Posted by: marinvit | April, 2010

Orchid Diseases

Orchids are subject to a number of pests & diseases.

-introduced with newly acquired or non-orchid companion plant

-poor or erratic growing conditions within the greenhouse

-weak & unhealthy plants as a result of poor horticulture

pests – an infestation i.e. the plant is attacked from without

diseases – an infection where the plant is attacked from within

ailment – a deficiency or excess of nutrients & environmental factors


generally insects or molluscs

pests – mites

– spider mites, false spider mites

– thrips

– aphids

– mealy bugs

– scale insects

– other insects – cockroaches, weevils, flies, millipedes etc.

– ants

– slugs

– snails

– others

Identification of pest and damage
Two spotted mite  – pale yellow/green, 2 dark spots on sides, 4 pairs legs, rounded

Damage – feed on undersides of leaves, speckled appearance, eventually turning black covered with silvery /bronze webbing, curling under of leaves

False / red spider mite – white/yellow becoming red with age, 3 pairs of legs, rounded

Damage – feed on undersides of leaves, fine pitting turning to a white/yellow flecking (dead cells) general discoloration & leaf drop

Thrips – yellow brown, elongate slender, moves rapidly

Damage – deposit eggs in cells- watery bruise (magnified) of stems & leaves, feed damage – glaucous or rusty spots on leaves, turning black finely spotted transparent or blackish discoloration flowers, distorted buds

Aphids – greenfly, green or black easily visible

Damage – distorted buds, new growths, stems, spikes

Mealy bugs – soft bodied covered in white powdery wax and filaments

Damage – hidden under dry bracts, sheaths & between roots, leaf & stem axils. Suck plant sap, turns yellow

Soft or armoured scale – flattened, rounded yellowish to black, only nymphs mobile

Damage – found on leaf surface, axils, hidden under bracts & sheaths, on rhizomes. yellowing of tissue, leaf drop, some blackening

Boisduval scale    – males in cottony white masses, females whitish circular shields

Damage – in leaf axils, hidden under sheaths and bracts. Yellowing of tissue, some blackening, leaf drop


  1. ya……….
    Thanks for providing a great information regarding to orchid diseases. Its very helpful to grow orchid plants in the garden. ………

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