"In the ‘battle of beetles,’ I thought my 30-year-old snow ball bush was a goner. However, the treatments and pruning you recommended produced these wonderful results."

Bette, Greece

"Turfgrasses trap much of an estimated 12 million tons of dust and dirt released annually into the U.S. atmosphere."

Wood Boring Insects

There are a number of wood boring insects that attack a wide diversity of plants growing in our landscapes. They can be categorized as either beetles (i.e., the bronze birch borer) or clearwing moths (i.e., peach tree borer). Both have larvae that tunnel and feed within the plant tissue. Wood boring insects can kill plants directly due to feeding within the phloem tissue, which reduces the plants ability to obtain nutrients. Wood boring beetles can kill plants indirectly by serving as the carrier of certain plant diseases.

Most of the boring insects are generally a problem when plants are stressed. When plants are predisposed to stress, which can occur due to drought or mechanical damage (mowers), it increases their susceptibility to borers. Poor cultural practices such as watering, fertilization, mulching and pruning are also major causes of stress. Stress may cause plants to redistribute more of its resources towards growth, leaving fewer resources for defense. Borers will take advantage of this imbalance and find it easier to locate and attack stressed plants. In some cases borers can emit chemicals that attract additional borers. They then overwhelm the tree's defenses and hasten the plants decline.

To enhance overall plant health, make sure trees are properly watered. Drought stressed plants are unable to take up enough water to maintain normal functions. This weakens a plants defense system. Improper mulching can also weaken a tree. Too much mulch or mulch that covers the trunk flare can suffocate a plant. This will enhance borer activity. Mulch should be 2-4" deep and never piled up against a trunk. Topping of trees or poorly placed pruning cuts can often make it difficult for plants to properly heal themselves. These types of wounds are attractive to borers for insect laying since they are easy entry sites for the larvae. The timing of the pruning should also be considered so as to not enhance or attract additional borer activity. Proper site selection will also help to minimize problems with borers. Improper plant placement will weaken a plants defenses and make it more susceptible to a borer attack. This is quite often the case with Birch and Dogwood trees.

Information gathered from the University of Illinois Extension Newsletter. Feb 02 RN