3/31/2014 1 white pine blister rust Cronartium ribicola • Blister rust is a fungus with a complex life cycle. A fungus growing on blackcurrents, and other Ribes species, releases first uredospores during the growing season. At the end of summer teliospores are created and the next spring basidiospores. These spores infect white pine, where they grow as fungal mycelia in the cambium of the pine host. Later in the year yellowing blisters, and cankers, develop on the white pine stems. These blisters release aeciospores which re-infect blackcurrents. Cronartium ribicola Cronartium ribicola canker with resinosis in mid-summer, after aeciospore release aeciospores
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white pine blister rust Cronartium ribicola
• Blister rust is a fungus with a complex life cycle. A fungus growing on blackcurrents, and other Ribes species, releases first uredospores during the growing season. At the end of summer teliospores are created and the next spring basidiospores. These spores infect white pine, where they grow as fungal mycelia in the cambium of the pine host. Later in the year yellowing blisters, and cankers, develop on the white pine stems. These blisters release aeciospores which re-infect blackcurrents.
Cronartium ribicola
Cronartium ribicola canker with
resinosis in mid-summer, after
aeciospore release
aeciospores
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Cronartium ribicola
Cronartium ribicola
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Cronartium ribicola
Pine needle rusts Coleosporium spp.
• Needle rust is most prevalent on young
trees. The disease usually does not
seriously damage trees, and is of most
concern in Christmas tree plantings and
nurseries. Most two- and three-needle
pines are susceptible. Goldenrod, asters,
and other plants serve as the alternate
hosts.
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Pine needle rusts Coleosporium spp • Symptoms: In late spring, small
white pustules filled with bright orange spores develop on discolored patches on either side of infected second-year needles. These disappear by the end of summer, after the aeciospores are cast, leaving inconspicuous yellow-brown flecks on the needles; heavily infected needles are cast. Aeciospores infect the alternate host - this rust fungus needs two different hosts to complete its life cycle. Senecio, Tussilago and goldenrod are infected early in the summer, and orange, cushion-like masses (uredospores) develop on the underside of their leaves. These spores reinfect the alternate host, but not the pine. Later in the summer telia form on the leaves. These produce orange-yellow spores on which basidia form. Basidiospores infect current-year pine needles, where the fungus overwinters.
Pine needle rusts Coleosporium spp.
Yellow-orange fissures develop
in late spring on infected needles.
Mature aecia on needles
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Pine needle rusts Coleosporium
Pine needle rusts Coleosporium spp.
Uredia on Senecio
on eyebright
Uredospores
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Pine twisting rust Melampsora pinitorqua
Sporulating infection (aeciospores) of M. pinitorqua on a growing pine shoot
Distorted shoot after numerous infections
Fir broom rust Melampsorella caryophyllacearum
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• This rust is easily recognized by the conspicuous perennial, systemic brooms formed on branches throughout the crown. Infected twigs in the brooms are shorter, thicker and chlorotic than normal. At the base of the broom, infected branches and stems are swollen, forming an elongate canker or gall. Stem swellings may be observed after brooms have died and are shed.
Cenangium limb cancer (Cenangium
ferruginosum)
• The disease has several diagnostic
features. A sharp boundary between
brown, dead bark and living tissue exists.
Needles brown from the bases toward the
tips and are often cast during the summer
after the affected branch has died. Little or
no resin is produced on infected
tissue.Drying of branches in the crown
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Cenangium limb cancer (Cenangium
ferruginosum)
Brunchorstia disease
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Ascocalyx abietina (Brunchorstia pinea)
• Early signs of a Brunchorstia disease
infection includes a purple tint in the
needles and, more evidently the browning
and the falling off the needles in the wrong
season. Fungus kills the buds on the
affected shoot. The infection spreads
along the shoot, which turns greenish
yellow and dies.
Ascocalyx abietina (Brunchorstia pinea)
orange needle bases, found in May and June
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Ascocalyx abietina (Brunchorstia pinea)
Ascocalyx abietina (Brunchorstia pinea)
Pycnides
Conidies
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Red band needle blight Mycosphaerella pini
Red band needle blight Mycosphaerella pini
• The most characteristic feature of this disease are the reddish bands that encircle the needles. These bands begin as small chlorotic bands or spots in the fall. Needle tissue beyond the chlorotic areas loses color two or three weeks after infection.
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• Fruiting structures
develop beneath the
needle surface in the
center of these bands
as small black bodies
that enlarge and
rupture the needle
epidermis.
• (Dothistroma
septospora) Acervuli on dead needle
• As infection ages into the second year, these spots turn distinctly brown and enlarge to produce characteristic red bands around the needles. Both brown and reddish discoloration can be seen on green needles, but the reddish areas are most distinct on needles that are dead or recently cast. Infection usually begins in the lower crown and on older needles. Current-year needles are not susceptible to infection until midsummer, but second-year and older needles are susceptible throughout the year.
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Needle cast Meloderma desmazieresii
on Pinus strobus
Needle cast on Spruce
• Lophodermium
piceae • first signs are reddish spots,
stripes on the green needles,
gradually turn brown,
transverse black stripes, and
finally pycnidium - fruiting
bodies. Under normal
circumstances, infects only
the oldest year of needles.
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• Lirula macrospora
• On the brown needles in
October and July of next
year develops fruiting
body, which ripen in April
next year when the
infection occurs on new
needles. Attacked all the
needles of the same year.
It occurs at lower altitudes
on younger spruce, in
humid mountainous areas
also on old trees
Douglas-fir needlecast Rhabdocline
pseudotsugae
• Chlorotic, yellow spots 1-2 mm in diameter appear on both surfaces of 1st year needles in the fall, coalescing and darkening to red-brown during the winter. Some needles are shed during the winter.
