Establish Natural Defenses
To encourage populations of beneficial organisms that help fight pest problems in your yard, improve the soil by adding organic matter to it. Soil rich in organic material, or humus, teams with microlife that attack pest insect eggs and provide nutrients for plants to keep them healthy. Mulching is the easiest way to add organic material to the soil. As it slowly decomposes, earthworms pull the humus beneath the soil surface, improving soil structure and drainage in the process.
Spread 2 to 4 inches of an organic material such as chopped leaves, grass clippings, compost, hay, shredded paper, or straw over the soil all season long. Peat moss makes a good mulch as long as it’s mixed with coarser materials such as chopped leaves or shredded paper. Used alone, it tends to crust over and repel water.
In addition to improving the soil on your property, encourage the many insects and animals that normally prey on borers by planting many different kinds of plants that they like. The natural predators of borers come in all shapes and sizes. While many are insects themselves, others are microscopic organisms, amphibians or birds. They will take up residence in a yard that includes their favorite plants and other foods. The greater the variety of plants on your property, the greater will be the diversity of natural enemies of pest insects that will be attracted to it.
Keep Trees and Shrubs Vigorous
Sometimes, when a tree or shrub has borers but has not yet been seriously damaged, simply helping the tree or shrub get stronger will allow it to resist further borer invasion and reduce the impact of those borers already at work. Many borer species remain in the tree only for about 1 year. Then they turn into adult moths or beetles and lay eggs to make more borers. Try to detect borers before they can do much damage and maintain plant health.
Fertilize and water young trees and shrubs properly to get them off to a strong start. Mulch them year round to enrich the soil over their spreading roots and protect them from injury by lawnmower or string trimmer. If a plant has borers boost its vigor with a seaweed/kelp-based bioactivator product, or plant tonic, that contains many trace elements and vitamins to supplement the fertilizer. Spread a 1 inch layer of real compost or composted municipal sludge on the soil over its roots at least out to its drip line to provide extra food to soil-dwelling microorganisms which provide nutrients to the plant.
Correct Conditions That Encourage Borers
Preventing or alleviating stress is the first line of defense against attacks of most borers on residential trees, shrubs and other woody plants. Maintain their vigor with proper fertilization, watering, mulching, and pruning. Avoid injury by lawn mowers and string trimmers that later become the front door for borer invasion. Make sure that they receive proper sunlight and air circulation as they grow larger.
If pruning is necessary on a tree or shrub, do it in late winter unless it is scheduled to bloom right away in the spring. Delay pruning spring bloomers such as azaleas, lilacs, magnolias, rhododendron and viburnums until shortly after they bloom but before they form next year’s flower buds later in the summer. Winter pruning avoids flying borer adults that might be attracted to the fresh pruning wounds.
Cut off injured stems and branches with a pruning saw or loppers promptly because jagged stumps make it easy for borers and other insects to invade a plant. Make a smooth cut back where the branch meets the main limb or trunk, leaving the roughened ridge of transitional bark, called the branch collar, protruding slightly. Its specialized bark cells grow quickly to heal the wound naturally. Do not paint over the wound unless it is a lanoline based product.
Wrap Trunks Of New Trees
Newly transplanted trees and shrubs are more vulnerable to borer attack than mature ones. To protect them while they are adjusting to their new site, wrap trunks or shrub stems with a quality commercial tree wrap material. After 2 years the material will begin to disintegrate and should be removed. This is ample time for the tree to become well-established.
Attract Beneficial Insects to the Yard
Birds, spiders, and predator insects kill many more borers than homeowners armed with insecticides ever can. Ants, spiders and predatory beetles prey on borer eggs before they hatch. Many parasitic wasps go right into borer tunnels and either kill and eat the borer or lay eggs on the borer that kill it later. If you avoid using broad-spectrum insecticides, there are probably beneficial insects already on your property. To combat borer problems consider adding more to bolster their efforts. Many kinds of beneficial insects are available from mail-order suppliers.
Encourage these natural predators of borers and other pests to stay in your yard by providing them with a tempting variety of their favorite plant sources of pollen and nectar. One product, Border Patrolä, is a seed mix of wildflowers particularly attractive to beneficial insects for planting on your property.
Invite Birds Year Round
Birds are also borer predators. Meat-eaters such as woodpeckers, nuthatches, vireos, kingbirds and crows eat borers or borer eggs. The real indicator that you have borers may be lots of woodpeckers and sapsuckers in your neighborhood all of a sudden. Borers are their favorite food and as they peck bark in their search for borers they, unfortunately, sometimes damage trees and shrubs themselves. Generally they don’t seriously damage a tree if there are just a few borers. In cases of major infestations, the plant is typically already severely damaged before the birds arrived. If it is a big tree, then it is time to contact a professional arborist for an assessment.
Hosting Birds In Your Yard
To encourage bird predators of borers and other pests to visit and patrol your yard, and maybe even set up housekeeping in the vicinity:
Feed Birds: Put out seed and other foods such as suet blocks for birds in the winter. In the spring and summer cut back on the amount of bird food you have in your bird feeders, but provide snacks regularly during the growing season to encourage more bird families to nest in your yard.
Water Birds: Water is critically important to birds year round. Keep 1 or 2 bird baths, filled with fresh water. Locate them far enough away from the cover of shrubs to avoid problems with the neighborhood cat while simultaneously affording birds a chance to flit back and forth and feel safe. Consider acquiring an automatic self-filling bird bath or a bird bath heater so that water is always available.
Provide Shelter: While woodpeckers and some other borer predators prefer to live in cavities of trees, other birds, such as chickadees, house wrens, sparrows, and purple martins will live in a bird house if you provide one that is the correct size and mounted at the correct height. Bird houses are easy and inexpensive to buy or build and are readily available from mail order catalogs.