It is generally the study of diseases happens to trees. It is generally classified into biotic, abiotec and decline diseases. The plant pathology will put high impact on the crop production of the country. So reducing the plant diseases and losses of forest is the biggest concern of forest pathologist. A plant disease is defined as a sustained disruption in physiological or structural functions of a plant due to an attack by a pathogen that results in death, damage to cells or tissues, reduced growth or vitality, or economic losses. A disease is an interaction between a pathogen and its host that can only occur under certain environmental conditions.