Q. I enjoyed reading your columns recently on grass fungus. They made me want to ask about sycamore trees. I have a couple out front that are about 10 years old. They grew well for a while and now they appear ‘thin’ in the canopy or just not healthy. Any ideas on what I can do for their health? – R.A., Albuquerque
The reason I ask is that if you’ve chosen to treat a lawn with a fertilizer that contains any sort of weed killer, the sycamores could have, inadvertently, picked up some of the weed killer properties and effectively maimed themselves. So on that note, NEVER apply a fertilizer containing weed killer on a lawn that has trees growing in or near it.
I know that sycamores are prone to a fungal disease called anthracnose. This fungal disease can make a tree look haggard. It’s recommended spraying in the spring with an old reliable fungicide called Bordeaux mix. But that’s applied just at bud break, again in the springtime.
This time of year, I would recommend keeping any leaves that drop raked up and disposed of. You don’t want any of the leaves to stay on the ground, allowing the fungus a comfy place to overwinter.
As soon as leaf drop is completed for this season, I suggest a spraying of dormant oil. Bugs, bug eggs and fungal spores can be prevented with a thorough spraying with a dormant oil spraying at least twice during the dormant season. Then with the Bordeaux spray in the spring the trees can be well protected for next year.
Next, I’m going to use the term decline. It sounds like the trees are in a state of decline. Now, that symptom isn’t directed to a specific bug or disease, but more to its surroundings. Perhaps something changed in their world.
Over time, a number of stressors have acted on the trees and now you’re noticing the effects. The sycamores might be mismatched to their sites; meaning a tree that grows so large is planted and expected to grow in a confined or too heated of a space. Has the soil been compacted by vehicles parking too close? Was a concrete path or patio poured anywhere underneath or surrounding them? Did you “rock-scape,” placing plastic sheeting beneath the rocks ? Were the trunks of the sycamores damaged by string trimmers when landscape maintenance was done?
There can be so many causes that cause a tree to decline, and I haven’t even mentioned water or fertilizer. So if you can address any cultural causes, and in turn fix them, there is hope for the health of the sycamore trees. You need to be honest with yourself and investigate what could be causing the decline of your trees.
For now make sure any leaves are raked up and disposed of; apply a root stimulator fertilizer; continue to water even during the dormant months; apply a dormant oil; make sure there is no plastic sheeting anywhere under the trees; don’t park under them and compact the soil; and tell the trees through your actions that you do truly care for them and in kind, if they aren’t too far gone, they’ll show you.
Hummingbirds know what’s going on season-wise, so please don’t worry that by leaving the feeders up you’ll be encouraging them to stay. Instinct has alerted them it’s time to migrate. There might be an occasional addled bird that chooses to stay, but most are in the process of heading south.
Keep the feeders clean and make sure the nectar is kept fresh so the travelers have a clean diner to stop at.
Happy Diggin’ In.
Tracey Fitzgibbon is a certified nurseryman. Send garden-related questions to Digging In, Albuquerque Journal, 7777 Jefferson NE, Albuquerque, NM 87109, or to firstname.lastname@example.org.