab, Zestar isn't. However in healthy, well-maintained trees scab is usually a nuisance, showing up every few years. The best way to prevent scab is to prune trees so that they have plenty of air circulating in the canopy and to rake up scab-infected leaves in the fall.
I can't enlarge your photo, but this doesn't look like apple scab. It looks like leaf browning after physical damage like hail.
Should you choose to use chemicals for either of these issues, our recommendation is to follow the instructions on the label.
You could mulch the trees with well-rotted manure compost. There should be no ammonia smell -- it should be several years old -- and it should be several inches away from the trunks of the trees. Putting mulch against the bark can lead to rot and insect problems.
