|Two-spotted spider mites
|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.|
|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.|
|Black spots on flowers.||See fact sheet|
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.|
|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.|