1. Images and lecture material were not entirely created by J. Bond
** Images and lecture material were not entirely created by J. Bond. Some of this material was created by others.**

5. Rhizopus sp. on peach
Rhizopus sp. on sunflower

6. Plant Pathology – G.N. Agrios

7. TRUE FUNGI ASCOMYCETES - called the sac fungi because
sexual spores (ascospores) are produced in
a sac (ascus).
This is the largest group of fungi (35k +)
with the most economically important members.

8. ASCOMYCETES Characteristics :
1. Most are facultative parasites - they can survive in soil or plant debris, often for several years. A few are obligate parasites.
2. They produce a cellular hyphae (i.e., with distinct cell cross walls).
3. They produce a stroma - a mass of hyphae in which fruiting bodies are produced.
4. Sexual spores = ascospores. They are produced in groups of 8, which are enclosed in a single ascus (asci).
5. Ascospores in asci are produced in an ascocarp.
There are several basic types of ascocarps, but each fungus produces only one type:

9. Plant Pathology – G.N. Agrios

10. Ascocarps
a. Naked - asci are produced exposed on a plant surface, i.e., not in an ascocarp.
Ex: Taphrina deformans - peach leaf curl
Ex: Saccharomyces spp. - the yeasts

11. Naked - asci

12. Ascocarps
a. Naked - asci are produced exposed on a plant surface, i.e., not in an ascocarp.
b. Cleistothecia - asci are produced in a completely closed spherical structure.
Ex: Sphaerotheca pannosa - powdery mildew of rose
Ex: Erysiphe graminis - powdery mildew of wheat
Plant Pathology – G.N. Agrios

13. Cleistothecia APS Slide Collection APS Slide Collection

14. Ascocarps Ex: Claviceps purpurea - ergot of grains
a. Naked - asci are produced exposed on a plant surface, i.e., not in an ascocarp.
b. Cleistothecia - asci are produced in a completely closed spherical structure.
c. Perithecia - asci are produced in a nearly-completely closed structure with a single opening and a distinct wall. Perithecia can be round or some version of flask-shaped.
Ex: Claviceps purpurea - ergot of grains
Ex: Ophiostoma ulmi - Dutch elm disease
Ex: Cryphonectria parasitica - chestnut blight
Plant Pathology – G.N. Agrios

15. Perithecia
APS Slide Collection
APS Slide Collection

16. Ascocarps
a. Naked - asci are produced exposed on a plant surface, i.e., not in an ascocarp.
b. Cleistothecia - asci are produced in a completely closed spherical structure.
c. Perithecia - asci are produced in a nearly-completely closed structure with a single opening and a distinct wall. Perithecia can be round or some version of flask-shaped.
d. Apothecia - asci are produced in an open cup- or saucer-shaped structure.
Ex: Monilina fructicola – brown rot of stone fruits
Ex: Sclerotinia sclerotiorum - white mold of bean
Plant Pathology – G.N. Agrios

17. Apothecia
APS Slide Collection
APS Slide Collection

18. Ascocarps
Naked - asci are produced exposed on a plant surface
Cleistothecia - asci are produced in a completely closed spherical structure.
Perithecia - asci are produced in a nearly-completely closed structure with a single opening. Perithecia can be round or some version of flask-shaped.
Apothecia - asci are produced in an open cup- or saucer-shaped structure.
Pseudothecia (aka ascostroma) - asci are produced in cavities without a distinct wall within a stroma of mycelium within host tissues.
Ex: Venturia inaequalis - apple scab
Ex: Guignardia bidwellii - black rot of grape
Plant Pathology – G.N. Agrios

19. Pseudothecia
APS Slide Collection
APS Slide Collection

20. Ascocarps
Naked - asci are produced exposed on a plant surface
Cleistothecia - asci are produced in a completely closed spherical structure.
Perithecia - asci are produced in a nearly-completely closed structure with a distinct wall with a single opening. Perithecia can be round or some version of flask-shaped.
Apothecia - asci are produced in an open cup- or saucer-shaped structure.
Pseudothecia (aka ascostroma) - asci are produced in cavities without a distinct wall within a stroma of mycelium produced within host tissues.

21. Teleomorph vs Anamorph
The teleomorph (perfect stage) is the sexual stage
The anamorph (imperfect stage) is the asexual stage
APS Slide Collection
APS Slide Collection
Nectria - perithecia
Fusarium - conidia