Box elder tree dropping leaves - Ask Extension
I have an old box elder tree that has been dropping leaves all summer. The leaf dropping has accelerated the past couple of weeks. It receives regular...
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Box elder tree dropping leaves #847266
Asked August 25, 2023, 11:56 AM EDT
I have an old box elder tree that has been dropping leaves all summer. The leaf dropping has accelerated the past couple of weeks. It receives regular watering. Any suggestions of what’s going on?
Larimer County Colorado
Expert Response
Hi Angel,
Welcome to the year of the Sensation boxelder! You're one of dozens that has reached out with concerns over their tree.
To be perfectly honest, we don't know what's causing the damage. There are several thoughts circulating among tree care professionals and diagnosticians. The first is that it could be a disease. We did send samples to the CSU Diagnostic Lab and they cultured out a disease, BUT it tends to not be something that causes long term harm. If it is a disease, it infected the tree way back in the spring when we had all the rain and cooler temperatures. So trying to "fix it" at this point is not an option.
Another potential cause could be ozone injury. Boxelder can be very sensitive to ozone levels, and our summer has had numerous days where the ozone quality has been high and potentially unhealthy to humans (like yesterday). Because these trees are from all different landscape sites, and in various stages of maturity, and have various cultural things, something environmental (like ozone) can be likely.
Going forward this fall, keep the tree healthy and watered as much as you're able. Water it in the fall and winter once or twice a month on warm days. As the leaves fall, rake them up and throw them in the trash (if it's a disease, this can help break the disease cycle).
The trees I've looked at have set their buds for next year, which is very promising. I think it was a "perfect storm" of conditions for 2023.
Please let me know if you have any questions!
Welcome to the year of the Sensation boxelder! You're one of dozens that has reached out with concerns over their tree.
To be perfectly honest, we don't know what's causing the damage. There are several thoughts circulating among tree care professionals and diagnosticians. The first is that it could be a disease. We did send samples to the CSU Diagnostic Lab and they cultured out a disease, BUT it tends to not be something that causes long term harm. If it is a disease, it infected the tree way back in the spring when we had all the rain and cooler temperatures. So trying to "fix it" at this point is not an option.
Another potential cause could be ozone injury. Boxelder can be very sensitive to ozone levels, and our summer has had numerous days where the ozone quality has been high and potentially unhealthy to humans (like yesterday). Because these trees are from all different landscape sites, and in various stages of maturity, and have various cultural things, something environmental (like ozone) can be likely.
Going forward this fall, keep the tree healthy and watered as much as you're able. Water it in the fall and winter once or twice a month on warm days. As the leaves fall, rake them up and throw them in the trash (if it's a disease, this can help break the disease cycle).
The trees I've looked at have set their buds for next year, which is very promising. I think it was a "perfect storm" of conditions for 2023.
Please let me know if you have any questions!
This is extremely helpful. Thank you very much!
