Sudden oak death Phytophthora ramorum Sudden oak death Phytophthora ramorum

Sudden oak death Phytophthora ramorum

Black pod disease of cacao P. megakarya P. capsici P. palmivora

Downy Mildew - Grape Plasmopora viticola Obligate biotrophic pathogen Photosynthetic area lost Fruit 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 covered with white, downy hyphal growth.

Downy Mildew of Grape Sporangia Downy Mildew Plasmopara viticola Source of secondary inoculum Inoculum to new leaves and fruit

Dew and rain contributes to duration of leaf wetness

Downy Mildew of cucurbits Pseudoperonospora cubensis

Downy mildew of corn -Sclerophthora macrospora

Downy mildew of sugar cane – Peronosclerospora sacchari

Oomycetes: Aphanomyces Spores Sporangiophore

Oomycetes: Aphanomyces Exit pore

Oomycetes Aphanomyces Sporangium is a modified hypha Primary spores exit and aggregate at end of sporangium Primary spores release zoospores Spores Sporangiophore

Oomycetes Aphanomyces 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

ConidiaAscospore Asexual SporesSexual 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 pseudoperitheciu m) Apothecium

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