Possible fungal infection on birch tree? - Ask Extension
Our 10 year old birch tree looks like it has Stem Spot.
Wondering how to treat it.
It is within 10 feet of our shallow well and concerned it might ...
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Possible fungal infection on birch tree? #880261
Asked August 05, 2024, 1:16 PM EDT
Our 10 year old birch tree looks like it has Stem Spot.
Wondering how to treat it.
It is within 10 feet of our shallow well and concerned it might be
contaminate with chemicals if we treat it.
Wondering if we could keep it over the winter for the birds if we need to take it down.
Does the fungus spread to our other trees? We have Maples, Pines and numerous oaks.
Thank you
Stearns County Minnesota
Expert Response
Stem spot is not a recognized birch disease but rather a description. The following websites give detailed birch disease descriptions. Compare what you are seeing with these. I suspect that you are dealing with canker rot.
1. https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/birch/index.html (Click on the trunk areas)
2. https://www.gardenia.net/disease/canker
1. https://apps.extension.umn.edu/garden/diagnose/plant/deciduous/birch/index.html (Click on the trunk areas)
2. https://www.gardenia.net/disease/canker
Is it OK to keep over winter without treating?
Can the fungus, Canker spread to nearby to Oak and Maple trees?
I don't want to use chemicals secondary to risk to our well.
Plan is to keep over winter if the fungus doesn't bother other trees and birds.
Can you advise me?
Thanks!
Mary D Hall
Since canker is caused by a number of different fungi, it is impossible to predict if it will infect your maple and oak. Those trees are susceptible to some cankers. As the second website above shows there are lots of cankers and it lists which trees are susceptible to which fungi. These organisms are wind blown so your other trees will likely get some of these fungi but they may or may be susceptible. See:
https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/canker-diseases/
If these are high value trees you can send a specimen to the Plant Disease Clinic for analysis as to which fungus is involved and whether the other trees are susceptible. See:
https://pdc.umn.edu/
The following article is quite technical but it gives some good diagrams on how pesticides can enter wells.
https://www.usgs.gov/special-topics/water-science-school/science/pesticides-groundwater
https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/canker-diseases/
If these are high value trees you can send a specimen to the Plant Disease Clinic for analysis as to which fungus is involved and whether the other trees are susceptible. See:
https://pdc.umn.edu/
The following article is quite technical but it gives some good diagrams on how pesticides can enter wells.
https://www.usgs.gov/special-topics/water-science-school/science/pesticides-groundwater
