Symptoms
of Annosum Root Rot
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Trees show sparse foliage
(in the crown), tufted needles
(needles chiefly on the tips of the
twig rather than along most of its
length), chlorosis to some degree,
and necrosis (mortality) of the tree.
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Mortality usually occurs in pockets or
small groups of trees which allows sunlight to impact on the forest floor.
This picture shows typical regeneration of pine in an area or disease
focus of Annosum Root Rot. This can create pockets or small
areas up to 1/2 an acre in size of young
trees, thus an uneven aged
stand.
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Windthrow is a common
symptom. |
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Large trees are windthrown due to the
large anchor roots being decayed by Heterobasidion annosum.
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Stimulation of resin production in
roots is common, causing soil to adhere to them. The
internal portion of roots can also have a
wet, pitch-soaked appearance.
An internal discoloration is often
seen in the lower trunk portion of the infected tree prior to decay.
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Signs
of Annosum Root Rot
Basidiocarps (fruit bodies, sporocarps, conks)
of Heterobasidion annosum are sexual
reproductive structures in which basidiospores
are produced. Note where the
basidiocarps are formed on the infected tree
or stump.
When fresh, basidiocarps of Heterobasidion
annosum are tan on top with a cream color margin
and a cream color on the underside where
the pores are produced. The hymenium, basidia
and basidiospores are located on the inner
walls of the pores.
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Spread
of Annosum Root Rot
Local or short distance spread is by hyphae
(mycelium) through root contact or root grafts
of an infected root and a healthy root.
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Excavated pine roots showing
the extent of the roots in a pine plantation.
The opportunity for
root contact and/or root grafts
is quite high. |
This eastern red cedar became infected and
died as a result of root contact with an infected
nearby pine. The pine stump can be
seen (circled) to the lower left of the dead cedar.
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Long distance (up to a mile or so)
spread is by windblown basidiospores that most commonly infect freshly
cut stumps. Basal wounds are also infection courts.
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Management
and Control of Annosum Root Rot
Image Source: USDA.
1977. Fomes Annosus Root Rot in the South; Guidelines for Prevention.
Hazard areas have been mapped in the southeastern
U.S. and should be used in management
plans. These high hazard sites should
be avoided as far as pine management is concerned.
Image Source: USDA.
1977. Fomes Annosus Root Rot in the South; Guidelines for Prevention.
Stump surfaces in the summer attain high temperatures
that are lethal to any basidiospores that
land on them. Typically, these lethal temperatures
are attained south of the 34° parallel.
????
What does this information
tell you about time (season) of cutting?
????
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Stump surfaces may be treated with several
chemicals to prevent infection. Borax is one such effective compound.
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Biological control is another management
technique. Phlebiopsis (Peniophora) gigantea can be applied
to a freshly cut stump surface to prevent infection.
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There are a number of other management and
control practices recommended.
Consult your laboratory manual or appropriate
literature.
????
What are some of the other
practices?
????
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Armillaria
(Shoestring) Root Rot
Symptoms
of Armillaria Root Rot
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Pine is often killed on sites where Armillaria
is present. This is especially true in the northwestern U.S. More
mature pines are also affected.
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In central and eastern U.S. hardwoods
are the primary hosts and typically display dieback symptoms, sparse crowns
and branch and trunk sprouts.
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Young plants, both conifers and hardwoods
can be girdled causing mortality as
a result of necrosis of the bark, cambium
and sapwood.
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Older trees may have significant
heartrot and frequently break.
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Signs
of Armillaria Root Rot
Mycelial fans of Armillaria species
appear as white fan-like sheets beneath the bark of infected trees.
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Black rhizomorphs are produced beneath
the bark and on the surface of roots. These structures can grow through
the soil considerable distances and infect roots of nearby healthy trees.
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Basidiocarps of two Armillaria
species. Note the habitat (usually on stumps or trunks or at the base of
infected trees) and habit (fruiting in clusters).
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Until recently most populations of Armillaria
were classified as one species: Armillaria mellea. We now recognize
several species (up to 12 according to some taxonomists) some of which
apparently are more aggressive in causing disease than others. There are
five species of Armillaria that have been found in North Carolina
(four are pictured below). There may be additional species found as studies
continue.
Armillaria tabescens
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Armillaria gallica
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Armillaria ostoyea
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Armillaria mellea
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Spread
of Armillaria
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Local spread is by rhizomorphs from root
to root through soil. Spread within a tree is by mycelium and mycelial
fans. Long distance dispersal is by windblown basidiospores.
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Acknowledgements:
Several slides were provided
by Dr. James Worrall, SUNY
College, Syracuse University,
and Dr. Terry Shaw, USFS.
Their donations are gratefully appreciated.
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This website was prepared by Meredith Boyd
and Becky Bernard.
Last updated on 04 February 2008 by M.J. Munster
