1

RNDr. Dana Čížková, CSc.

Czech University of Agriculture Prague

Faculty of Forestry And Environment

Department of Forest Protection And Entomology

F O R E S T P A T H O L O G Y

Contact

• Dana Čížková

• Room number 227

• Tel. num. 224373840

• E-mail cizkova@fld.czu.cz

For a study:

http://www.forestpathology.org/index.html

2

Diesases of the forest-tree species

Causal agents

Diesases induce organisms called a pathogens and vice versa,

a pathogen is an agent that causes disease. Pathogen can be only

living organism such as a bacterium or fungus (virus)

Which of fungi?

According to the way of nourishment we can divide them into three groups:

saprophytic

parasitic

symbiotic

3

• Obligate saprophyte

• decays dead organic matter

• Facultative saprophyte An organism that is usually parasitic but may also lives as a saprophyte

• Obligate parasite: a parasite that can only feed on the living tissues of the host. Does not grow on artificial culture medium.

• Facultative parasite An organism that is usually saprophytic but which under certain conditions may become parasitic e.g. a fungus capable of operating at two trophic modes - decomposer and consumer.

What are fungi?

• Eukaryotic, spore-bearing, heterotrophic

organisms that produce extracellular

enzymes and absorb their nutrition.

4

Spores - a minute propagative unit functioning as a seed, but

differing from it in that a spore does not contain a preformed

embryo

Fruiting body - any complex fungal structure that contains or

bears spores; a sporocarp

Ascomycota: (35 000)

•septate mycelium

•production of endospores (ascospores)

in an ascus

•often dominant asexual reproduction

Basidiomycota: (22 500)

•septate mycelium

•production of exospores

(basidiospores) on a basidium

•production of complex sporocarps

5

Ascomycota (Sac fungi)

Sexual spore

(ascospores)are in

ascus and asci are usually

(but not always)

encased in ascocarps.

Asexual conidiospores

are common.

Ascus

• round to clavate to cylindrical

Bitunicate asci

www.bsu.edu/classes/ruch/msa/geiser.html

www.bsu.edu/classes/ruch/msa/geiser.html

www.mycolog.com/CHAP4a.htm

www.mycolog.com/CHAP4a.htm

www.botany.hawaii.edu/ faculty/wong/Bot201/Ascomycota/

6

Hymenium

• fertile tissue of ascocarp

perithecium- flask-shaped sporocarp

-

www.kki.pl/zenit/grzyby_spyt/ga181.htm

7

Stroma

• stroma: Mass of

fungus hyphae often

including host tissue

containing fruiting-

bodies with spores(pl.

stromata)

8

stroma

stroma

Xylaria hypoxylon

9

Hypoxylon fragiforme

apothecium - cup-shaped sporocarp

10

hysterothecium

hysterothecium

Open hysterothecium with sacs (asci)

11

Ascomycetes may have two distinct reproductive phases

• sexual: with asci and ascospores : Teleomorph

• asexual: with conidia: Anamorph

Ascomycetes classification is based on teleomorphs

Many ascomycetes are known only by their asexual stages.

Deuteromycota, or Fungi imperfecti

Fungi imperfecti (Deuteromycota)

teleomorph Venturia inaequalis anamorph Fusicladium dendriticum

12

Deuteromycota

(Fungi Imperfecti)

• Asexual conidia only, or

mycelium only (mycelia

sterilia).

The Fungi Imperfecti lack a known sexual phase.

Conidium (conidia): Asexual spores

exposed on hyphal stocks.

Pycnidium (Pycnidia): Flask-shaped

organ containing asexual conidia.

Acervulus: Flat pustule containing asexual

conidia.

Basidiomycota

(Club Fungi)

Sexual spores are produced on the ends of club-like hyphae

(basidia). Asexual spores can (but don‘t have to) occur.

•

Basidia are usually located in specialized regions or tissues

(gills or pores)

13

Agaricomycetes

mushrooms, shelf fungi

jelly fungi, coral

crusts, puffballs

Ustilaginomycetes

smuts

Urediniomycetes

rusts

3 Major Classes - of the Basidiomycota

Urediniomycetes (rust fungi)

• To complete the life cyclus very

often need 2 hosts.

Spores:

Aeciospores – in aecia

(pustules) mostly orange or

yellow

Uredospores – in uredia mostly brown

Teliospores – in telia mostly

nearly black

Basidiospores – on basidia

14

Uredinales Chrysomyxa pirolata

aeciospores produced beneath the cone scales of spruce cones

Chrysomyxa pirolata

urediniospores

Orange-yellow urediniospores produced in uredinial pustules

15

Phragmidium mucronatum

teliospores

Gymnosporangium sabinae (pear rust)

• Rust diseases are fungi with alternate hosts. The pear rust alternates between pear trees and Juniperus sabinae.

• On Pears first appear typical leafspot.

• From the leaf spots protrude aecia.These aecia

• bear the asexual aeciospores.

• Spores can be carried long distances in the wind,

• and thus infect nearby junipers

16

Gymnosporangium sabinae

• On Junipers

• On junipers, the rust causes the development of swollen twigs. These swellings are teliospore masses also called telial galls. Telial galls swell up to a few centimetres wide. Teliospores produce the sexual spores on a basidium. These teliospore masses eventually ooze an orange gelatinous substance.

