Pests and Diseases

Fruit diseases and pests are extremely common, making the use of chemical controls an important part of the production process. On this page, fruit growers will find information and tips on managing diseases, fruit bugs, and insect pests on crops such as apples, pears, grapes, and berries. Advice on using fungicides, antibiotics, insecticides, and miticides can be found, as well.

Common Fruit Diseases

Fruits crops, like all other plants, are susceptible to various diseases that can cause adverse changes and affect production. Scab, for example, is among the most common pear and apple diseases.

Apple scab is caused by a fungus and early infection signs can be spotted on the leaves, stem, or blossom end of the fruit. Lesions manifest in dull, olive green areas or spots. To prevent secondary infections, it’s critical to scout and control apple scab early in the season.

Pear scab has very similar symptoms and disease cycles. Unlike apple scab, however, pear scab frequently appears on twigs, where it can survive during winter and start new infections in spring.

Gray mold is another prevalent cause of disease in apples and pears. The primary infection points for the introduction of gray mold are fruit injuries and wounds. The disease can easily spread from infected to adjacent healthy fruit in storage.

Penn State Extension offers in-depth information on a number of fruit tree diseases, including strawberry leaf spots and leather rot, wooly apple aphid, and phytophthora root rot in raspberries. Resources on common stone fruit and plum tree diseases are also available.

Tree Fruit Insect Pests

Fruit pests can cause a significant decrease in yield. One of the more devastating fruit tree pests is the spotted lanternfly. It is an invasive insect that feeds on a wide range of plants. Penn State Extension provides growers with Spotted Lanternfly Management Resources, as well as permit training and best practices to stop its spread.

Other common fruit tree pests include American plum borer, dogwood borer, and oriental fruit moth. Additionally, tree fruits can be attacked by various species of plant and stink bugs.

Orchard Integrated Pest Management

Integrated Pest Management, or IPM, allows fruit producers to ensure proper pest management decisions that are economically, environmentally, and socially sound. IPM begins with collecting detailed information about a crop and its pest, also known as scouting.

Regular field scouting is key to conserving soil and reducing pesticide use. Along with scouting, implementing IPM insect monitoring can be a cost-effective way to detect the presence of pests in traps placed in orchards.

For further information on orchard IPM, access the Field Guide to Tree Fruit Disorders, Pests, and Beneficials. The publication – available in both English and Spanish – can be beneficial to orchard employees, who are often the first to detect a fruit disease or insect pest.

Fruit Fungicide and Pesticide Application

Fungi-caused infections are one of the most prevalent orchard diseases. They are often managed with either fungicidal or fungistatic pesticides. Fungicides are separated into two categories: protectants and systemics.

Protectant fungicides are designed to protect plants against infections at the application site. Systemics prevent diseases from developing on parts of the plant away from the application site. Discover more with Penn State Extension’s resources on fungicide resistance, proper usage and maintenance, and fungicide recommendations for apple diseases.

Fruit growers can find guidance and tools for spray products usage, such as the Spray Record-Keeping spreadsheet. Advice on apple insect and mite control is also available, as well as certification training for private pesticide application.