Pests and Diseases

Pests and diseases can have a severe impact on the health and economic output of forests. On this page, access educational resources on private forest pests and diseases. Additionally, find information on spotted lanternfly, worms, caterpillars, weevils, mites, knotweed, multiflora rose, and invasive weeds.

Invasive Forest Insects

Invasive, non-native insects compete with native species, affect local habitats, and alter the forest’s ecosystem. Invasive insect pests, such as the spotted lanternfly (SLF), are a serious ecological threat for Pennsylvania forests.

The spotted lanternfly feeds on many plants but is particularly attracted to the tree-of-heaven, an invasive forest tree. Comprehensive SLF management resources, as well as permit training for business, are available through Penn State Extension.

The emerald ash borer (EAB) is another destructive insect that can be encountered in PA forests. EAB is a wood-boring beetle that has caused the decline and mortality of many North American ash trees. Explore recent control efforts for EAB and other invasive forest pests during the Invasive Insects webinar.

Common Forest Pests and Diseases

Pests and diseases have a significant impact on forest ecosystems. They can affect leaves, stems, and crowns, which in turn can damage the condition and growth of trees. What is more, forest pest and disease issues can reduce wood quality and yields.

Cankers are among the more widespread tree problems. They can affect species such as elm, beech, and hemlock trees. In this section, you will discover informational tables on prevalent forest diseases, including ash, maple, and oak diseases. Private forest owners can learn how to diagnose and manage elm, beech, hemlock, and pine diseases as well. Tips on symptoms, causes, and management tactics are available.

Pennsylvania forests can be attacked by various pests, as well. A typical native pest of hardwood trees in North America is the fall cankerworm. Mature larvae feed on leaves and can often defoliate an entire tree.

Other forest insects, such as the tuliptree scale, can cover twigs and branches, resulting in a rapid tree decline. Landowners should further remain alert for signs of infestations caused by eastern tent caterpillar, birch leafminer, and white pine weevil.

Private Forests and Pest Management

Forest pest management is primarily focused on preventing the entry and spread of invasive species while maintaining the woodland’s biological health. Pest control options include biological, mechanical, and chemical methods, typically depending upon the damage-causing species. With pests such as the engraver beetle, chemical control is generally only necessary for high-valued trees in residential or recreational settings.

In many forests, invasive vegetation control is needed, as well. Before applying any herbicides, consider the Integrated Vegetation Management approach to ensure a healthy forest ecosystem.

Detailed information on identifying and managing forest diseases and pests can be obtained through Penn State Extension. Resources are also available on topics such as becoming a certified forest pesticide applicator, as well as managing tree-of-heaven as part of SLF control strategies.