Bacterial diseases
Pseudomonas cattleyae is the most important bacterial disease infecting Phalaenopsis. The
disease can be recognised from the characteristic brown patches on the leaves, which have an
oily heart or spot and are surrounded by a yellow rim. An infection with Pseudomonas begins as
a small dark pit in the leaf. The spread of the disease can be countered to some extent by
adjusting the amount of nitrogen, hygienic measures (the removal of diseased plants) and the
maintenance of a constant relative humidity. Good and healthy planting material will prevent
problems with bacterial diseases.