Treating insects that attack fruit trees can be a tricky matter. Many insecticides will also harm pollinators such as butterflies, moths and bees. Know the types of insects that can affect your fruit tree and be on the lookout for signs of their presence before beginning any spraying program. Understanding the life cycles of both your fruit tree and the insects it is prone to will make the selection and use of insecticide an easier choice.
Insecticides are chemical or organic means of controlling insects that can be harmful to plant life—in this case, fruit trees. Their purpose is to deter, inhibit or destroy insects that might feed on or nest in fruit trees, rendering them unattractive and unproductive, or even killing them. Insecticides must be used with caution as they will often injure helpful insects and can pose health risks to humans and pets if not handled correctly.
Insecticidal soap is commonly used to treat for aphids and psyllas. Dormant oil is a petroleum-based product that smothers eggs and larvae that overwinter in fruit trees. It is one of the few insecticides that insects do not become resistant to, but it is not effective on all types of insects. General-purpose mixtures come premeasured and mixed, requiring the home orchardist to simply apply according to label instructions. Specific chemicals are used to treat specific insects and should also be used in accordance with label instructions.
Many commercial insecticides are packaged together with fungicides or combined with them to treat fungal and bacterial diseases. This makes application convenient but can be a problem because issues created by fungi and insects do not always occur at the same time. Many fungal diseases emerge in the spring when conditions are warm and damp. This is the same time frame when bees are pollinating flowers, which will eventually lead to fruit. A general-purpose pesticide may rid your fruit tree of disease but may also destroy the bees you need to pollinate it.
Care should be used when applying insecticide to keep the chemicals out of your eyes, nose and mouth. Even your skin should be covered to prevent excessive contact. This becomes even more important when you have more than just one or two trees to treat.
Some insecticides are not safe to use as fruit nears maturity. Always check the labels before applying any insecticide.
Before applying any insecticide to your fruit trees, check the trees for insect infestations. There is no need to spray if no insect problem exists. This can actually lead to insects building a resistance to the insecticide and a problem developing in the future. Make sure to use the appropriate insecticide for the type of insect problem you have. Check the surrounding environment to determine if other plantings are drawing the offending insect to the area. Removing the cause can eliminate the need to use insecticides.
Dormant oils are applied when the tree is dormant. In this way they are present when spring conditions bring the tree and any overwintering eggs or larvae to life. Insecticidal soaps can be applied before flower buds open and throughout the growing season once petal fall is completed. It is important to understand the insect you are treating for, its breeding patterns and when the most effective time is for application of any other chemical insecticide. Check with your local extension office for guidance in dealing with specific insects.