BLACK ROT: Leaves on Cattleyas Develop Black Spot At Top, Eventually Killing Leaf and Sheath

Ailments Orchid Doctor

by Robert M. Hamilton (Compiler)

Originally published in The Orchid Doctor in 1980 and 1988

Posted by Sys Admin over 3 years ago.

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Use Dexon-35 or Truban, 1 tpg. as an overall drench, or soak for 20 to 30 minutes; repeat in 14 days. A72-905; A79-1112
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Black Rot Comments
BLACK ROT: Caused by Fungi Pythium ultimum and Phytophora cactorum Most destructive to cattleya-types; worst during cool months; purplish brown area on leaf or root and rhizome and upward into pseudobulbs; drench with Truban 1/2 tpg. AH16 0
BLACK ROT: Fungicide as Preventive Dexon-35 can be so used; also, Truban; packages are commercial size, try to obtain from a commercial grower. A74-896 0
BLACK ROT: In New Leads of Potinara; Benlate and Natriphene Did Not Control Use 1/2 tpg. drench of either Dexon-35, Truban, Terrazole or Banrot; commercial greenhouses may sell a few spoonfuls of one of them. A75-500 0
BLACK ROT: Leads Go Black, Leaves Change to Lighter Color and Wrinkle; Pseudobulbs Wrinkle and Show Brown Patches Truban is effective; cut off all diseased parts; plunge all into solution 1 tpg. A74-1062 0
BLACK ROT: On Cattleyas Control with Truban or Dexon-35; Truban is gaining favor over Dexon-35; drench or soak in 1 tpg. A72-341; A75-680; A79-1112; use Tersan or Fermate. S198 0
BLACK ROT: On One-inch New Growths This indicates a root disease; dip in Banrot solution ltpg., before repotting; another fungicide to try is Subdue, which may be effective. A81-393; RMH 0
BLACK ROT: On Specimen Cattleya; Benlate Does Not Cure Black rot is not cured by Benlate, use Dexon-35, 1 tpg. soak for 20 minutes. A74-217 0
BLACK ROT: Phytophora Cactorum Leaf and heart rot; cattleyas are the main host; fungus attacks all parts except roots; shows purple, purplish brown or black; leaves often become brittle and can be jarred off; caused by coolness and high humidity; cure must include introducing agent inside plant tissue; use Natriphene dip for 60 minutes, or Dexon 70%, or Thiram 75% (Tersan) WP, at rates given for 100 gallons; repeat in one month; Physan and Shield are good for seedlings; avoid overhead watering. B7; BU8+ 0
BLACK ROT: Pythium Sp. of Fungi On cattleyas; cut rot away ruthlessly; burn the compost; immerse plant in Orthocide captan at 1 teaspoon to 1 pint water for one hour. OR76-99 0
BLACK ROT: Pythium Ultimum Most destructive of cattleyas, others are susceptible; similar symptoms to Phytophora cactorum; small water-soaked spots, later turn purplish black; yellow margin advances; spread quite rapid, 2 or 3 inches per day; often following dividing of plants; spread by splashing; dip for 60 minutes in Natriphene; use Tersan as preventive. B9; BU10; OR74-234 1
BLACK ROT: Tips of New Cattleyas Turn Brown Caused by a fungus; remove all infected growth; soak pot and plant in 1/2 tpg. Dexon-35 or Benlate. A72-686; F69-94 0
BLACK ROT: Treatment with Dexon Remove diseased parts; soak or drench pot in one teaspoon per two gallons water three or four times at 10 to 14 day intervals; it is surface effective only. A74-969 0
BLACK ROT: Two Kinds Are Prevalent One is a cool-weather rot, the other is a warm-weather type and both cause blackening of leaf tissue; both are contagious and can be spread by splashing water; keep plants dry, spray with Benlate; the summer type can destroy a plant in three days, in some areas. OR85-69; F81-17 0
BLACK ROT: Water Mold Pythium Ultimum Is the Cause The special enemy of commumity pots of seedlings; damp-off; spray with Physan, Anti-Damp, or Natriphene once a month as preventive; on mature plants cut out rot; soak plant in good fungicide, dry, treat with Tersan; illus. A66-399+; A73-811 0

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