Plant Diseases

Many organisms, including viruses, fungi, and bacteria, can cause diseases in plants. Diseases can be specific to certain plants, but identifying them can still be extremely difficult.

Often, home gardeners mistake environmental or maintenance problems for diseases. For example, Spanish moss, lichens, and ball moss are not parasites that should be killed or removed; they are merely harmless plants themselves. Irrigating plants with salty well water can cause yellowing around the edges of leaves and leaf-drop starting from the bottom part of the plant’s canopy.

When a plant does have a disease, the problem may be merely cosmetic rather than truly damaging to the plant, like minor leaf spots. There are serious diseases, however, that can damage or kill plants they affect. Examples are mushroom root rot on landscape plants, lethal bronzing disease in palms, and take-all root rot on turf. Such diseases can seriously damage the plant’s appearance or growth.

Do not assume a disease is in the works just because of a plant’s appearance. Use a magnifying glass to look for insect pests that may be causing the damage. Consider maintenance practices. If you still suspect a disease, contact your county Extension office for advice on how to collect and submit plant samples for disease diagnosis and recommendations on the least toxic methods of treatment.