ANTHRACNOSE: Leaf Spot

Orchid Doctor

by Robert M. [Bert] Hamilton (Compiler)

Originally published in The Orchid Doctor in 1980 and 1988

Posted by Sys Admin almost 4 years ago.

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Leaves develop circular or oval sunken spots, which are reddish changing to dark brown or grey; for controls use Captan or Benomyl at 1 ttpg. AU85(4)-31

Many genera are affected by Gloeosporium and Colletotrichum in warm temperatures with excessive moisture and poor light; leaves develop circular or oval sunken spots; reddish brown, change to dark brown or gray; fruiting bodies form; treat spots with copper Bordeaux mixture, Tersan, Zineb; refer to N317+; use Captan, Ferbam, Zineb. S202; use benomyl at 1 ttpg.

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Anthracnose Comments
ANTHRACNOSE, AMERICAN: Glomerella Cincta Most common on leaves; weakened plants are most susceptible; brown discoloration round in shape, possibly sunken; cut off parts, spray with benomyl, 1 ttpg; repeat in a week; or, spray with zineb, captan or ferbam; avoid sun-scald; avoid high nitrogen; to prevent on new flowers spray with 1:2,000 Natriphene + drop of detergent. B11, BU13 0
ANTHRACNOSE, AMERICAN: Glomerella Sp. + Colletotrichum Sp. The latter stages attack above-ground; brown discoloration, round or irregular, more or less sunken, rather sharply defined; spore pustules show in dead areas on leaf or flower. AH29 0
ANTHRACNOSE, EUROPEAN: Gloeosporium Affine A weak parasite; lesions on leaves and pseudobulbs slightly sunken, yellow to light green, circular; later, spore-bearing structures appear. A66-480; AH29Spots on leaves yellowish or light green, then light brown, dotted with spore-bearing structures of concentric rings; with humidy, rose-colored spores ooze out; cut off and burn; spray with benomyl at 1 ttpg.; repeat in a week; or with ferbam, captan or zineb; dip for five seconds in Natriphene 1:2,000; avoid overhead watering. B12,; BU14 0

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