Abiotic disease: A disease caused by a nonliving agent, i.e. water, heat, damage

Anthracnose: A necrotic sunken lesion on leaf or fruit caused by fungi.

Biotic disease: A disease caused by a living organism, i.e. bacteria, fungi

Blight: General and rapid browning of leaves, branches, and floral organs, resulting in rapid death of the host.

Black spot: Fungal disease on roses.

Brown spot: Fungal disease general found in turf or on leaves.

Canker: A dry, discolored, sunken, or cracked area on a stem, branch, or trunk. Caused by pathogens or injuries. Generally have distinct border between diseased area and healthy tissue.

Chlorosis: Yellowing of green leaves. Can be result of virus, lack of oxygen in waterlogged soil, pH imbalance or virus.

Damping off: Happens in young seedlings. A rapid death caused by fungi.

Decline: Downward declining condition of plants. Symptoms are small, brittle, yellowish or red leaves. Some defoliation may be present.

Dieback: Extensive death of twigs beginning at the tips and moving down to base.

Dry rot: The roots and fruits disintegrate because of fungi without the evidence of fluids. Soft rot is soft, oozing and the result of bacterial infection.

Gall: A swelling on the plant twig, trunk or roots.

Host: A plant of any type. A pathological organism.

Leaf spot: Lesions of dead and dying cells on leaves.

Mildew: Fungal disease with spores on leaves. Powdery mildew feels like powder. Downy mildew feels like felt.

Mosaic: A symptom on leaves with the appearance of intermingled patches of normal and light green or yellowish patterns. This is usually a viral disease.

Necrosis: Death of plant parts. Areas turn black or brown.

Parasite: An organism living on a host. The obligate parasite requires a living host and obtains foot from the host. The non-obligate parasite can live on a host or non-living object.

Pathogen: This is an organism or agent, i.e. fungus, bacteria, virus or nematode. It is capable of causing disease in the host, migrating and infecting other hosts.

Pathogenesis: Process in disease development. The time from infection to host reaction.

Ringspot: Circular area of chlorosis or necrosis with a green center. It is viral.

Root rot: The decaying of roots, usually caused by fungi.

Rosette: Short bunchy habit of plant growth.

Scab: Localized lesions on fruit, leaves, etc. Often raised and cracked with a scabby appearance.

Scorch: Burning of leaf surface at margins or entire surface

Shot holes: Small holes in leaves that are a result of disease where tissue dropped out (fungal) or from hail.

Soft rot: Slimy softened decay of fruits, bulbs, and leaves. It is a bacteria infection.

Stunting: Reduced plant growth

Symptom: The appearance of disease or injury.

Take-all-patch: Fungal disease in turf.

Wilt: Loss of rigidity.