17

Basidiomycetes Agaricomycetes

• Basidioma(ta) is the

formal term used to

designate the

basidiocarp or the

sporocarp (= fruiting

body) of

basidiomycetes

basidiomata are quite

variable in a shape (the

mushroom, puffball,

bracket, etc.)

Disease symptoms

• Necrosis

Tissue death resulting

in scorch, shot

hole or other symptom

of dead tissue:

color changes, necrotic

lesions, wilting, dieback

18

Color changes

Necrotic lesions

19

Damping off necrosis of colar

Necrosis of the bark

20

Exudation

Exudation of

small droplets

honey-yellow or

milky-white ooze

„bleeding canker“

Wilting and drying up

21

Dieback

canker

22

canker

swelling

23

Tumor disease

Witch brooms

24

Twisting

Deformation

25

Disease Control

• Protection

• Exclusion

• Eradication

• Therapy

Disease Control

Protection

• Surface • Precludes a pathogen from contacting a potential host

• Systemic • Introduce a chemical into the host to kill pathogens

attempting to colonize them at some later time

• Silvicultural • Maintain vigorous stands of trees which are better able

to biologically exclude infection from occurring

26

Disease Control

- Exclusion -

• Vector Control • Prevent vectors from attacking potential hosts

• Quarantine • Prevent the spread of disease by not allowing movement

of infected host material into or out of specific areas

• Chemical/biological Treatment

• Fungicidal treatment of potential hosts or habitats, genetic manipulation of hosts or pathogens, culling of diseased stock prior to planting, and “escape” to disease

Disease Control

- Eradication

• Removal of diseased parts or individuals

• Pesticidal (chemical or biological)

treatment • Similar to exclusion – kills pest organism

• Habitat modification • Removal of bark to kill vectors or dessicate pests,

fumigation of soil or plant parts, dormant sprays of trees,

destruction of infected host material by fire or other

treatment, etc.

27

Disease Control

- Therapy -

• Generally involves the use of systemic selective

chemicals - chemicals which are pest selective

and host neutral or beneficial

• Physical or Environmental Methods - removal of

an environmental element which is leading to

disease or damage

28

Black rot-mummification of acorns Ciboria batschiana

Black rot-mummification of acorns

• Ciboria batschina is the fungus

(Ascomycota) causing black rot-mummification of acorns of Quercus spp. Ciboria spreads from affected fruits to unaffected acorns even at low temperatures (-1 °C), thus entire acorn crop may be destroyed during the first winter storage. Ascospores of the fungus can quickly infect acorn after they fall to the forest floor in the autumn, but also acorns on the trees can be infected. The only effective control of black rot is hot water treatment (thermotherapy - max. 42 °C for 10 hours or 46 °C for 4 hours) of acorns which kills the fungus, but not acorns. Also, if acorns are infected mainly after their fall to the forest floor the use of net suspended above the floor could decrease or prevent acorn infection.

29

Damping off

• Damping-off is a disease of

germinating seeds and seedlings

caused primarily by fungi. The entire

seed may decay before germination or

the seedling may rot just below the soil

line. Healthy appearing plants selected

from flats with damping-off may

develop root rot or stem canker

several weeks later. With some

damping-off fungi, foliar blight may

also occur. Pythium, Fusarium,

Phytophthora, Rhizoctonia and

Alternaria are fungi that commonly

cause damping-off. There are many

other species of fungi that occasionally

cause this disease.

30

Botrytis cinerea

grey mold

• Forestry harmful especially in nursery plants important for the spread is stable high air humidity attacks all species of trees, likes its ground after frost damage is capable of spreading even at temperatures around 0 ° C, humidity of about 95% at 85% conidia don‘t germination.

31

Phytophthora cactorum

Crown rot Phytophthora cactorum

Phytophthora cactorum is a fungal disease that can infect

both the roots and the above ground parts of the deciduous

trees seedlings, especially of beech.

32

Lophodermium needle-cast

• The name "needle cast" refers to a condition in coniferous trees where a sudden, severe loss of needles occurs. Lophodermium pinastri is the commonest fungus attacking the needles of pine. Symptoms: Brown spots, often with yellow margins, appear on the needles in the autumn. As the spots enlarge, the needles begin to yellow, then turn brown, and die by late spring or early summer. Later in the season on the fallen needles appear grayish-black, navicula -shaped fruiting bodies noticeable on all sides of the needles. These fruiting structures swell in wet weather, split down the center, and eject their ascospores.

33

Powdery mildew on oak, (or oak mildew) is caused by the

ascomycete fungus Microsphaera alphitoides.

• During the initial stages of infection small chlorotic spots develop on the upper surface of young leaves and shoots. Grey-white patches of mycelium become visible on the leaves as the fungus spreads within its host's tissues. As the patches grow, they converge into larger patches on both the upper and lower leaf surface, and may eventually cover most of the leaf surface area. The conidia formed on the mycelium contribute to its powdery appearance. If and when cleistothecia are formed they can be seen with the naked eye.