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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

dead petioles produces apothecia sexual stages -

Hymenoscyphus pseudoalbidus producing ascospores -

June to September (October), which are carried by the wind

and infect host

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Chalara fraxinea

Hymenoscyphus pseudoalbidus

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Foto: L. Havrdová

Symptoms of damage

• On leaves and petioles dark brown necrosis, premature

leaf fall (in late summer) to complete defoliation of the

tree.

Drying and dying of annual herbaceous terminal

shoots.

Elliptical, sunken necrosis often with a sharp transition

between the dead and the living part of the tissue.

Production of substitute shoots under dead parts of

branches and gradually cluster of foliage around the

skeletal branches.

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On leaves and petioles dark brown necrosis, premature leaf fall.

Foto: L. Havrdová

Foto: L. Havrdová

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Drying and dying of annual

herbaceous terminal shoots.

Necrosis, often with a sharp

transition between the dead and

the living part.

Foto: L. Havrdová

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Cluster of foliage around the skeletal branches

Foto: L. Havrdová

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Decline of alder

(Phytophthora alni ) Most affected ecosystems by Phytophthora alni are riparian vegetation

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Description of the species

Phytophthora alni is the invading parasite with

crucial impact on riparian and potentially forests

of alders. The infected alder in one year or

several years die or are seriously damaged.

Wasting disease usually occurs in outbreaks,

typical symptoms are the bases strains

(necrosis, exudates). The pathogen infects the

roots of alder and the collar, most often found in

riparian vegetation with a higher level of ground

water.

Phytophthora alni

zoosporangium

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Symptoms of damage

• Existence outbreaks of declining trees or groups of

trees or individual .

Thinning crowns in the whole volume, a significant

reduction and chlorotization leaves.

Rusty, reddish to black exudates on the bark or in

cracks of bark on the base of trees.

Tongue like reddish to brown necrosis of vascular

tissue under the bark .

Sunken, wound occlusion tongue like damage at

base of tree,sometimes covered with cracked bark.

Root rot (non-specific symptom)

discharges pigments in bark

cracks

red-brown vascular tissue necrosis on

the basis of trunk

Foto: K. Černý

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damaged bases covered

cracked bark

rot roots, dead roots

erosion, bank

erosion

Foto: K. Černý

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Foto: K. Černý

Break-up of wetland with alders

Fire Blight Erwinia amylovora

• This blight is typified by a

sudden death of leaves

and stems. These parts

die, turn black, and the

woody parts develop

cankers. Twigs often

looks like they have been

scorched with fire.

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Fire Blight Erwinia amylovora

• The bacteria, if en

masse, appear like an

honey coloured ooze.

Chestnut blight or canker

Cryphonectria parasitica - Symptoms

• Drying of the crown (sudden drying of in

June)

Symptomatic confusion with frost damage,

extreme drought and ink disease

(Phytophthora cambivora, Phytophthora

cinnamomii)

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Chestnut blight or canker

Cryphonectria parasitica

Chestnut blight or canker

Cryphonectria parasitica

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Cryphonectria parasitica

Cryphonectria parasitica

stroma

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Cryphonectria parasitica

pyknids

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Cryphonectria parasitica

Cryphonectria parasitica