Homegrown: Nov. 19, 2011
We have a large 45-year-old Japanese Pagoda tree in our front lawn. For several years, the tree has dripped sap from a location where a large branch was cut away. The sap has burned a hole 2 feet in diameter in the grass. There are a couple of other locations on the tree where sap drips at the site were larger branches were removed. Is there a way to seal the branch removal site from dripping sap?
It sounds like your tree has a bacterial disease called wetwood.
It’s actually a pretty common occurrence here in the Grand Valley in cottonwoods and elms but it also occurs in a wide variety of other trees.
The disease ferments the wood of the tree. In essence, it’s making “pagoda tree wine.”
The disease is characterized by a wet patch of bark or sap bleeding down the trunk. The ooze can be bubbly sometimes, but not always.
The ooze often smells sour or like stale beer. It often attracts insects, but they’re not hurting the tree, they’re feeding on the goo leaking from the tree.
It’s also pretty common for the ooze that runs down to the ground to kill the lawn.
The disease needs a wound to enter the plant. Most often (as it is in your tree), the infection starts in a pruning wound, but it also can occur at a branch junction since there are often minuscule cracks that occur as the branch moves in a strong wind.
Wetwood is very common. I’d guess that most, if not all of the older cottonwoods and elms in the valley have it. This is also a funny kind of disease in that a healthy and strong tree can coexist with the disease for years if not decades.
The disease sometimes kind of fades in and out of the picture. It bleeds this year, but not next. Then it bleeds for a couple of years, then doesn’t for some more. The disease is never really gone, it’s just sort of goes into hiding.
There really isn’t anything to do directly for the disease. The bacteria extend into the heart of the tree, and we can’t get chemicals in to kill it there. About the only thing you can do is to take good of care of the tree.
Make sure that the tree is watered deeply, but infrequently. Control any insect problems that crop up. Avoid preventable stresses such as physical damage to the roots or trunk. As long as the tree is healthy and happy, it will usually live with the disease for years to come.
We have three golden vicary privets and are wondering when is the best time to prune them?
I’d probably hold off pruning your shrubs for now. Cutting back a plant is a natural growth stimulant. The plant will try to replace the lost growth by pushing out new shoots.
You really don’t want to be doing anything to stimulate new growth in most plants in the fall. It puts the plant at risk of damage due to early frosts coming in the next month or two.
I want my plants to be starting the process of getting ready for a long winter’s nap.
If you want to do it this year, you could go ahead once the leaves have dropped. If you have the luxury of time, I think March is a little better.