Sudden oak deathPhytophthora ramorum

Sudden oak deathPhytophthora ramorum

Sudden oak deathPhytophthora ramorum

Black pod disease of cacao

P. megakarya

P. capsici

P. palmivora

Downy Mildew - GrapePlasmopora viticolaObligate biotrophic pathogenPhotosynthetic area lostFruit yield reduced & Fruit rot

Downy Mildew: Symptoms and Signs

Leaf spots are yellowish on upper surface, white and downy on lower surface.Late-season infection results in a mosaic of yellow, red, and brown angular spots.

Early symptoms

Late symptoms

Signs

Downy Mildew: Symptoms and Signs

Diseased fruit are off-color,shrivel and become coveredwith white, downy hyphalgrowth.

Downy Mildew of Grape

Sporangia

Downy MildewPlasmopara viticola

•Source of secondary inoculum•Inoculum to new leaves and fruit

Dew and rain contributes to durationof leaf wetness

Downy Mildew of cucurbitsPseudoperonospora cubensis

Downy mildew of corn -Sclerophthora macrospora

Downy mildew of sugar cane – Peronosclerospora sacchari

Oomycetes: Aphanomyces

SporesSporangiophore

Oomycetes: Aphanomyces

Exit pore

OomycetesAphanomyces

• Sporangium is a modified hypha

• Primary spores exit and aggregate at end of sporangium

• Primary spores release zoospores

Spores

Sporangiophore

OomycetesAphanomyces

• Primary spores• Two means to

resume growth– Germinate to

germ tube– Release

zoospore through pore

Exit pore

Albugo candida

Chytridiomycota – “chytrids”

• Simple fungi• Produce motile

spores• Mostly saprobes and

parasites in aquatic habitats

• Could just as well be Protists

Fig 31.5 Chytridium growing on spores

Part of a grass root with large sporangia (sp) of Olpidium brassicae within the root cells. At maturity the sporangia release zoospores through exit tubes (et). Several zoospore cysts (cy) can be seen on the root.

(a) Zoospore cysts have germinated to produce short tubes that penetrated the root cell wall then released the cyst content as a naked protoplast into the host cell. Stellate resting spores seen in early stages of development (b) and in mature form (c).

Potato wart - Synchytrium endobioticum

E. Çakır

Zygomycota – “zygote fungi”

• Sex - zygosporangia• Asex - common• Hyphae have no cross

walls• Grow rapidly

• Mycorrhizae

Fig 31.6 Rhizopus on strawberries

•Rhizopus fruit rot

•Conidia •Ascospore

•Asexual Spores •Sexual Spores

Ascomycete Spores

• Ascocarp = fruiting body containing ascospores in asci

• Ascospore = sexual spore• Ascus (asci) = ‘sack’ containing 8

ascospores

Ascus

hyaline colored

• No Ascocarp• Cleistothecium• Perithecium(pseudothecium or

pseudoperithecium)

• Apothecium

• http://vegetablemdonline.ppath.cornell.edu/NewsArticles/Cuc_Downy.htm

http://vegetablemdonline.ppath.cornell.edu/factsheets/Onions_Downy.htm#Click