Insect and Mite Pests
Information on specific insect, mite, and disease problems of pome fruits follows.
The apple maggot, Rhagoletis pomonella, is a serious apple pest that often damages homeowners' fruit. Careful management, however, including treating with insecticides and trapping adults before they lay eggs can reduce the chance of injury.
The codling moth, Cydia pomonella, is a constant threat to apple production in Pennsylvania.
Since 1985, European apple sawfly (Hoplocampa testudinea) has extended its range from the northeastern portion of Pennsylvania to the Maryland border. Now this pest is common throughout fruit orchards located in all fruit-growing areas of Pennsylvania.
The European red mite, Panonychus ulmi, a major tree fruit pest that attacks apples, stone fruits, and pears, is considered to be one of the most important indirect apple pests in Pennsylvania.
Green aphids include two species that are very difficult to distinguish, the apple aphid, Aphis pomi, and the spirea aphid, A. spiraecola.
The gypsy moth, Lymantria dispar, might attack fruit trees, especially apple trees, causing leaf damage. Damage can be severe on young trees, where defoliation can stunt or kill the plant.
Oriental fruit moth, Grapholita molesta, is a pest of most stone and pome fruits. In pome fruits, its appearance and injury is similar to that of the codling moth and lesser appleworm.
Pear psylla adults, Cacopsylla pyricola, look like small cicadas. They are about 1/10 inch long and are dark reddish brown. The adults, which overwinter on trees or other sheltered places, become active any time the temperature is above 40°F. Females begin laying tiny, pear-shaped, yellowish eggs in cracks in the bark and around the buds in late March and continue through the white bud stage.
Pennsylvania weather is variable during May and June, frequently changing from periods of cold wind and rain to stretches of abnormally high temperatures. These climatic irregularities govern the activities of the plum curculio, Conotrachelus nenuphar, a pest injurious to pome and stone fruits throughout the state.
The rosy apple aphid, Dysaphis plantaginea, has been a major pest of apple trees, causing both direct and indirect injury since the end of the nineteenth century.
The San Jose scale, Quadraspidiotus perniciosus, is a pest of fruit trees; it also attacks many other trees, as well as shrubs. Once established, most scale insects are difficult and expensive to control.