Diseases

A disease is an abnormal condition in a plant which impairs the plant's appearance, function, or value. Diseases are caused by microorganisms and by environmental factors. Diseases are divided into two groups, pathogenic diseases which are caused by other organisms and physiogenic diseases which are caused by environmental factors.

The three requirements for the development of disease include a susceptable host, a primary causal agent, and a favorable environment. This is also known as the disease triange.

Symptoms may be necrotic or non-necrotic. Necrosis means death. Necrotic symptoms include the death of a part of a plant or the entire plant.

Plant diseases include nematodes, fungi, bacteria, viruses, mycoplasmic organisms, and physiopaths. Physiopaths are non-pathogenic agents that may cause disease or the spread of disease.