Damage, disease possibilities in problems with cottonwood tree

We have a 4-year-old cottonwood that is about 20 feet tall. It has done very well in the past, but not this spring.

There are some new leaves near the bottom, but it looks dead the rest of the way up. We did give it some water during the winter.

Could it be that these cottonwoods are that far behind?

— Rob

I’m afraid I probably have some bad news for you. Though this has been a late spring, by now cottonwood is pretty much all leafing out and growing.

What you’ve described sounds like something sneaked in and killed your tree. There are a couple of possibilities that come to mind.

The first is that the tree was girdled with a string trimmer while trimming the grass away from the base of the tree. It’s terrible how often I see this. Sometimes it seems string trimmers were made just to strip the bark off of the base of young trees.

The damage is sneaky, happening a little bit week by week. While this is happening, the tree often looks fine until the damage becomes too much and then the tree suddenly collapses or doesn’t leaf out in the spring.

I always recommend that people kill a circle of the grass out about a foot from the trunk by spraying it with Hi-Yield Kill-Zall. People worry that it will look terrible, but the truth is that after the grass is dead and gone, most folks don’t even notice it. Not only does it protect the tree from this accidental damage, but it makes mowing the lawn faster and easier.

You can easily see if this is the problem by looking carefully at the base of the tree to see if the bark has been eaten away.

The second possibility is that a disease killed your tree. There’s a common fungal disease called Cytospora that kills cottonwoods as well as many other trees. It’s a stress related disease, attacking trees that are weakened for one reason or another. I’m not sure what’s going on in your case; there are a host of possible culprits out there.

The disease travels through the vascular tissues of the plant, killing them and choking the plant to death. If your tree does have Cytospora, I’m afraid you’re eventually going to lose the tree and there’s really nothing you can do about it. There just aren’t any fungicides that will kill it.

This problem is a bit harder to diagnose, but if you run your fingers lightly over some of the smaller twigs out near the ends of the branches, you’ll sometimes feel fine pimply bumps which are the fruiting bodies of this fungus.

Do you recommend milky spore for lawn grubs in this area?

— Monte

To tell you the truth, I haven’t had much success with milky spore to control grubs.

It’s a great idea in concept — start a disease outbreak in the grub population that is spread from insect to insect that wipes them out and has no effect on other things around there.

I don’t know if it’s the packaging of the disease or what, but when I want to control grub, I’m reaching for an insecticide to apply in late June to kill the newly hatching grubs.


The last three years I have had twin fruit on my nectarine tree. The tree is only 6 years old and shows no sign of stress. I water it regularly.

— Henry

Double or triple fruit is usually due to adverse weather during bloom. It can be caused by excessive cold or heat or even high winds as the flower is just initiating in the spring. It really doesn’t affect fruit quality aside from it looking a bit odd.

Dennis Hill is the nursery manager at Bookcliff Gardens, http://www.bookcliffgardens.com. Send questions to Bookcliff Gardens, 755 26 Road, Grand Junction 81506; or email .(JavaScript must be enabled to view this email address).


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