How to Treat Orchid Bacterial, Fungal Diseases

Bacterial and fungal diseases can strike even hardy orchid species like Just Add Ice Orchids. When Phalaenopsis orchids are infected by orchid fungal diseases or orchid bacterial diseases, beginning corrective treatment promptly will improve your orchid’s chance of recovery.

As we noted in our previous post, discolored leaves and an unpleasant odor are the two most obvious signs of a bacterial infection. Bacterial orchid diseases are caused by high temperatures and high humidity and usually have an obvious visual presentation. If daily inspection of your Just Add Ice Orchid reveals brown or soft spots; a bacterial disease is the likely culprit.

The most common orchid diseases are:

• Bacterial Brown Spot begins as a soft, watery lesion, usually on the orchid’s leaf, that eventually turns brown. In advanced stages, the brown spot will begin to exude a foul-smelling dark liquid.
• Bacterial Soft Spot (also called Erwinia) begins as a nasty-smelling wet spot on the orchid’s leaf. The infected area will expand rapidly and within 1 to 2 days the entire leaf will become soft and slimy.
• Fungal Crown Rot is the most common and dangerous orchid fungal disease. At its beginning, orchid owners may notice a subtle discoloration at the center of the plant or at the base of the leaves. Crown rot is caused by a combination of overwatering, poor air circulation and low temperatures. If untreated, plants can die within a week.

To control orchid diseases:

Immediately remove infected foliage using a sterilized razor. Relocate your orchid to expose it to better air circulation, lower humidity and temperatures between 65 and 80 degrees. Spray your orchid with a good quality, broad-spectrum fungicide, following package directions. Even if you suspect a bacterial disease, fungicide application will prevent secondary infection.

Photo by: Scot Nelson