Term
Downy Molds
Mostly Oomycetes in Peronosporaceae
Potato late blight
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Definition
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Term
Downy Molds
Mostly Oomycetes in Peronosporaceae
Downy mildew of grapes
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Definition
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Term
Downy Molds
Mostly Oomycetes in Peronosporaceae
Plasmopara viticola
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Definition
- Introduced from Americas to Europe
- Discovery of Bordeaux mixture (copper sulfate and lime) in 1880's
- Scenario similar to that of Pierce's diseases, i.e.
- tolerance of native American grapes such as the muscadines (Vitis rotundifolia)
- high susceptibility of European grapes (V. vinifera)
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Term
Downy Molds
Mostly Oomycetes
General Characteristics
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Definition
- Foliage blights
- Spores depend on film of water on plant tissues
- Prefer cool or warm, but not hot, temperatures
- Spores penetrate through stomates or directly
- Hyphae intercellular; send haustoria into adjacent cells
- Sporangiophores emerge from stomata
- Control primarily through protective sprays, such as Metalaxyl, esp. when weather is wet and cool (disease forecasting)
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Term
Powdery Mildews
Ascomycetes
Sexual |
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Definition
- Teliomorphs with cleistothecia with appendages and containing 1-3 asci (primarily inoculum in temperate climates)
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Term
Powdery Mildews
Ascomycetes
Asexual
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Definition
- Anamorphs Oidium spp. Hyphae superficial, send haustoria into epidermis, but do not penetrate host further. (conidia are secondary inocula)
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Term
Powdery Mildews
Ascomycetes
General Information
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Definition
- Unlike downy mildews, powdery mildews prefer dry weather, spores do not germinate in free water
- All are obligate parasites and have narrow host range
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Term
Powdery Mildews
Ascomycetes
Control
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Definition
- Because all fungi are superficial, they can be controlled easily with sulfur and certain other fungicides effective against this group of fungi.
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Term
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Definition
| A complex of ascomycetaceous fungi with dark hyphae that usually are found on the upper leaf surfaces of (mostly) woody plants infested by aphids, scales, whiteflies, and other Homoptera. |
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Term
Sooty Molds
General Information |
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Definition
- Fungi do not penetrate the host, rather they feed on honeydew
- Sooty mold control is contingent upon insect control
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Term
Taphrina deformans ("ascomycete") and Exobasidium ("basidiomycete")
General Characteristics
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Definition
- Brightly colored, rubbery galls; no necrosis
- No asco- or basidiocarp
- Requires juvenile tissues, abetted by cool weather
- T. deformans causes peach leaf curl
- Exobasidium infects azaleas, blueberries
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