We've barely turned the corner on September, and already, the maple in my back yard is turning color and dropping leaves. I've noticed a couple other trees in my neighborhood doing the same thing.
Signs of an early fall? No. More likely a cry for help.
Most tree species start turning color around the third week of September in the Twin Cities, according to Travis McDonald, a certified arborist in Eden Prairie with Davey Tree (http://bit.ly/1hHmQtg)
If your tree is well ahead of schedule this year, it's probably a distress signal.
"Early fall color can be health-related," he said. "If trees are stressed, they're going to defoliate," especially at the crown.
Trees can become stressed for a variety of reasons:
1. Lack of water. Even though the Twin Cities is not currently experiencing drought conditions, that's no guarantee individual trees are getting enough moisture. "We've had downpours instead of nice, consistent rains," said McDonald. Urban trees, especially those planted in islands of turf grass, may not be getting much runoff.
The remedy: Keep the hose and sprinkler going well into fall. "Turf grass can go dormant, but trees still need watering up until freezing," McDonald said. That goes for evergreens as well as deciduous trees.
2. Root girdling. Maples are especially prone to this condition, in which roots wrap around the trunk and pinch off the flow of water and nutrients. "This can stress the canopy on hot days," McDonald said. Look at the base of the trunk, at the root flares. "If one is flared out and another is heading down, dig down to see if one of the roots is wrapping around and strangling the tree," he said.
The remedy: Cutting away the girdled root is a job best left to a professional. "If you can cut too much, you can kill the tree," McDonald said.
3. Soil compaction. The soil around established trees can become so compacted that it inhibits the uptake of minerals, "If mowing is taking place around the tree, soil compaction is likely," McDonald said.
The remedy: "Soil compaction is hard to correct," McDonald said. Amending the soil can help. So can "vertical mulching" using an air spade, to get more air into the soil.
To troubleshoot stressed-out trees, consult with a certified arborist, McDonald advised.
Now is a great time to fertilize trees, he added. A slow-release fertilizer, used in the fall, can encourage root-system growth that will strengthen the tree's canopy next spring.
What are you seeing on trees in your own yard and neighborhood?