Fungi, Mold, Bacteria and Virus Pests

Diseases that affect indoor plants are generally bacteria, fungus and mold related.  Most fungal and mold problems can be prevented or controlled by using good watering practices.

Allow infected plants to dry down so the roots can recover.  Watch for the plant to begin growing new leaves.  This is an indication of improvement.  If the plant looks really bad, replace it.

Note: Always clean any tool that comes in contact with the soil or plant material infected by any disease. Wash your hands frequently. These infections can easily spread.

Here is a list of the many common diseases you may encounter.  Additional information about diseases that affect specific plants can be found in “Plant Care Guide”

• Anthracnose is an airborne fungus and can spread easily to neighboring plants.  The main symptoms are dark, ragged, circular, often sunken wet spots on leaves, stems, and fruits. Different species infect different plants.  It most often occurs in high humidity or where overwatering is present. If keeping the plant’s soil dryer does not resolve the problem, consider replacing the plant and destroying the diseased plant material.
• Blight is a fungal disease that attacks and causes sudden leaf damage. The main symptoms are blackish brown spots on leaves that start out in a mostly circular shape with yellow halos and occur first on the lowest, oldest leaves. In severe infections, stems become infected and black fungal spores are seen. It most often occurs in high humidity or where overwatering is present.  If keeping the plant’s soil dryer does not resolve the problem, consider replacing the plant and destroying the diseased plant material.
• Canker is a disease in which an area of dead tissue is covered by layers of callus tissue which the plant produces to seal off the diseased area.  The canker tissue will expand until it eventually encircles the branch, at which time the branch will die.
• Edema is a leaf spot disease caused by excess humidity or severe temperature fluctuations.  The roots absorb more water than the leaves can shed which causes plant tissues to expand and blister on the undersides of the leaf.  When the tissues dry, the blisters open up and turn a rusty color. Keep the plant dryer and try to provide more light to the plant.
• Powdery mildew is a plant disease caused by any of several species of fungi.  The mildew appears as a white powdery coating on leaves and stems.  Keep the plant debris cleaned up and keep the plant’s soil dryer.  Clean the leaves with a clean cloth; do not use the cloth on another plant until it has been sanitized.
• Root rot is a generic name for any of the root diseases caused by soil-inhabiting diseases such as Phytophthora.  If keeping the plant’s soil dryer does not resolve the problem, consider replacing the plant and destroying the  diseased plant material.
• Rust is a plant disease caused by Uredinales fungi.  It appears as streaks of reddish-yellow dust or pustules on the leaves or stems.
• Sooty mold is a dark gray or black unsightly mold that grows on honeydew.  It is most obvious on stems and bark as black dust that rubs off when touched.  It clogs the stomata, thereby interfering with photosynthesis.  Investigate to discover the pest causing the honeydew.  Control this pest to remove additional honeydew.  Clean stems and branches using a soft moist cloth to remove the mold.  Do not use the cloth on another plant until it has been sanitized.