Poplar: Marssonina leaf spot

categories: Ornamental trees Ornamentals Poplar Poplar Diseases

revision date: 2024-06-05 02:07

Poplar Marssonina leaf spot on a black background.
Poplar Marssonina leaf spot
Photo by: R.S. Byther


Marssonina leaf spot is a fungal disease which is favored by wet weather. Leaves develop spots or flecks which are initially bronze or brown with yellow edges. These spots enlarge and may involve almost the entire leaf. Later, the spots turn black and may have gray fungal fruiting bodies on the surface. Severe infections may result in premature leaf drop, which can reduce growth. Twigs may also be infected. The fungus overwinters in infected leaves on the ground. Trembling or quaking aspen (Populus tremuloides), Eastern cottonwood (P. deltoides), black cottonwood (P. trichocarpa), and balsam poplar (P. balsamifera) are typically infected.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Space plantings and prune to improve air circulation.
  • Prune and destroy infected twigs. Disinfect pruning tools after use.
  • Rake and destroy (do not compost) infected leaves.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • Apply fungicides at budbreak to protect new growth.
  • Homeowners should not make foliar applications to trees over 10 ft tall.
  • Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

Additional Image