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

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Presentation on theme: "** Images and lecture material were not entirely created by J. Bond. Some of this material was created by others.**"— Presentation transcript:

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

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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

14 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. 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

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

18 Ascocarps a.Naked - asci are produced exposed on a plant surface 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. Perithecia can be round or some version of flask-shaped. d.Apothecia - asci are produced in an open cup- or saucer-shaped structure. e.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

20 Ascocarps a.Naked - asci are produced exposed on a plant surface b.Cleistothecia - asci are produced in a completely closed spherical structure. c.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. d.Apothecia - asci are produced in an open cup- or saucer- shaped structure. e.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 Nectriaperithecia Nectria - perithecia Fusariumconidia Fusarium - conidia APS Slide Collection


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