Cottonwood and poplar
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. Prune out affected areas well below
the diseased area.
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. 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.
Mycosphaerella
(Septoria) leaf spot and stem canker (fungus)
Mycosphaerella (Septoria) leaf spot and on poplar
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. Use thiophanate-methyl or chlorothalonil for leaf spots if necessary.
- Susceptible to Mycosphaerella (Septoria) leaf spot and stem canker
All native North American species of poplar and aspen.
Note
Check with local nurseryman or catalogs for information about resistant
clones.
Updated 6/8/09