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Growing problems

Cymbidium (Gorey 'Trinity' AM/RHS x Maufant 'Rozel' FCC/RHS)
Photo: Jardin botanique de Montréal (Gilles Murray)
Cymbidium (Gorey 'Trinity' AM/RHS x Maufant 'Rozel' FCC/RHS).

Insect pests

Type Symptoms Treatment
Two-spotted spider mites
Tetranychus urticae
Discoloured foliage, fine web appears. Mostly affects Cymbidium.

See fact sheet.

False spider mites or flat mites                        Brevipalpus russulus

Pits on upper leaf surface. Same treatment as for two-spotted spider mites. See fact sheet.
Cerataphis lataniae
Spotted or deformed flowers or none at all. Aphids like young shoots and flower spikes. See fact sheet.
Mealybugs, scale insects Pseudococcus longispinus, Diaspis boisdevalii Powdery white mass in leaf axils; small brownish shells all over the plant. See fact sheet.


Type Symptoms Treatment
Botrytis blight 
Botrytis cinerea
Black spots on flowers. See fact sheet
Leaf spot
Cercospora sp. / Gloeosporium sp.
Round brown or black spots on the upper or under surface of leaves, sometimes on tips. Improve air circulation. Wipe off any water remaining on leaves after watering. If possible, remove the worst-affected leaves.

Heart rot Centre of plant turns black and rotten. Leaves pull off easily. Destroy plant. Disinfect all tools.
Bacterial diseases Slightly damp brown spots on leaf surface. Affect mostly Phalaenopsis and Paphiopedilums. Remove infected parts. Disinfect all tools.
Viral diseases Mosaic or necrotic rings on leaves, stunted growth and deterioration of the plant, mottled or streaked flowers. No effective treatment. Destroy plant. Disinfect all tools.

Physiological problems

Type Symptoms Treatment
Insufficient light Dark green leaves. Poor or no flowers. New shoots smaller. Increase light intensity..
Too much light Yellowed leaves. Whitish burns on upper surface of leaves. Slow growth. Decrease light intensity.
Insufficient water Wilted leaves and pseudobulbs. Deformed leaves. Increase frequency of waterings
Too much water Wilted leaves and pseudobulbs. Leaves turn yellow and drop off. Roots deteriorate. Decrease frequency of waterings, repot and remove affected parts.
Lack of humidity Wilted leaves. Shrivelled leaves. Mist leaves. Use a humidifier or place the plant on a bed of gravel in a water-filled saucer.
Too much humidity Leaf spots and black spots on pseudobulbs. Improve air circulation. Remove affected parts.
Sudden drop in temperature Leaf spots, tips of leaves brown. Protect from drafts.
Mineral deficiency Yellowed leaves. Slow growth. Fertilize properly.

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