Warm, dry weather alters borer treatment

Please remind me of the spray and drench schedule for the peach, apricot, nectarine tree borer.

— Pat

Peach tree borer is the most common serious insect pest in fruit trees such as yours. This insect is a problem on members of the genus Prunus that set a “stone type” fruit. This includes peaches, plums, cherries, apricots and almonds.

It also can affect their ornamental relatives such as cistena plum, pink flowering almond, purple leaf plums, European bird cherries, Schubert chokecherry, flowering cherries, double flowering plum, Nanking cherries and more.

This sneaky little devil tunnels around under the bark like other shade tree borers, but it does it low down on the tree near ground level where many people don’t notice the problem until serious damage or even death of the tree occurs.

Treatment involves wetting the bark of the tree where this borer is active. However, it is also very important to carefully time the applications to achieve good control.

The way to treat the problem is to drench around the tree (use a watering can or a bucket) with Permethrin. On edible fruit trees such as yours, you want to use the 2.5 percent concentrate of Permethrin according to label directions.

There is a 38 percent concentrate available that we commonly use for borer control but it’s not labeled for use on edibles; you can only use it on ornamental plants with the problem.

Normally, we’d recommend that you apply the drench around your trees approximately June 20, July 10 and again on July 30. But this year, as warm and mild as the winter and spring has been, I’d probably start treating it earlier. Figure on starting your first drench now and then do the other three.

Wet the bottom 6–8 inches of the trunk and soak the ground immediately around the trunk. It really doesn’t take all that much of the insecticide solution to treat each tree.

I have a couple of peach trees on my farm that never ripen. They get fruit every year but they’re very hard and small and cannot be eaten. What can I do to help them?

­— Pam

I’m not really sure what might be going on with your peach trees. Trees that bear small peaches that are hard and never seem to ripen usually have one of four things going on.

First, it is a bad variety of peach. We often see this when people have grown a seedling or if the original tree died back and the rootstock sprouted up and replaced the original tree.

Either way, they will never make good peaches, and we usually end up replacing the tree with a desirable variety.

The second reason is stress on the tree. If the tree is hurting, it often doesn’t have the resources to fully ripen the fruit.

How does the tree look? Is it being watered deeply? Is it not allowed to dry out too much and not allowed to stay soggy? Are there insect or disease problems? You may need a visit from your local extension agent or a master gardener to check this out.

If there is something going on, and if you can figure out what it is and fix it, the tree should turn itself around and start producing good fruit.

The third reason is letting too much fruit remain on the tree. If this is the case, the tree just can’t ripen all that fruit and none of it turns out. Thinning the fruit to one fruit every 8-inch along the branches in late May or early June will help you here.

The last thing is immaturity of the tree. Trees less than 3 or 4 years old sometimes will do this. If this is the case, be patient and your fruit will come.

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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