Canker Stain
of Sycamore and London Plane
London plane and sycamore trees are susceptible to
a fungus, Ceratocystis fimbriata
f. sp. platani, which is lethal.
The living cells of the wood in the phloem, cambium, and sapwood
are invaded quickly soon after a fresh wound exposes those cells.
Although sap-feeding insects can carry the fungus from tree to tree
naturally, the most severe outbreaks are usually traced to pruning
and other work on the trees.
Symptoms
Infected sycamore and London planes have sparse foliage, small leaves,
and elongated sunken cankers on the trunk and larger branches. The
canker may at first just appear to be a darkened, flattened area
on the wood. Beneath the cankers, the wood is stained bluish black
or reddish brown in a wedge-shape (when viewed in cross section)
with the point of the wedge extending toward the center of the trunk
or branch. As the disease progresses and cankers enlarge, water
sprouts develop below the cankers. These are killed. Large trees
may take several years to be killed, but pole-sized trees may die
within 2 years.
Life History
The fungus enters only through fresh wounds. Infection is least
likely to occur in December and January. Once disease begins, secondary
wood-rotting fungi frequently invade the cankers and cause severe
additional damage. The fungus produces spores within days of the
first infection. Black fungal fruiting structures form on the wound
surface and produce slimy masses of spores.The spores ready stick
to pruning tools, ropes, ladders, paint brushes used for applying
wound dressings, and other equipment.
Management
It is very important to disinfest all tools and equipment immediately
after use on a sycamore or London plane tree and before proceeding
to another such tree. Do not use wound paints on these trees since
contaminated brushes efficiently move spores from tree to tree.
Prune sycamores and London planes only during December and January
when the weather is dry. When a tree is found to be infected, remove
it. No chemicals effectively control this disease.
|
