Q. I have a peach tree planted in 1998 with the bark lifting from the trunk easily. My gardener doesn’t know what this is or how to treat it. Can this tree be saved? A. This is borer damage to your peach tree and is the usual reason for their death at an early age. The damage is done by an immature stage of a beetle. Some people called them “worms” but they are properly called larvae. The adult female beetle flies looking for a mate during the spring and summer months. Once she mates than she lays eggs on many different kinds of trees including fruit and many landscape trees and shrubs. It appears she is attracted to trees damaged by a lack of water or intense sunlight on the limbs. Reducing damage to the tree because of intense sunlight is thought reduce damage by boring insects. This is done by “whitewashing” limbs, particularly on the upper surface, with a mixture of white latex paint and water in a 50/50 mix. Whitewashing these limbs reduce, but do not eliminate , damage created by intense sunlight. If you look closely you will see most of the damage is either on the upper surfaces of these limbs or on the sides of limbs that are facing south or west. These directions are where the most intense sunlight comes from. When pruning peach trees in particular, which seem to be very susceptible, try not to prune so much out of the tree that it lacks the shade needed to protect the limbs from intense sunlight. Here are a couple of postings on my blog. http://xtremehorticulture.blogspot.com/2015/08/identifying-their-damage-and.html http://xtremehorticulture.blogspot.com/2014/02/mechanical-control-of-borers-in-fruit.html Trees that get borers sometimes go into a death spiral; borers continued to attack these limbs or more limbs, limbs die and open the canopy for more intense sunlight which causes more damage which attracts more borers. There are no safe insecticides or chemicals that you can apply to these trees to cure the problem. The best approach I have found is removing the damage from the trees with a very sharp knife and let the tree heal on its own.

Q. Concerning my peach tree, it looks like the peach tree borer is my most significant pest. Being that the Bt pesticide spray is a great organic preventative and killer of the borer, and I already have it and use it in my vegetable garden, shall I just spray the peach tree once a week as a preventative? If I do, how long do I keep this up until the threat is over? Are there any other insects to worry about such as aphids? Branch dieback due to the borer that gets in the tops of sunburned branches. No real pesticide available for keeping this pest out. Whitewash and don’t overprune the canopy. A. There are two different borers which we must be careful not to confuse. Control is entirely different between these two borers. The borer you refer to damages the trunk and limbs of many trees including fruit trees as well as ornamentals. This borer is very difficult to control with pesticides.             Bt, an organic spray made of a bacterium, will not kill these deadly borers which we see as damage and dieback of limbs and entire trees. Bt sprays will, however, kill a borer which causes wormy peaches, nectarines and apricots. This borer is called the peach twig borer.             Peach twig borer kills the soft, succulent growth of peaches and nectarines at the beginning of the growing season. We should start seeing this damage right now. Its lifecycle is very short and so the population of this pest builds very quickly to enormous numbers in a matter of a few months. Flagging or new growth dieback due to peach twig borer on almond. The look is the same on peach or nectarine.             As peach, nectarine and apricot fruit matures and gets close to harvest, the attacks from this pest switch from soft, succulent growth to soft succulent fruit. These new attacks result in wormy peaches, nectarines and apricots. Instead of shoots which dieback, the fruit becomes infested instead.             The trick is to get this pest under control as early in the season as possible to prevent this pest’s population from exploding in numbers. We use sprays such as Bt or Spinosad early in the season, starting now, to help keep these populations small and under control.             I usually apply one of these chemicals when I start to see a few new shoots of peach and nectarine begin to die back. We call this flagging. We also use special traps which catch and monitor this insect when it is hatching and flying. You will see pictures of this on my blog.             This flagging is one indicator that you need to get out there and start spraying to knock their numbers down and protect the fruit. One type of pheremone trap used for trapping peach twig borer             Unfortunately there is not much that you can do to prevent the more damaging borer, a beetle in its mature form, from laying its eggs on the upper surfaces of sunburned branches. These insect eggs hatch and the larvae penetrate the tree through its bark causing extreme damage to the limbs by tunneling just under their surface.             The peach twig borer adult on the other hand is a moth and its immature form is also a larva but resembling what we might call a “worm” in appearance. The BT sprays do not work on insects which are in the beetle family, only those whose adults are moths.             Aphids are not a big problem on peach like they can be on plums and plum relatives like pluots. Aphids like cool weather and begin to disappear when it gets hot. Their damage is usually cupped or distorted leaves which are frequently sticky due to feeding by the aphids.             Because the aphid season is short in our climate, they are usually not worth controlling unless we have a prolonged cool spring.