David Geiser, Ph.D., is a professor in the College’s Department of Plant Pathology and Environmental Microbiology and Director of the Fusarium Research Center at Penn State.

Research in Dr. Geiser's lab focuses on the molecular evolutionary genetics of fungi, mostly in the realm of molecular phylogenetics and systematics at the species level. His team applies these tools mostly to identify and better understand the fungal culprits in plant and animal diseases and toxicoses. Unfortunately, identifying fungi using traditional micromorphological tools is very difficult, and tends to lead to species concepts that are too broad. Dr. Geiser's team uses the tools of multilocus molecular phylogenetics to recognize and identify species, which provides a much more objective and reliable framework for understanding the biology of these fungi.

As Director of the Fusarium Research Center at Penn State, Dr. Geiser also curates the world's largest collection of cultures of Fusarium, one of the most important genera of toxigenic and pathogenic fungi. The collection is nearing 20,000 accessions and provides isolates to certified researchers, and also provides identification and other services. Most of the research in Dr. Geiser's lab naturally involves this important genus, but he is also involved in projects in a variety of other fungi.