Petri plates are shallow, circular, glass or disposable plastic dish used to grow bacteria on solid media such as agar. A Petri plate test is described which can be used to screen for pathogenesis of fungi from diseased seedlings, plant roots, seeds or soil. Seedlings grown axenically on water agar are inoculated with test fungi and infection observed directly. The test method is also valuable for fungal identification as the formation of fruiting structures not normally produced on conventional media is often promoted. Sealed plates can be used for long-term storage of fungal cultures.