WSU Extension

Hortsense

Poplar
 
Disease
Bacterial blight 
Canker 
Leaf and shoot blight 
Leaf blister 
Leaf rust 
Marssonina leaf spot 
Insect
Carpenterworm 
Oystershell scale 
Poplar petiole gall aphids 
Poplar-and-willow borer 
Satin moth 
Tent caterpillars 



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Caption: Poplar Marssonina leaf spot
Photo by: R.S. Byther
  
Poplar : Marssonina leaf spot
(revision date: 4/11/2018)


Biology
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


Non-Chemical Management
  • 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.
Select non-chemical management options as your first choice!

Chemical Management

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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Fung-onil Multi-Purpose Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 60063-9-4
  • Bonide Infuse Systemic Disease Control
    Active ingredient: propiconazole  |  EPA reg no: 100-773-4
  • GardenTech Daconil Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 67572-82-71004
  • Ortho Max Garden Disease Control Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 239-2522
  • This list may not include all products registered for this use.
Images

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Caption: Poplar Marssonina leaf spot
Photo by: R.S. Byther
Caption: Poplar Marssonina leaf spot
Photo by: R.S. Byther