NYBG.org: Taphrina collections of A. J. Mix

Arthur Jackson Mix (1888-1958) was on the faculty of the University of Kansas most of his professional career, beginning in 1916. Even today, he is considered the world authority on Taphrina, the "peach leaf curl" fungus, and his monograph is the standard reference for this group (University of Kansas Science Bulletin, vol. 33, Pt. 1, No. 1, 1949). It is suspected that Mix's graduate student, Charles Kramer, eventually acquired his herbarium and took it with him to Kansas State University (KSU) where he served as a faculty member. Although a substantial number of Mix's Taphrina collections from KSU were transferred to NYBG, it is yet to be determined if his herbarium was transferred as a whole to KSU, or if some of his specimens remain at University of Kansas.

The genus Taphrina, founded by Fries in 1832 on the species Taphrina populina, is the only recognized genus in the family Taphrinaceae, order Taphrinales of the Ascomycetes. It is a widespread genus, and at present contains approximately 95 species, all of which are parasitic on vascular plants. This fungus has four unique or unusual features. (A) The assimilative mycelium is dikaryotic which immediately distinguishes it from most other ascomycetes and therefore raises the question about the placement of this order. (B) It produces an exposed layer of asci on the surface of the host leaf. Since there is no surrounding or supporting fungal tissue, there is nothing that can be called an ascoma. (C) The ascospores often bud in a rather yeast-like manner while still inside the ascus. (D) When the asci dehisce, they tend to split across the tip, rather than around it, so they are distinctly atypical of the operculate group. Evidently, this group sits uneasily among the other ascomycetes.

The genus Taphrina is most often associated with peach leaf curl disease, which causes leaves to become thickened and distorted. Peach leaf curl disease is caused by Taphrina deformans and is one of the most common and widespread diseases affecting peach plantings in the United States. As the name implies, the most common and striking symptom of leaf curl occurs on the foliage. The fungus causes the meristematic cells at leaf margins to proliferate quickly and randomly, which results in the leaves becoming variously wrinkled, puckered and curled.

In 1952-53, several years before his death, A. J. Mix reviewed the entire collection of Taphrina species at NYBG, and most of the specimens in the NYBG herbarium have been annotated by him. They have been completely rearranged according to his 1949 Monograph. His collection of Taphrina species recently received by NY from KSC is presently being incorporated into the NYBG Herbarium.

The following web pages contain additional information on peach leaf curl and other diseases caused by Taphrina species:

The Taphrina Collection of A. J. Mix