Aspen trees and several reasons they can brown

I have a group of aspen trees in my yard. They were all planted six or seven years ago. It seems like every summer the leaves get brown on the edges and just look sick and tired.

My neighbor down the block a couple of houses has some that are about the same age and his trees look a lot better than ours. Why is this? Should we doing something differently? Is it a special variety?

— Ed

I think you’re mostly seeing a typical aspen reaction to life down here in the valley. You see, aspen aren’t naturally adapted for life at lower elevations. There are lots of the trees growing here but they’d much rather be up at 10,000 feet where it’s 30 degrees cooler and it rains every afternoon (but then wouldn’t we all!).

There are three things that happen to aspen trees when we grow them here.

First, they don’t live very long. Aspen typically live 15–20 years here, which isn’t that old for a tree. The second thing is that we don’t tend to get the great fall color we do with trees growing in the mountains. They typically turn a yellowish-green-brown and drop.

The last thing that happens here is that it’s common for the leaves to scorch during the summer. Depending on the tree, its care and the weather, this halo can be a faint coloring at the edge or it can work its way to the middle of the leaf with the majority of the leaf turning brown or black. This is again caused by the environment here.

A leaf scorch simply means the leaf is losing water faster than it is being replenished through the roots and stems. This doesn’t mean you need to water more (that can make the problem even worse), it’s just that they’re not used to coping with our heat and low humidity. The tree may look a bit haggard by the end of August, but it will sprout out fresh green leaves next spring.

Sometimes, however, this issue indicates the tree isn’t getting the care it really needs. This usually boils down to watering. Make sure that the tree is soaked deeply but that the soil is allowed to dry slightly before soaking it thoroughly again. I think it’s helpful to do a little digging into the soil to verify that.

There are several possibilities that explain the difference between your trees and the neighbor’s trees. It might go back to watering. Your neighbor might be watering more or less or more deeply, which is what his trees might really need.

Before you just automatically adopt the neighbor’s watering schedule, the soil in your yard might behave differently and require a different schedule. You really have to do some digging on your own to see what’s going on underground.

Another possibility is simply that there are differences from tree to tree. This can be because of how well it did or didn’t take to digging and transplanting or simply genetics.

Some plants just are naturally rougher and tougher and others, not so much. There might also be differences in soils in your yard and the neighbor’s or they did a more thorough job of amending and improving the soil when the trees were planted.

Maybe your neighbor’s trees are a little better protected from the blazing hot afternoon sun or there’s a better mulch layer beneath the tree.

Shoot, there are a 100 possible explanations for this difference.

Concentrate on providing good care to your tree and hang in with it. I think it should be fine in time and besides, in spite of how they look by the end of summer, they’ll come back next spring.

Dennis Hill is the nursery manager at Bookcliff Gardens, 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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