Growing problems

Insect pests

Two-spotted spider mites (Tetranychus urticae)

Symptoms: Discoloured foliage, fine web appears. Mostly affects Cymbidium.

Treatment: See fact sheet.

False spider mites or flat mites (Brevipalpus russulus)

Symptoms: Pits on upper leaf surface.

Treatment: Same treatment as for two-spotted spider mites. See fact sheet.

Aphids (Cerataphis lataniae)

Symptoms: Spotted or deformed flowers or none at all. Aphids like young shoots and flower spikes.

Treatment: See fact sheet.

Mealybugs, scale insects (Pseudococcus longispinus, Diaspis boisdevalii)

Symptoms: Powdery white mass in leaf axils; small brownish shells all over the plant.

Treatment: See fact sheet.

Diseases

Botrytis blight (Botrytis cinerea)

Symptoms: Black spots on flowers.

Treatment: See fact sheet.

Leaf spot (Cercospora sp. / Gloeosporium sp.)

Symptoms: Round brown or black spots on the upper or under surface of leaves, sometimes on tips.

Treatment: Improve air circulation. Wipe off any water remaining on leaves after watering. If possible, remove the worst-affected leaves.

Heart rot

Symptoms: Centre of plant turns black and rotten. Leaves pull off easily.

Treatment: Destroy plant. Disinfect all tools.

Bacterial diseases

Symptoms: Slightly damp brown spots on leaf surface. Affect mostly phalaenopsis and paphiopedilums.

Treatment: Remove infected parts. Disinfect all tools.

Viral diseases

Symptoms: Mosaic or necrotic rings on leaves, stunted growth and deterioration of the plant, mottled or streaked flowers.

Treatment: No effective treatment. Destroy plant. Disinfect all tools.

Physiological problems

Insufficient light

Symptoms: Dark green leaves. Poor or no flowers. New shoots smaller.

Solution: Increase light intensity.

Too much light

Symptoms: Yellowed leaves. Whitish burns on upper surface of leaves. Slow growth.

Solution: Decrease light intensity.

Insufficient water

Symptoms: Wilted leaves and pseudobulbs. Deformed leaves.

Solution: Increase frequency of waterings.

Too much water

Symptoms: Wilted leaves and pseudobulbs. Leaves turn yellow and drop off. Roots deteriorate.

Solutions: Decrease frequency of waterings, repot and remove affected parts.

Lack of humidity

Symptoms: Wilted leaves. Shrivelled leaves.

Solution: Mist leaves. Use a humidifier or place the plant on a bed of gravel in a water-filled saucer.

Too much humidity

Symptoms: Leaf spots and black spots on pseudobulbs.

Solutions: Improve air circulation. Remove affected parts.

Sudden drop in temperature

Symptoms: Leaf spots, tips of leaves brown.

Solution: Protect from drafts.

Mineral deficiency

Symptoms: Yellowed leaves. Slow growth.

Solution: Fertilize properly.