Ascomycetes cont. Review Peach leaf curl – Taphrina deformansPeach leaf curl – Taphrina deformans Leaf blister on oaks – Taphrina caerulescens Powdery mildew of rose – Sphaerotheca pannosaPowdery mildew of rose – Sphaerotheca pannosa Ergot of rye – Claviceps purpureaErgot of rye – Claviceps purpureaToday Brown rot of stone fruit – Monilinia fructicolaBrown rot of stone fruit – Monilinia fructicola Nectria canker of apple and other trees – Nectria cinnabarinaNectria canker of apple and other trees – Nectria cinnabarina Dutch elm disease – Ophiostoma novo-ulmiDutch elm disease – Ophiostoma novo-ulmi

Brown Rot of Stone Fruit Teleomorph: Sclerotinia fructicola Anamorph: Monilinia fructicola

Brown rot of stone fruit One of the most important disease of stone fruit Greatly influenced weather A fruit disease but can cause blossom blight and twig blight Fungal penetration of fruit can result in latent infection that develops only after the fruit has ripened

Fungus overwinters in twigs/buds/mummies

Nectria canker of apple Nectria cinnabarina

Important disease of fruit and forest trees Results in cankers that can reduce vigor or kill small trees Cankers can produce sexual and asexual spores every year Control by pruning and using dormant spray afterwards Produces sexual spores in perithecia and asexual spores on sporodochia

Dutch elm disease Introduced in the US in 1930’s By 1973, had spread to the east and west coasts

Dutch elm disease Ophiostoma novo-ulmi Affects all elm species but is particularly severe on American elm Death of tree may occur in weeks or years A heterothallic fungus – require strains of opposite mating types Two types of asexual conidia produced as well as sexual spores Infect plant xylem and clogs the conductive tissue with gels, gums, tyloses, and fungal tissue

Insect-vectored disease Fungus inhabits galleries of the European and American elm bark beetles Produces sticky spores in the galleries and at the gallery exits. When mature beetles exit to find new trees, they are covered with fungus spores The spores are deposited in the wounds at the beetle feeding sites

Ascomycetes Sexual Spores (Ascospores) by: 1) Free, independent asci 2) Apothecia 3) Cleistothecia 4) Perithecia 5) Pseudothecia Sporocarps

Fungi Imperfecti -Imperfect (aka asexual-only) fungi. Many fungi produce only asexual stages. -These fungi are those that may have lost the need to produce sexual spores, or for which no sexual state has yet been identified. This is a problem, because fungal identification is based on production of sexual spores. If no sexual stage, then what? Answer = artificial group (Deuteromycetes). Within this artificial group, there is classification based on conidia production.

Deuteromycetes (Fungi Imperfecti) Asexual stages of many Ascomycetes and some BasidiomycetesAsexual stages of many Ascomycetes and some Basidiomycetes Causes many important diseasesCauses many important diseases Often the secondary disease cycleOften the secondary disease cycle Spore stage is conidiaSpore stage is conidia

Deuteromycetes Asexual Reproduction – Conidia –Free, and independent –Synnema –Acervulus –Sporodochium –Pycnidium

If fungi produce no known spores, they are grouped in the "Mycelia Sterilia" or sterile mycelia. Ex: Sclerotium, Rhizoctonia Fungal nomenclature: This means that a given fungus can be assigned one Genus name for the sexual stage and another for the asexual stage. However the sexual stage is always the correct name.

What happens if you have an imperfect fungus, work on it for years and call it by its imperfect name, then someone discovers the sexual stage and renames it? From then on, the fungus must be officially referred to by the sexual name. But often both names are kept, especially if there is a large body of literature under the old name. Then you'll see reference to sexual name (= teleomorph, i.e., married name) first followed by asexual name (= anamorph, i.e., maiden name) in parentheses. Ex: Rhizoctonia solani / Thanatephorus cucumeris Thanatephorus cucumeris (anamorph Rhizoctonia solani)

Sometimes its much easier. If a fungus is first identified by the sexual stage, then Genus names for the asexual stages are not used. Ex: Cryphonectria parasitica is the teleomorph. The asexual spore is produced in a pycnidium, but the pycnidial stage is never identified with a name. It is referred to as the pycnidial stage of the chestnut blight fungus. Ex: Ophiostoma ulmi produces 2 asexual stages - Graphium stage, Cephalosporium stage. Most imperfect fungi have perfect stages that are in Ascomycetes. A few (ca. 25 or so) are Zygomycetes or Oomycetes, and fewer still are Basidiomycetes.