by Glen Arnold, Putnam County
Early spring is the best time to apply sprays to control certain insects, mites, and diseases on apple, pear and other fruit trees. Gardeners who have had problems with pests and diseases in the past year should consider applying early season sprays to prevent or minimize pest damage this season.
Certain fruit pests overwinter on the tree. These include the eggs of the European red mite and scale insects such as San Jose scale and oyster shell scale. These can be effectively controlled with oil.
Oils called “dormant oils” are intended to be used before the leaf or fruit buds of apple and pear trees open in the spring. For northern Ohio this usually occurs in early April. Applying dormant oils at this time can effectively control scale insects. Most gardeners need only consider dormant oil once every five years or so unless they have a history of trouble with scale insects.
Some oils are designed for delayed-dormant applications and are called Superior or Supreme oils. Apply all oils when temperatures are above 45 degrees F and when temperatures are not predicted to drop below 40 degrees F for 24 hours. Oil can cause leaf damage under cool temperatures, high humidity, or wet conditions. The oil also breaks down on the leaf when exposed to near freezing temperatures.
A fungicide spray applied in early April can go a long way toward eliminating scab diseases that may have overwintered on fruit trees. This is especially true if you dealt with peach leaf curl on your peach trees last summer. Apply the fungicide before the tree leaves emerge for best results. Be certain temperatures are in the mid 60’s or higher at the time of application. Most hardware stores carry general purpose fungicides that work well against fruit diseases. Products containing chlorothanol (Ortho’s Garden Max Disease Control and Daconil 2787 both contain chlorothanol) as the active ingredient are the best.
An insecticide spray can be effective at petal fall against other early pests such as codling moth, plum curculio, and leafrollers. Reducing insects at this time will minimize the number of adults and offspring present during the summer. It will also reduce the injury to fruit as they begin to grow.
Codling moth, which is usually the most serious pest of home fruit plantings, may be partially controlled by the petal-fall spray but is most effectively controlled about 2 weeks after petal-fall. In mid-summer (July), another insecticide application can control the second generation of codling moth as well as apple maggot.
Gardeners should read the label for all types of sprays and closely follow all precautions. A fungicide is generally required to control apple scab on susceptible cultivars. At half inch green (as soon as green tissue is present) and at tight cluster, a fungicide should be applied to most apple trees. To assure high quality fruit apply a combination of an insecticide and fungicide at tight cluster, pink, and petal fall. Fungicide may be applied during bloom but do not apply an insecticide at bloom to protect bees.
For more information on fruit pests, obtain a copy from your local Ohio State University Extension Office of Bulletin 780, Controlling Diseases and Insects in Home Fruit Plantings. This bulletin can be read online at http://ohioline.osu.edu/b780/
For descriptions of plum curculio, San Jose scale, leafhoppers, codling moth, and apple maggot, ask for HYG-Fact Sheets 2043, 2039, 2202, 2203 and 2041, respectively or go on-line and find these fact sheets at http://ohioline.osu.edu/