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LEAF-SPOT: Cercospora dendrobii, C. epipactis, C. peristeriae Plus Six Other Cercospora Sp.

Ailments Orchid Doctor

by Robert M. Hamilton (Compiler)

Originally published in The Orchid Doctor in 1980 and 1988

Posted by Sys Admin over 1 year ago.

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Usually shows as yellowish or brown spots on underside of leaves; sometimes join together to form larger spots; all are controlled by spraying with Benlate at 1 ttpg. with a wetting agent, and repeat at 15 day intervals three times to eliminate it from the greenhouse; illus. AH23+

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Leaf-spot Comments
LEAF-SPOT: Cercospora angraeci Fungus found in Florida in 1964; tiny tan or light brown spots become dark purple-brown; may occur in a circular pattern or on a whole leaf; spray with benomyl 50WP at 1 ttpg. fortnightly three times and use a wetting agent; or, with Daconyl 2787; destroy leaves; space plants out. BU24 This has been reported on various angraecums, dendrobiums and odontoglossums. AH86-77 0
LEAF-SPOT: Cercospora dendrobii Infects dendrobiums as light yellow area under leaves; circular enlargement; spots become sunken, purple-black, yellow margined; corresponding yellow-green areas follow on top; spreads to other plants; spray with benomyl 50WP at 1 ttpg. fortnightly, or with Ferbam, or Zineb. B21; BU20 0
LEAF-SPOT: Cercospora dendrobii and Others Control is a spray with benomyl or Benlate 20 at 1 ttpg. AH86-76 0
LEAF-SPOT: Cercospora epipactidis On Phaius grandifolius, etc.; tiny sunken, yellow spots under leaves, later on top also; enlarge in a few days and become sunken, purple-black; about 1/2 inch or larger; on old lesions center falls out; spray with benomyl at 1 ttpg., or with Ferbam or Zineb. B18; BU19 0
LEAF-SPOT: Cercospora odontoglossi Control by spraying with benomyl (Benlate 50W) at 1 ttpg plus wetting agent, three times at 15 day intervals. AH86-80 0
LEAF-SPOT: Diplodia Laeliocatleyae Small yellow areas on top and bottom of leaf turn brown, become black and greasy; spray with fungicide such as Fore/ Dithane; Benlate is not effective in this case. AH86-70 0
LEAF-SPOT NECROSIS: Control by Various Compost Techniques A build-up of undissolved solutes in water cause the leaves to die at the tip; it also causes punctate areas of necrosis of tender leaves of species such as stanhopeas, pescatoreas, lyxastes, etc.; good drainage and much leaching helps; the "wet growing" system is described, emphasizing use of Palco wool and plastic chips medium; refer to OD68-8 0
LEAF-SPOT: Phyllosticta pyriformis It is infrequent in Florida; it blemishes the leaves; starts as tiny slightly yellow spots, sunken, which enlarge and turn tan to dark brown or red with black margins; control with benomyl (Benlate 50W) A86-814 0
LEAF-SPOT: Septoria selenophomoides Usually found on imported plants; starts as tiny yellow lesions, enlarges and turns dark, the spots coalesce; leaves soon fall and promote more infective spores; spray with benomyl (Benlate 50W) at 1 ttpg. three times fortnightly. AH86-69 0
LEAF-SPOT: Soft Spots Slowly Cover the Whole Leaf The condition should be treated early with Truban, 1 to 1.5 tpg. thoroughly even to the point of drenching, after removing the blackening leaves; if Truban is unavailable use Lesan (Dexon). A81-688 0
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