Orchids Damaged by Lawn Chemicals? Spider Mite Diagnosis

Dying Orchids Under Lights: Spider Mites Suspected

Dottie grows under lights near a window. Window was open when gardeners applied lawn chemical; wind may have blown it onto plants. Lost almost all Phalaenopsis. Symptoms: rust-like film on leaves, base turns black, leaves die.

Expert Response

Dottie, a photo would help. Initial thought: spider mites. They create a film where they attack, reproduce rapidly, suck sap from leaves, often starting on undersides. Hardy red spider mite may cause rust color. They thrive in dry conditions. If mites, need insecticide effective against red spider mite; repeated sprayings needed as eggs hatch. Systemic insecticide helps on new growth. Lawn chemical likely too dilute to cause damage. Once mites weaken plant, fungal spores may enter, causing black tissue. This is one possible scenario fitting observations.