| Anthracnose is a group of related fungal leaf and
stem diseases that infect shade trees. Maple
anthracnose is not the same disease as oak
anthracnose, although the symptoms of these
diseases may be quite similar. Anthracnose diseases
generally infect the leaf veins and cause death of the
vein and surrounding tissue. Control of anthracnose
diseases follows the same procedure for all shade
trees affected. The disease does not cause the death
of the host but may reduce growth over successive
seasons of complete defoliation.
Symptoms and Diagnosis
Irregular, light brown spots of dead tissue develop
along the veins of the leaves. Affected plants may
have the appearance of being sun-scorched. Sunken
cankers containing fungal spores develop on
infected twigs of some trees, such as sycamore.
Life Cycle
Anthracnose fungi overwinter on fallen leaves and
twigs that were infected the proceeding year.
Infection is favored by cool, moist weather in the
spring of the year. Infection can occur on the
vulnerable young leaves when there is a film of
water on the leaf surface. Infection is typically more
severe on the lower third of the tree, where the
humidity is the highest.
Integrated Pest Management Strategies
1. Collect and destroy infected leaves as they fall.
Infected leaves and twigs that remain in the
vicinity are a source of spores for new infections
in the spring.
2. Prune out dead branches. Be sure to clean all
garden tools to avoid the spread of the disease. A
1–part bleach to 9–part water solution can be
used to dip tools into between cuts.
3. Promote air circulation. Thin out excessive twig
and branch growth. This will reduce the period of
time that leaves are wet and vulnerable to
inoculation.
4. Keep trees growing vigorously. Supply 1–2 inches
of water weekly only during dry periods. Fertilize
early in the spring or in late fall.
5. Spray with a fungicide when leaves are beginning
to enlarge from the buds. Reapply at 7–10 day
intervals for two or three more times. Fungicide
sprays are most appropriate for younger, newly
transplanted trees that may not be able to
withstand defoliation. The available fungicides are
preventive, not curative, and therefore, must be
applied before spotting occurs. Commonly used
products include copper, chlorothalonil (Daconil),
captan, ferbam, mancozeb, maneb, and thiram.
Your pesticide choice should be based on the
particular problem you are seeking to control.
Consult an arborist for difficult situations and
where power equipment is required. | 
