| Disease |
Symptoms |
Pathogen/Cause |
Management |
| Anthracnose |
Young unfolding leaves develop greenish-brown
to dark-brown spots at their tips, along their margins, and
between the veins. When fully expanded
leaves are attacked, light-brown to tan blotches form. Severely
infected leaves fall prematurely. Infected young twigs are girdled
and killed. Disease severity is greatest on the lower portion
of the crown. Fungal fruiting structures (acervuli) form in
the infected tissues and are only slightly darker in color than
the spots. A magnifying glass is required in order to find the
acervuli in the spots. |
Gloeosporium
aridum |
Remove and destroy infected twigs
and branches during dormancy. Rake and remove fallen leaves
in the autumn. Apply myclobutanil, chlorothalonil, mancozeb,
thiophanate methyl, or thiophanate methyl + mancozeb as the
young leaves and twigs are forming to protect them against initial
infections. Continued applications are required until the weather
becomes dry and daily temperatures average above 65°F. |
| Decline |
Tree growth slows. Tufts of numerous
branches form. Branch dieback progresses until much of the tree
is dead. |
Exposed site, heavy, poorly drained
soils, drought, canker-causing fungi, viruses, nematodes, and
phytoplasmas combine to weaken and kill the tree. |
Protect the tree from as many stresses
as possible. |
| Ganoderma Root Rot |
Branches die back as a root rot develops.
A very distinctive shelf-like fungus grows on the wood annually
singly or in overlapping clusters. These shelves are brown to
reddish brown on top with a cream to white-colored margin, and
may become 14 inches across. The upper surface may appear to
have been varnished. |
Ganoderma
lucidum |
The appearance of the fungus on the
tree is the last sign that the tree is severely diseased. Remove
the tree immediately if it is in a location where falling limbs
or the falling tree poses a threat to life or property. |
| Laetiporus root rot |
The bark is slightly depressed and
cracked in areas on trees with dying limbs. Infected trees are
very prone to wind breakage. Massive clusters of bright, sulfur-yellow
to salmon to bright-orange shelf-like fruiting sturctures that
turn white with age initially form in the summer or autumn on
the wood of the tree but fall off during the winter. The underside
of the fruiting structure has tiny pores in which the spores
are formed. New shelves form on the wood the following summer
and autumn. Fruiting occurs long after most of the damage has
been done. |
Laetiporus
sulfureus
(formerly Polyporus sulfureus) |
Remove the tree at the first sign
of infection since it poses a very serious treat to life and
property. |
| Rust |
In the spring along the east coast,
yellow-orange spots form on the leaves of white and green ash.
Leaves become distorted as orange fungal fruiting structures
form on the underside of leaves and on petioles. Cankers that
form on twigs and trees can be defoliated prematurely. The spores
formed on ash blow to and infect Spartina
(cordgrass) in salt marshes where the fungus overwinters. |
Puccinia
sparangioides |
Apply myclobutanil, triadimefon,
chlorothalonil, or a mancozeb in the spring to protect young
leaves and twigs of trees usually found with the disease. Trees
usually free of the disease should not be sprayed. |
| Yellows |
Twig and trunk growth slows to less
than half that of before infection. Bud break is 1 to 2 weeks
earlier than normal. Foliage appears to be in tufts because
of the very short internodes. Witches brooms may form. Leaves
may be yellow and smaller than normal. Scattered branches die
during the winter. Water sprouts form along branches or at ground
level. Early-fall leaf coloration is a common symptom. Highly
susceptible trees die 1 to 3 years after infection. |
Phytoplasm |
Leafhoppers and spittlebugs are thought
to carry the pathogen. Remove infected trees. |
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