We have some big old cherry trees in our yard and the tops of them are dying off. They have been in the yard for years, and this just started up last year. Why would this happen, and is there something we can do for it?

— Paula

There are a couple of problems that could cause this.

Peach tree borer or crown borer is an insect that is a problem with all stone-fruit type plants such as peaches, plums, cherries and apricots and their ornamental relatives.

These insects tunnel around under the bark, but are usually only found down near the ground.

Take a look at the trunk at ground level or even an inch or two below ground level. If you have the borer, you'll usually see loose, cracking and peeling bark with some gummy, jelly-like ooze (big old trees with thick mature bark might not show this).

If you see any of that, there are some effective drench treatments you can apply to prevent this little monster from bothering your tree, and we're at the perfect time of the year to start doing it.

Those drenches should be applied from the first of June into August. When you get a chance, come into the store, and we'll give you a sheet with information on it and how to treat it.

The second possibility is that you have a fungal disease called cytospora canker.

Cytospora is always a problem on trees that are weak and under stress for one reason or another (the stress is usually because of peach tree borer damage).

Treating the borer will allow the tree to heal itself. A healthy tree will usually be able to fight off the disease by itself. Unfortunately, we don't have any effective fungicides that will help you with this problem. Concentrate on getting that tree as happy and healthy as you can.

I have two crabapple trees I am about ready to cut down because of the mess when the fruit drops off. I would rather keep them because they have a nice shape and are pretty good-sized.

Is there something I could do to stop the trees from producing fruit?

— Brent

The problem you're experiencing is not unusual with people who have older varieties of crabapple. They bloom beautifully in the spring, set showy fruit in the summer and then it all falls off in the fall making a slimy mess.

Just so you know, there are some real improvements in crabapple trees today. Most of the ones we carry now have persistent fruit. Instead of it all falling off in the fall, it hangs on the tree all winter, providing color as well as food for the birds.

Anything that's left will fall off in the spring when the new growth pushes out, but by then they're just a shriveled up little raisin, not the mess you fight in the fall.

There is a product you can use to prevent aggravating fruit from setting. We sell a product called Florel, which contains a plant hormone called ethephon.

Unfortunately, it's too late in the season to do any good, but next year you'll want to spray the tree twice, the first time at full bloom and again about two weeks later.

The product isn't perfect. There are years it will eliminate 99% of the fruit, other years when you wonder if you did anything at all.

On the average, I'd say it should get rid of 80–90% of the fruit. Make sure you do a good job covering the tree with the spray, and your messy fruit problem should be a much smaller one. The bad news is you'll have to spray your tree every year. It only causes the fruit that is present at the time to drop off, it doesn't sterilize the tree.

A more permanent, long-term solution involves pruning the tree with that old one-cut method right at ground level.

You could replace it with one of those newer crabapple varieties; there's even a fruitless one called Spring Snow.

Dennis Hill is the nursery manager at Bookcliff Gardens, bookcliffgardens.com. Send questions to Bookcliff Gardens, 755 26 Road, Grand Junction 81506, or email info@bookcliffgardens.com.

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