The Plant Diagnostic Laboratory provides plant problem diagnosis for all crops. Most diagnoses are based on microscopic examination of the specimen and visual identification or culture of plant pathogens such as fungi, bacteria and nematodes. Identifications of plants, insects and mites attacking plants are also performed. Some specimens are referred to specialists in other departments or other institutions for diagnosis.
Since 2002, the lab has also been an active participant in the National Plant Diagnostic Network, which links together land-grant university plant diagnostic laboratories for the purpose of rapid detection of exotic and invasive plant pest species which pose a threat to US agriculture. Laboratory staff also conduct educational programs on plant pathology topics for various audiences, and prepare fact sheets and other materials related to plant disease management.