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Cankers and dieback (various fungi) |
Discolored or rough areas in the bark may be seen on dead twigs or branches. Lombardy poplars may die from basal cankers. |
See the PDC Fact Sheet "Twig Blights and Cankers". Prune out affected areas well below the diseased area. |
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Marssonina leaf spot (fungus) |
Brown, circular spots with a dark-brown margin. Premature defoliation may result. The fungus also causes a twig blight, resulting in dieback. |
Refer to the PDC Fact Sheet "Leaf Spot Diseases of Shade Trees and Ornamentals" for more information. Rake and remove fallen leaves. Use Bordeaux, other copper-containing fungicides, chlorothalonil or maneb. May be applied in early spring as new leaves are emerging. |
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Mycosphaerella (Septoria)
leaf spot and stem canker (fungus) |
Leaf spot appears as sunken, black flecks that coalesce to form large and irregular blotches. Cankers (sunken and discolored areas of bark) may girdle stems, resulting in dieback. |
The most effective means of control is to plant clones with resistance (See resistant varieties). Use thiophanate-methyl or chlorothalonil for leaf spots if necessary. Refer to the PDC Fact Sheet "Leaf Spot Diseases of Shade Trees and Ornamentals" for more information. |
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| University Outreach and Extension does not endorse commercial products. Follow the label on all pesticides. |
