Moth Orchid: Pests and Diseases

Phalenopsis Orchid   
Multiforal phalaenopsis


* Only use pesticides with low toxicity, especially in the house. Most of these will have a 'caution' on the label. Products labelled with 'warning' or 'danger' should be avoided. Always use the least toxic methods to deal with pests and diseases first.

 


 

Insect Pests      
Most insect pests can be gently washed off, or swabbed with isopropyl alcohol. Mealy bugs and scale are especially fond of phalaenopsis and like to hide in the leaf axis so examine these carefully.   Use Safer insecticidal soap or SunSpray ultra fine Spray oil after reading all directions carefully, if mealy bug infections persist. Do not use regular garden oil! Hard scale is best washed off with warm soapy water or scraped off the leaves with an old toothbrush and then sprayed as described above.

Bacterial and Fungal Infections
Moth orchids ain cultivation seem to be more susceptible to bacterial than fungal infections which can result in brown spots or rotted areas on leaves, which can quickly lead to the demise of plants. 

Bacterial soft rots, such as pseudomonas, often infect plants at high temperatures and when there is plenty of water. These rots are characterized by soft fluid-filled areas on the leaves that can spread very rapidly. Infected areas often have a bad odor.

Carefully cut out infected tissue at the earliest sign of infection with a sterile blade.  Sprinkling the affected areas liberally with cinnamon will also help as it has anti-fungal microbial properties. You can also spray plants with a fungicide/bactericide such as Physan but handle with care, and try the cinnamon first. Isolate the plant, avoid wetting the leaves, and increase air circulation.


Good culture will eliminate most bacterial and fungal infections. Among the two most important things you can do are:

i) maintain good air circulation whenever humidity is high, irrespective of temperature and
ii) make sure foliage is dry by nightfall by watering plants early in the day.