Late blight caused by Phytophthora infestans

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Late blight caused by Phytophthora infestans
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Tubers infected with P. infestans
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Late blight of Potatoes (Phytophthora
infestans)
(Image courtesy of The American Phytopathological
Society)
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Late blighted potato tubers
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Evictions
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View of test field - Hancock Research Station
1994
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Sudden oak death Phytophthora ramorum
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Sudden oak death Phytophthora ramorum
Sudden oak death Phytophthora ramorum
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Sudden oak death Phytophthora ramorum
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Black pod disease of cacao
P. palmivora
P. capsici
P. megakarya
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Downy Mildew - Grape Plasmopora viticola Obligate
biotrophic pathogen Photosynthetic area
lost Fruit yield reduced Fruit rot
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Downy Mildew Symptoms and Signs
Signs
Early symptoms
Late symptoms
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.
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Downy Mildew Symptoms and Signs
Diseased fruit are off-color, shrivel and become
covered with white, downy fungal growth.
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Downy Mildew of Grape
Downy Mildew Plasmopara viticola
Sporangia

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

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Dew and rain contributes to duration of leaf
wetness
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Germination of Zoospores Penetration of germ
tube Highly dependent on duration of free water
on leaf surface
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• http//vegetablemdonline.ppath.cornell.edu/NewsArt
  icles/Cuc_Downy.htm

http//vegetablemdonline.ppath.cornell.edu/factshe
ets/Onions_Downy.htmClick
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Albugo candida