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• On needles that are retained, fruiting bodies (apothecia) form in the late spring. Apothecia are small, orange-brown, raised pustules, generally occurring on the lower side but occasionally on the upper side of needles.
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Rhabdocline pseudotsugae
• Repeated severe infection almost completely defoliates trees, leaving only the current years needles. The impact of the disease therefore, is greatest on small trees because of their smaller total number of needles; large trees usually undergo only light defoliation and sustain little damage. Christmas tree plantations can be severely damaged.
Swiss needle cast of Douglas-fir
Phaeocryptopus gaeumannii
Infected foliage on right and healthy foliage on left
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Swiss needle cast of Douglas-fir
Phaeocryptopus gaeumannii
• Phaeocryptopus gaeumannii is a foliar
fungal pathogen that causes the disease
Swiss needle cast of Douglas-fir. It infects
and fruits through stomata. It causes
needles to turn yellow and fall prematurely
from the tree, ultimately reducing tree
growth and survival. Tree mortality is rare,
occurring only after many years of
defoliation.
Phaeocryptopus gaeumannii
Necrotic lesions on needles 2 years old and older; dieback from the tip of needle.
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Phaeocryptopus gaeumannii
Fruiting bodies
close-up view of infected needle Fruiting bodies
Micrograph of needle cross section with
pseudothecia emerging
from stomata on underside.
Diplodia tip blight Sphaeropsis sapinea
Austrian pine, ponderosa pine, Scots pine and mugo pine
Severely infected tree Close-up of infected twig
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• Browning, stunting, and
twisting of new shoots
and needles are the first
symptoms. One side of a
tree or the lower part may
be the first area affected.
During wet springs, every
branch may have brown
tips. A brown
discoloration starts at the
base of needles and
grows toward the tip.
• Needles die by the
time they are one half
to three fourths
normal length.
Sometimes needles
curl and twist.
Infected stems often
result in droopy
candles (new growth).
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• Resinous cankers may
appear on stems at the
youngest branch whorl or
base of blighted needles.
Resin from infected areas
may cause dead needles
to stick to the tree. Large
resinous cankers may
occur on older branches
where wounds occur.
Winter injury is a common
site of branch infection.
Main stem infection of Sphaeropsis sapinea on red pine. Bark has been peeled
back to expose dark discoloration of canker face.
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Diplodia blight Sphaeropsis sapinea
Fruiting bodies. Pycnidia on twig
Diplodia blight Sphaeropsis sapinea
Black spots (pyknidia) on the scales of pine cones
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European larch canker Lachnellula
willkommii
• Symptoms: The
cracks in the bark,
cankers and
small,cup-like orange
fruiting bodies
(apothecia) on
affeceted tissue.
Nectria canker (Nectria galligena)
• Nectria canker initially appears as a slightly sunken, elongated lesion. The surface of the outer bark is often discoloured and may be open or covered with bark. Attempts by the tree to contain the infection result in the formation of a callus ridge during the growing season. If the tree is not successful, the fungus will reinfect healthy wood beyond the callus ridge the following year. As a result, perennial cankers develop a target-like appearance, due to the alternation of fungal growth and the production of callus tissue by the tree. Eventually, branch dieback or death of the tree may occur if branches or the trunk are girdled by the fungus. Cankered trees are vulnerable to windthrow, commonly breaking at the canker site.
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• In spring and early summer, pink or cream colored, cushion-like reproductive structures (sporodochia) form on the surface of tissue infected the previous year. Other reproductive structures, perithecia, are formed in late summer to early fall. These structures are initially red coloured, later turning brown.
Anamorfa (pink) Cylindrocarpon mali
Teleomorfa (scarlet)
Neonectria galligena
Neonectria galligena
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Nectria canker
Taphrina betulina
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Damage is
caused by the
formation of
tyloses in the
vascular system
of the host plant
which restricts
the flow of
needed water
and nutrients
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Vascular wilts
• Dutch elm disease
Dutch Elm Disease - Why “Dutch”? First
isolated in 1920 by a
Dr. Schwarz in the
Netherlands.
- Wilt disease that
attacks elm (Ulmus ssp);
caused by ascomycete
fungus (Ophiostoma ulmi
and O. novo-ulmi),
formerly (Ceratosystis) with
anamorpha Pesotum ulmi.
.
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Dutch elm disease
•Ophiostoma ulmi
•Pesotum ulmi
Vectors of disease
• Insects: 1) the native elm beetle 2) the smaller
European elm beetle. The beetles can fly for
several miles, allowing the disease to spread
over a wide area.
• Root grafts: when elms are within 50 feet of one
another, their roots can grow together and
disease passes easily along. Important in urban
settings.
• Infected logs: Often transferred long distances in
logs.
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Gallery of the
European elm bark
beetle, one vector
of the Dutch elm
disease fungus, on
the inner bark of an
elm
Dutch elm disease
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Streaking of the xylem is a common symptom of
vascular wilt diseases
Dutch elm disease
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Tar spot Rhytisma acerinum
stroma
• Oval or irregular-
shaped yellowish-
green spots on the
upper surface of
leaves are the first
sign of the disease.
These spots spread
and become raised,
then blacken over
time (stroma).
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Rhytisma acerinum
• The fungus
overwinters in the
black tarry spots on
the dead leaves that
fall in autumn. In
spring, the fungus
produces spores that
spread to young
maple leaves causing
new infections.
Necrosis of ash Chalara fraxinea
• On the hyphae in a culture creates sporangiofors producing
conidia.
Mycelium of the pathogen survives in infected shoots of
winter, after the onset of higher temperatures, especially on