Diplocarpon rosae

Diplocarpon rosae is a fungus that causes the rose disease Black Spot. Because it was observed by people of various countries around the same time (around 1830), the nomenclature for the fungus varied with about 25 different names. The asexual stage is now known to be Marssonina rosae while the sexual and most common stage is known as Diplocarpon rosae.

Diplocarpon rosae over seasons as mycelia, ascospores, and conidia in infected leaves and canes. In the spring during moist, humid conditions, ascospores and conidia are wind-borne and rain splashed to newly emerging leaf tissue. Upon infection, disease progresses from the lowest leaves upward causing defoliation and black spots on leaves.