Homegrown: Oct. 29, 2011

I have two aspen trees in my front yard that were planted in the spring of 2000, and both were doing beautifully until this year.

One of them is still lovely with lots of leaves. The other has fewer leaves and those leaves are very tiny. In the spring, I even cut off a couple of limbs that appeared to be dead.

Do you have any idea what could be causing this? They are both planted in a rocked area and so are not scraped by a mower or anything.

— Rita

I’m assuming your tree looked healthy and full at one time and that this is a change in how the plant looked.

If it’s always looked this way, that’s another issue and we can talk about that, just let me know.

If, in fact, the tree has regressed, my first worry is a fungal disease called cytospora canker.

This guy can occur on a wide range of different host plants, but we see it overwhelmingly on aspen trees. It’s a stress-related disease, attacking trees that are weakened for one reason or another.

We see it most often on newly planted trees (since they can often be under some stress in the digging and transplanting that goes on); older trees (15–25 years old, since that seems to be about the life span of aspen down here in the Valley); or on trees that have been neglected.

I’m not sure what’s going on in your case; the tree is past that initial transplanting stage, it’s not that old, and I’m sure you’ve been taking good care of the tree.

Sometimes, we just don’t know what’s going on.

The disease travels through the vascular tissues of the plant, killing the tissues and choking the plant to death. Branches with small, sparse, pale green or yellow leaves are usually the first symptom. That’s followed by death of smaller twigs and then larger branches.

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. We don’t have any fungicides that will do the job for you.

About all you can do is to cut the infected tissue out by removing the branch that’s involved completely. That’s usually not an option because by the time we figure out what’s going on, the disease is in the trunk of the tree and you end up cutting the tree down, anyway.

Now that I have you sufficiently panicked, you might take in a branch that is dying and one that is dead to the CSU Extension Office or one of the independent nurseries in town to look at to confirm that this is what’s really going on.

If you do have cytospora, you’ll want to remove that tree as soon as it’s practical before the disease has a chance to spread to your other aspen.

Our trumpet vine is finally growing beautifully this summer and I noticed it has seed pods on it. My question is, when the pods are mature, can we plant the seeds? I didn’t know trumpet vines grew pods.

— Priscilla

Trumpet vine can be prolific producers of seed pods. Wait until the pods start to turn yellowish or brown before picking them. You can then let the pods dry thoroughly and harvest the thin papery seeds.

The seeds will germinate better and more consistently if you give them a period of cold treatment called scarification. They need about two months of temperatures below 40 degrees to germinate well.

Most people harvest seed in the fall and store the seed in zip-lock bags in the refrigerator over the winter to plant in the spring.

Dennis Hill is the nursery manager at Bookcliff Gardens, 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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