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.
- Workshops
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Blueberry Growers Twilight
When 04/05/2024Length 2 hoursRefine blueberry cultivation with pruning, soil nutrition, and disease insights. Penn State experts share strategies for success. Ideal for all growers. - News
2024 Disease Update: Dormant Copper Sprays and Orchard Sanitation
Date Posted 3/4/2024Early season disease management for the 2024 season should be underway. Consider dormant applications of copper to manage fungal and bacterial diseases on fruit trees. Sanitation is critical for limiting fruit rots in the orchard. - News
Lorsban/Pilot (Chlorpyrifos) is Back for Pennsylvania Tree Fruit in 2024
Date Posted 2/5/2024New developments for the insecticide chlorpyrifos (trade name Lorsban, Pilot, Warhawk, and others). - Articles
Orchard Wildlife - Integrated Management of White-Tailed Deer
The natural food habits of deer depend on the time of year and the plant species available. - Articles
Peach Disease - Peach Leaf Curl
The peach leaf curl fungus, Taphrina deformans, destroys early peach leaves. - Articles
Cherry Disease - Cherry Leaf Spot
Cherry leaf spot, caused by the fungus Blumeriella jaapii (formerly Coccomyces hiemali), attacks the leaves, leaf stems, fruit, and fruit stems of tart, sweet, and English Morello cherries. - Articles
Tree Fruit Insect Pest - Woolly Apple Aphid
The woolly apple aphid, Eriosoma lanigerum, is a widely distributed pest of apple trees, especially where its parasites have been killed by insecticides. - Articles
Apple Disease - Powdery Mildew
Powdery mildew, caused by the fungus Podosphaera leucotricha, attacks buds, blossoms, leaves, new shoots, and fruit of wild and cultivated apples and crabapples. - Articles
Orchard Wildlife - Integrated Management of Voles in Orchards
Voles are primarily vegetarians, feeding on grasses, tubers, and seeds. They also consume the bark of young trees. - Articles
Apple Disease: Moldy Core
Moldy core is caused by several different fungal pathogens. Many cultivars of apples are affected, including Delicious, which is very susceptible. - Articles
Apple Disease - Core Rot
Core rots are caused by various fungi. The most susceptible cultivars are Delicious, Golden Delicious, Gravenstein, and Idared, which all have an open sinus extending from the calyx into the core region. - Guides and Publications
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Tree Fruit Production Guide
Get the most up-to-date information on growing tree fruit on a commercial scale. Revised information and a refreshed look for 2024. - News
Environmental Protection Agency Mitigation Proposal Update: Ziram/Thiram/Ferbam
Date Posted 12/12/2023The first week in December 2023, the EPA hosted a webinar to address concerns and outline new measures for mitigating risks pertaining to using three commonly used fungicides: ziram, thiram, and ferbam. - Articles
Sources Of Plant Disease In Greenhouses
Where do diseases begin? It is important to prevent losses due to plant pathogens by reducing or eliminating the numbers of pathogens at their source. - Articles
Tree Fruit Insect Pest - Plum Curculio
Plum curculio, Conotrachelus nenuphar, is an injurious pest of apples, cherries, nectarines, peaches, and plums throughout the state. - Articles
Tree Fruit Insect Pest - Rose Leafhopper
Rose leafhopper, Edwardsiana rosae, is a minor pest on apples in the Mid-Atlantic region. Orchards in the vicinity of multiflora rose or brambles are especially at risk. - Articles
Tree Fruit Insect Pest - San Jose Scale
The San Jose scale, Quadraspidiotus perniciosus, is a pest of fruit trees, but it attacks many other trees as well as shrubs. - Articles
Tree Fruit Insect Pest - Shothole Borer
The shothole borer, Scolytus rugulosus, sometimes called the fruit tree bark beetle, is a native of Europe but now occurs throughout the United States. - Articles
Tree Fruit Insect Pest - Spotted Tentiform Leafminer
The spotted tentiform leafminer, Phyllonorycter blancardella, affects the leaves of apple trees throughout the growing season. - Articles
Tree Fruit Insect Pest - Spotted Wing Drosophila
The spotted wing drosophila (SWD), Drosophila suzukii, is an invasive species originally from Asia. - Articles
Tree Fruit Insect Pest - Variegated Leafroller
Although variegated leafroller, Platynota flavedana, is an important pest of apple in Virginia and West Virginia, it only occasionally causes damage in southern Pennsylvania. - Articles
Tree Fruit Insect Pest - Western Flower Thrips
Widespread fruit loss from western flower thrips, Frankliniella occidentalis, was first observed in early 1990. - Articles
Tree Fruit Insect Pest - White Apple Leafhopper
White apple leafhopper, Typhlocyba pomaria, was abundant in many apple orchards throughout the state until the introduction of the neonicotinoids about 10 years ago. - Articles
Tree Fruit Insect Pest -Tufted Apple Bud Moth
The tufted apple bud moth, Platynota idaeusalis, is a serious direct pest of apples in the five-state Cumberland-Shenandoah region of the eastern United States.