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Chapter Two
Hungry Planet: Stories of Plant Diseases

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Ascomycetes

C2.1. The white powdery growth of hyphae and conidia (asexual spores) of a powdery mildew fungus infecting the surface of a leaf.		C2.2. Conidia of a powdery mildew fungus formed in chains for dispersal.


C2.3. Morels. The surface of a morel is lined with millions of asci, each containing eight ascospores.		C2.4. Numerous asci from a fruiting body of an ascomycete. Each ascus contains eight ascospores. The ascospores have been stained red for visibility (light micrograph).

Basidiomycetes

C2.5. Mushrooms, one with the gills showing under the cap. Basidiospores are produced along the gills.		C2.6. "Turkey tail" fruiting bodies of a fungus that causes a white rot in trees.

Oomycetes

C2.7. A Pythium species producing sporangia and zoospores. A cluster of zoospores has emerged from the empty sporangium (light micrograph).		C2.8. Phytophthora blight of tomatoes. Tomato fruits in direct contact with excessively wet soil are highly vulnerable to infection.


C2.9. Sudden oak death caused by Phytophthora ramorum in Humboldt County, California. Some of the trees are dying, and others have died rapidly with the leaves still on the trees. Several oak species are affected.		C2.10. The underside of a grapevine leaf showing downy mildew. These are the sporangia of the pathogen. Downy mildew develops in moist conditions in the dark.


C2.11. Downy mildew of grape on a young berry. The downy appearance of the hyphae and sporangia give the pathogen its name.		C2.12. Sporangia of a downy mildew pathogen on treelike hyphae. These hyphae emerge from leaf stomata and thus elevate the sporangia above the leaf surface, which aids in the air dispersal of the sporangia (light micrograph).