A plant disease is any disturbance that usually interferes with function, economic value, normal growth, development and aesthetic quality of a plant. A plant disease can be caused by two general groups of casual agents which are pathogens and antipathogens.
The different types of diseases usually occurring in plants are:
Blights − When plants are suffering from blight or branches and leaves suddenly start withering, they stop to grow and then they die. After this process is continued for some time the parts of the plant start to rot.
Cankers − Cankers are usually formed on woody stems where the stems may crack. They start to ooze continuously for a period of time and can girdle trunks or shoots, which causes everything which is present above to wilt and die. The cold injury symptoms lead to the development of cankers.
Rots − Rots are diseases which decay roots, flowers, fruits, stems, and wood. Sometimes the diseases cause the leaves to rot for a period of time, but those symptoms tend to be described as leaf spots present. These rots are caused by various fungi and bacteria.
Other types of diseases are also present:
Rusts − Rusts can be categorized into a special type of fungal disease. These types of rusts are obligate parasites and live on usually healthy and vigorously growing plants. The infection is mostly limited to perennial plant parts such as leaves, petioles, tender shoots, stem, and fruits. They complete their life cycle, on the host plant. These typical rust systems include a tan to rust which is color coated. Some of them forms obvious rusts and the plant species face severe problems. These rusts can damage small plants and can also kill huge trees. Once these rusts start it's very difficult to stop them.
Wilts − Wilts are plants which wilt when they don't get enough water. These fungi and bacteria attack or clog a plant's water conducting system and they cause permanent wilting which is very severe to the plant. This is often followed by death and these wilt symptoms resemble those of blights.
Anthracnose − Anthracnose is a birds eye spot which is a fungal disease. It usually forms small dead spots which have a raised border and a sunken center that have colors of pink and brown. The symptoms are very obvious on the pods which are present either in a circular, black or sunken spots which may ooze pink slime which develops into pink borders as they age which has no control over the plant growth causing the plant to die at some point when it tends to undergo stress.
Club root − Club root is the plant disease which affects the vegetables and flowers in a cabbage family. During the heat of the day, these are affected by fungus and start to wilt. These roots are swollen and distorted in every manner possible, without any proper structure.