Garden Help Desk: Time to say goodbye to sickly, bug-infested willow
I have a willow that has a disease that makes it smell bad and runs a sticky sap. It also has a white foam in areas. I used diluted bleach spray on it, which helped, but not sure if I can save it. It’s beautiful but losing large limbs each year. It also has borers that leave sawdust. I’m thinking I may have to remove it. Do you think I could save it?
You’ve described two different problems that you’ve seen with your tree. We’ll take a look at those today, and then I’ll describe a third problem with your tree that you may not be aware of.
First, your description of the foul-smelling foam and dripping sounds like the tree may have bacterial wetwood, aka slime flux or alcohol flux. For many trees, bacterial wetwood is a cosmetic issue, but sometimes the infection does affect the health of the tree. This disease is common on elm and willow but also affects many other tree species. The bacteria enter trees through small wounds, so preventing injury is an important part of preventing the disease.
Keep a wide grass-free area around the trunk to protect your trees from mower and trimmer injury. A wide tree ring with mulch also eliminates the problem of dead vegetation where the oozing drips from the tree. Shade trees need little, if any, pruning except to direct proper growth when young or to correct occasional problems. But if you must do any pruning, prune the tree properly and disinfect your pruning tools afterward to avoid transferring bacteria to other trees.
Give the tree good care by watering deeply, but not more than once a week during the summer and less often in the spring and fall. If your trees are in the lawn or must be watered with the lawn, water deeply but as infrequently as the lawn will tolerate (ideally not more than twice a week during the summer) to reduce the risk of infection in other trees.
The second problem with the tree is the borer damage. You’re seeing sawdust, which means borers are causing damage that weakens and kills branches. Borer damage can also lead to cracking and bark peeling on the trunk. Borer damage can’t be undone, it must be prevented.
With good tree care to promote its vigor, we can sometimes coax a few more years out of a declining tree. Other times, we need to look at a bigger picture to make sure it isn’t time to say goodbye to a tree. Here are some signs that it’s probably time to say goodbye to your tree:
- This tree has been losing large branches. Ongoing, smaller branch dieback is a sign that something is wrong with a tree. The loss of large branches is a sign that the problem is serious. Once a tree shows clear signs of trouble like this, it is too late to reverse the decline.
- Your tree is close to a walkway and street. Being close to a street, driveway or west-facing wall can be very stressful for trees. A tree in a location like that may be exposed to significant bounce-back heat, road salt, limited root space, higher air pollution levels and many other potential stressors. Not many tree species can tolerate conditions like these, and homeowners don’t always consider that when choosing trees for their landscape. Stressful conditions like this also make trees more susceptible to insect and disease problems.
- Your tree is old and unstable. Every tree species has a normal life span. Some species, like your willow, aren’t very long lived, especially when the conditions are stressful, and you could consider your tree to be the senior citizen of your landscape.
I don’t think it’s in your best interest to try to save your tree. With the branch loss, the borers, the wetwood and the age of the tree, you’d be fighting a losing battle. There is another reason to say goodbye to your tree, though. Your tree could be a high-risk tree.
When a tree is dropping large branches and is next to home, a sidewalk or street where parked cars could be damaged and pedestrians could be injured, or is near a picnic area, play area or any other frequently used activity area where damage or injury could occur when a branch fails again, it’s time to say goodbye to that tree.