Forest pathology is a subfield of forestry and plant pathology that researches biotic and abiotic maladies affecting the health of a forest ecosystem. This primarily deals with fungal pathogens and their insect vectors. Forest pathology is part of the broader approach towards forest protection.

Forest pathology has its origins in Europe with Robert Hartig who is considered the father of the discipline. Hartig wrote the first textbook in 1874 which was translated into English by Harry Marshall Ward in 1894. Hartig and Ward along with William Somerville went on to publish Text-book of the Diseases of Trees in 1894.

Forest pathology is the research of both biotic and abiotic maladies affecting the health of a forest ecosystem, primarily fungal pathogens and their insect vectors. It is a subfield of forestry and plant pathology.

As of 2015, insects, diseases and severe weather events damaged about 40 million hectares of forests, mainly in the temperate and borealdomains.

There are a number of abiotic factors which affect the health of a forest, such as moisture issues like drought, winter-drying, waterlogging resulting from over-abundance or lack of precipitation such as hail, snow, and rain.

Wind is also an important abiotic factor as windthrow (the uprooting or breaking of trees due to high winds) causes an obvious and direct loss of stability to a forest or its trees.

Often, abiotic factors and biotic factors will affect a forest at the same time. For example, if wind speed is 80 km per hour then many trees which have root rot (caused by a pathogen) are likely to be thrown. Higher wind speeds are necessary to damage healthier trees.

Fire, whether caused by humans or lightning, and related abiotic factors also affect the health of forest.