Canker diseases
A canker is a sunken area containing dead tissue on a stem or
branch. It may not be clearly visible, or it may be a well-defined
infection on woody parts that often becomes surrounded by layers
of callus tissue. Cankers can cause foliage on infected branches
to turn yellow or brown and wilt. Infected bark often discolors
and may exude copious resin. On some canker diseases, small fungus
fruiting bodies may appear on the lower surface of affected leaves
and branches. Cankers can girdle and kill limbs or the entire
plant. Many pathogens and abiotic
factors cause cankers on various tree species.
Solutions
Planting resistant cultivars, if available, is
the primary strategy for managing canker diseases. Avoid planting
species that are poorly adapted for local conditions. Provide plants
with proper cultural care to keep them vigorous and to limit these
diseases. Prune out dead leaves and dead and dying branches when
they are first observed. Make the cuts in healthy wood beyond any
apparent cankers. Once the main trunk is infected, pruning is of
little value. Provide plants with moderate amounts of fertilizer
to improve plant growth, except for pines, which shouldn't be fertilized
at all when suffering from cankers. Avoid heavy fertilization,
which may promote disease. You can find more information on pine
pitch canker in the Pitch
Canker Pest Note. |
Cytospora canker
Pine pitch canker on Monterey pine
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