Bacterial Brown Spot
The symptoms may appear anywhere on the leaf as
a small, soft, water soaked blister. Initially dirty green in color, the
infected spot enlarges, coalesces and eventually becomes brown or black, dried
up and sunken. It oozes bacteria-laden liquid, particularly when the disease
reaches the tip of the leaf. It is most prevalent during the warmer weather.
In Cattleya, the infection enters through
wounds on older plants and usually affects only older leaves.
It advances slowly and is rarely fatal.
In Phalaenopsis, the blister-like spots may be
surrounded with a yellowish or pale green halo.
Spots coalesce, and the infection spreads
If the diseased area invades the crown, the
plant will die.
Immediately remove infected tissue and spray
the plant with
a bactericide like Physan or copper compounds
following label instructions.
Disinfect growing area with 10% bleach
Pseudomonas cattleyais a water-borne pathogen
that prefers warm, moist conditions. Reduce humidity and temperature (if
possible), eliminate overhead watering and increase air circulation.