Plant pathology is the study of what causes plant diseases, why they occur, and how to control them. Plant pathology is composed of many other disciplines such as botany, microbiology, nematology, virology, bacteriology, mycology, meteorology, biochemistry, genetics, soil science, horticulture, agronomy, and forestry.

Plant pathologists are usually interested in populations of diseased plants and not in individual diseased plants. Plant diseases have had a major impact on mankind. Diseases such as coffee rust have changed the way people behave and/or their customs. Diseases such as ergotism and late blight of potato have led to the deaths of thousands of people. Diseases such as southern corn leaf spot, chestnut blight, and dogwood anthracnose have appeared suddenly and caused millions of dollars to be lost in damage as the pathogens of the diseases spread through the ranges of the hosts.

Among the various disciplines of agriculture, plant pathology is an important stream, as it pertains to diseases; its diagnosis, management, forecasting, forewarning, quarantine and genetic engineering, all of which can help enhance yield. This is beneficial not only to farmers, but also to the society at a great extent.