If you’ve noticed sawdust and a gelatinous substance at the base of your peach tree, 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 the insect now, too. 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 a fruit with a hard center pit. These trees are in the Prunus family, which include 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 to the trunk at ground level, but evidence of the borer may also be found up to a foot off the ground and in the roots. The Peach Tree Borer can kill young trees and weaken older ones, making them more susceptible to other disease and insect problems.
The Peach Tree Borer is a clear winged moth that resembles a dark colored wasp. In the Treasure Valley, they begin emerging from an infested tree in early July and continue through August. The adult does no damage, other than reproducing, but that’s enough. Egg laying continues for about 6 weeks and your trees should be protected during that entire time. The female borer lays her eggs on the trunk and large lower limbs 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 their way deep into the tree where they pupate, to emerge, as adults, next summer. While the borers are inside the tree they are safe from insecticides or other methods of eradication so getting them while they’re outside the tree is your window of opportunity. That’s why treatment time is so important!
Now is the time to treat for this insect. According to the Pacific Northwest Insect Control Handbook,this insect may be managed with products containing permethrin or neem oil among others. Follow label directions carefully.Treat the trunk, large lower limbs and the crotch areas. There is no need to treat the fruit or the leaves. Do not use a systemic insecticide; It does not work on this 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 is your best bet in fighting insects and disease.