THE SPECIES OF CIBORINIA PATHOGENIC TO HERBACEOUS ANGIOSPERMS

BATRA, LEKH R., and RICHARD P. KORF. (Cornell U., Ithaca, N. Y.) The species of Ciborinia pathogenic to herbaceous angiosperms. Amer. Jour. Bot. 46 (6): 441-450. Illus. 1959.-On the basis of anatomical studies, 2 distinct species of Ciborinia, a generic segregate of Scierotinia, are shown to occur on Erythronium. The life history and phytopathology of one of these, C. erythronii, are reported. The species is shown to be homothallic, to develop its sclerotia in nearly all parts -of the plant, to overwinter also in the form of mycelium in bulbs, and to form spermatia in the field. Experiments on factors affecting formation of sclerotia and apothecia in the laboratory are reported. Prolonged washing of sclerotia formed in the laboratory proved to be an important factor for development of apothecia. A new species, C. trillii, pathogenic to Trillium is described, as is a new species, C. violae, pathogenic to Viola. The generic diagnosis of Ciborinia is emended on the basis of these studies. A new combination, C. hirtella, is also proposed. THE GENUS Ciborinia Whetzel (1945) was erected for certain foliicolous species formerly assigned to Sclerotinia Fuckel but which differ from typical Sclerotinia species in forming erumpent sclerotia which partially or wholly digest the suscept tissue, usually leaving remnants of resistant tissue embedded in the sclerotial medulla. Both woody and herbaceous suscepts are known for Ciborinia species. Only the species attacking Popiulus L. have been critically studied, by Groves and Bowerman (1955), and little information has appeared concerning the species pathogenic to herbaceous plants. The experiments reported here were carried out primarily by the senior author during the period 1956-1958. The 4 species of Ciborinia described below and the diseases caused by them are thus far known only from central and eastern North America. MATERIALS AND METHODS.-Histological observations were made under a light microscope from sections cut either free-hand or by microtome from fresh, dried or paraffin-embedded material. Freehand sections were stained with KOH-phloxineglycerine (White 1941) and embedded sections, after passage through the usual xylol/alcohol series were stained in safranin and Heidenhain's hematoxylin (Johansen 1940). Single-ascospore isolations were made from at least 1 collection from each locality where fresh apothecia were obtained, 1Received for publication January 19, 1959. 2Respectively, Instructor (currently Lecturer in Biology, Swarthmore College) and Associate Professor, Department of Plant Pathology, Cornell University. The authors wish to acknowledge with thanks the loan of specimens from Mr. S. J. Smith, New York State Museum, and from Dr. J. W. Groves and Dr. D. B. 0. Savile, Science Service, Ottawa. Assistance with the Latin diagnoses was given by Dr. W. J. Dress, Bailey Hortorium, Cornell University. Prof. R. T. Clausen, Cornell University, gave assistance in host identifications. Dr. W. C. Denison, Swarthmore College, was particularly helpful in obtaining materials and assisting with experiments in Pennsylvania, for which the authors wish to express their deep appreciation. One portion of the paper was generously read for comment by Dr. J. W. Groves. by attaching a mature apothecium with petroleum jelly to the lid of a 9-cm. Petri dish, and inverting the lid over solidified potato dextrose agar. Twentyfour hr. prior to using such plates, the agar was flooded with a thin layer of 30 p. p. m. streptomycin sulfate solution to reduce bacterial contamination and to stimulate ascospore germination. Wellisolated, germinating spores shot onto the agar surface were later transferred to agar slants. For inoculation experiments, ascospore suspensions in sterile distilled water were made from freshlycollected apothecia and atomized on plants. In field inoculation studies, a bell jar was placed over a portion of the wild colony prior to atomizing the plants, to serve as a check. After inoculation, greenhouse plants were held in a moist chamber for 2 days and wild colonies were covered with a transparent plastic tarpaulin for a few days. Two SPECIES ATTACKING ERYTHRONIUM (LILIACEAE) .-The members of the family Liliaceae which are attacked by Ciborinia are all early springflowering plants, characteristic of wooded areas, but often cultivated as ornamentals in rock gardens. None are of any great economic importance. Two species of Ciborinia have been described as attacking the Dog's-tooth Violet, Erythronium L. C. gracilis (Clements) Whetzel was described on the White Dog's-tooth Violet (E. albidum Nutt.), and C. erythronii (Whetzel) Whetzel was described from the Yellow Adder's-tongue (E. americanum Ker.). We have been unable to secure fresh material of C. gracilis but have made a detailed histological study of an isotype specimen, and find that the species is amply distinct from C. erythronii, with which it had been placed in doub-tful synonymy by Seaver (1951). The gross morphology of the apothecia, the asci and ascospores, and the anatomy of the sclerotia of the 2 species are remarkably similar (fig. 1, 3-6, 8-10) . The excipular structure of the apothecia is widely divergent, however (fig. 2, 7), with a layer of large, thin-walled cells on the outer surface in C. erythronii, lacking such a layer in C. gracilis. Whetzel (1926) pointed out that C. gra-