If you’ve noticed sawdust and a gelatinous substance at the base of your peach tree it sounds like you may have the Peach Tree Borer. The oozing sap is more severe in early spring as the sap starts flowing, but you’ll see signs of it now along with frass, a sawdust like substance. The peach tree borer is a common problem in our area and attacks not only peach trees, but any stone fruit. A stone fruit is any fruit with a hard center pit, in the Prunus family, such as peach, apricot, nectarine, plum and cherry. It will attack ornamental trees as well so keep an eye on your flowering cherries and flowering plums, too. Most injury occurs at ground level to the trunk and roots but evidence of the borer may also be found about a foot off the ground. The Peach Tree Borer can kill young trees and weaken older ones, making them more susceptible to other disease and insect problems.
Now is the time to treat for this insect. The Peach Tree Borer a clear winged moth and resembles a dark colored wasp. In the Treasure Valley, they begin emerging from the tree in early July and continue through August. The adult does no damage, other than reproducing. Egg laying continues for about 6 weeks and your trees should be protected during that entire time. The female borer layers her eggs on the trunk and large lower branches and crotches of the tree. After hatching, the larvae crawl down the trunk and tunnel into the tree at soil level where the bark is soft and moist. The larvae will then chew its way into the tree where it pupates to emerge as an adult the next summer. While the borer is inside the tree they are protected from insecticides or other methods of eradication so getting them when they’re outside the tree is your window of opportunity. That’s why treatment time is so important. You can treat this insect with a product containing pyrethrin or permethrin (a synthetic pyrethrin) or neem oil, which can be found at D&B Supply. Treat the trunk, large lower branches and the crotch areas. Apply the product heavily enough to puddle at the base of the tree. There is no need to use the insecticide on the fruit or the leaves. Do not use a systemic insecticide. It does not work on this type of insect! The product label will tell you how often to spray, but remember, you should continue treating through the month of August for full protection.
Removing grass from around the base of your trees and keeping the mulch pulled back a few inches from the trunk will make the area a little less appealing to this pest. Remember, keeping your trees healthy and vigorous is your best bet in fighting insects and disease.