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Final Lab Exam
Downy mildews, Powdery mildews, and Sooty molds
11
Pathology
Undergraduate 4
11/29/2009

Additional Pathology Flashcards

 


 

Cards

Term

Downy Molds

 

Mostly Oomycetes in Peronosporaceae

 

Potato late blight

 

Definition

Phytophthora infestans

Term

Downy Molds

 

Mostly Oomycetes in Peronosporaceae

 

Downy mildew of grapes

 

Definition

Plasmopara viticola

Term

Downy Molds

 

Mostly Oomycetes in Peronosporaceae

 

Plasmopara viticola

 

Definition
  1. Introduced from Americas to Europe
  2. Discovery of Bordeaux mixture (copper sulfate and lime) in 1880's
  3. 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)
Term

Downy Molds

 

Mostly Oomycetes 

 

General Characteristics

 

Definition
  1. Foliage blights
  2. Spores depend on film of water on plant tissues
  3. Prefer cool or warm, but not hot, temperatures
  4. Spores penetrate through stomates or directly
  5. Hyphae intercellular; send haustoria into adjacent cells
  6. Sporangiophores emerge from stomata
  7. Control primarily through protective sprays, such as Metalaxyl, esp. when weather is wet and cool (disease forecasting)
Term

Powdery Mildews

 

Ascomycetes

 

Sexual

Definition
  • Teliomorphs with cleistothecia with appendages and containing 1-3 asci (primarily inoculum in temperate climates)
Term

Powdery Mildews

 

Ascomycetes

 

Asexual

 

Definition
  • Anamorphs Oidium spp. Hyphae superficial, send haustoria into epidermis, but do not penetrate host further. (conidia are secondary inocula)
Term

Powdery Mildews

 

Ascomycetes

 

General Information

 

Definition
  1. Unlike downy mildews, powdery mildews prefer dry weather, spores do not germinate in free water
  2. All are obligate parasites and have narrow host range
Term

Powdery Mildews

 

Ascomycetes

 

Control

 

Definition
  • Because all fungi are superficial, they can be controlled easily with sulfur and certain other fungicides effective against this group of fungi.
Term

Sooty Molds

 

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.
Term

Sooty Molds

 

General Information

Definition
  1. Fungi do not penetrate the host, rather they feed on honeydew
  2. Sooty mold control is contingent upon insect control
Term

Taphrina deformans ("ascomycete") and Exobasidium ("basidiomycete")

 

General Characteristics

 

Definition
  1. Brightly colored, rubbery galls; no necrosis
  2. No asco- or basidiocarp
  3. Requires juvenile tissues, abetted by cool weather
  4. T. deformans causes peach leaf curl
  5.  Exobasidium infects azaleas, blueberries
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