CLADOSPORIUM CITRI MASS. AND

C. ELEGANS PENZ. CONFUSED

H. S. FAWCETT

A series of errors that need to be corrected appears to have crept into plant disease literature, as to the name of the fungus causing "scab" or "verrucosis" of Citrus. The first account of this disease was published by F. Lamson-Scribner in October, 1886.* A fuller account with a colored plate appeared in the annual report of the U. S. Commissioner of Agriculture for 1886 (pp. 120-121). Scribner referred to the fungus as Cladosporium sp. A detailed account of the disease and the fungus was later published by W. T. Swingle and H. J. Webber,† who also referred to the fungus as Cladosporium sp.

In Tubeuf and Smith's "Diseases of Plants," published in 1897, reference is made on p. 509 to the above authors under the name of Cladosporium elegans Penz. This is the beginning of the errors. That the citrus scab referred to by Scribner is not Cladosporium elegans is evident from Penzig's description and figures in "Studi Botanici Sugli Agrumi," published in 1887. The dimensions of the spores of C. elegans are too large and the pathological effects on the leaf as figured by Penzig are not at all the same as those described by Scribner. The spores of the former are given as 18-20 X 5-6p, while the latter are 8-9 X 2.5-4μ.

Massee, in his "Text-book of Plant Diseases," published in 1899, described both fungi. On p. 310, he describes the scab under the name of Cladosporium Citri "protem," and says: "This Cladosporium species is evidently quite distinct from Cladosporium elegans Penz. which forms arid, brown spots on living leaves of oranges in Italy." An error in print, however, occurs on p. 436 of the same book, where a technical description of the fungus is given under the heading 'Cladosporium Citri

* Bull. Torrey Club 13: 181-183. 1886.

Bull. Div. Veg. Phys. & Path. 8: 20-24. 1896.

Penzig." This error is responsible for the writer's error in the annual report of the Florida Experiment Station for 1907, p. xxiii, where the fungus is mentioned as Cladosporium Citri Penz., instead of Cladosporium Citri Mass. Presumably as a result of Tubeuf and Smith's mistake, this fungus has been erroneously referred to as Cladosporium elegans Penz. in the following publications:

"Citrus Fruits and Their Culture," by H. H. Hume, published in 1904.

"First Annual Report of the Cuban Experiment Station, for 1904, 1905," by F. S. Earle.

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Bulletin 9 of the Cuban Experiment Station," by M. T. Cook and W. T. Horne, 1909.

Specimens of this fungus have been issued recently in "Fungi Columbiani" by E. Bartholomew under the name of Cladosporium Citri Mass., which is undoubtedly the name by which it should be designated.

AGRIC. EXP. STATION,

GAINESVILLE, FLA.

A NEW HOST AND STATION FOR

EXOASCUS FILICINUS

(ROSTR.) SACC.

W. C. COKER

On May 14 of this year, I noticed a number of plants of the Christmas fern (Dryopteris acrostichoides) whose fronds were attacked by a fungus, causing well-defined yellowish areas up to a centimeter or more wide on both the sterile and fertile leaflets. The ferns were growing in a deep ravine along the Raleigh Road, Rocky Ridge Farm, Chapel Hill, N. C. Specimens were brought to the N. Y. Botanical Garden, where Mr. F. J. Seaver determined the fungus as Exoascus filicinus (Rostr.) Sacc. (Taphrina filicina Rostr.), and careful dissections and measurements made by me showed our parasite to agree in every way with descriptions of that species. The asci do not break through nor push off the epidermis, but form a dense layer on its surface. They are small, averaging about 33 μ long and 5 or 6 μ wide, and the spores are about 5 μ long and 2 μ thick.

This Eroascus seems to have been observed heretofore only in Sweden, on Dryopteris spinulosa (Polystichum spinulosum). It will probably be found in other places in America and on still other species of Dryopteris.

CHAPEL HILL, N. C.