SECTION OF VEGETABLE PATHOLOGY. 341 
Sorauer: Pflanzenkrankheiten; Berlin, ri@, Tul.; Ann.Sc. Nat. IV Ser. Tom. 
1886; pp. 367, 368; Plate II; Spheerella V; p.112: Spheria fragarie. 
fragarie (Tul.), Sacc.; ibid, 2d ed., IT: 
p. 366; Plate 15. 
nize; li; 767; Spheria fragariecola, 
Seribner, F. L.: Report U.S. Department | _ Wall. 
Agriculture; 1885; p. 82. | Winter: Krankheiten der Kulturge- 
Trelease, William: Second Annual Report  wachse; Leipzig, 1878; Rab. Kryp: 
Wisconsin Agricultural Experiment — Flora; II; p.370. 
Station; 1885; pp. 47-58; 2 figures; The | Report Connecticut Agricultural Ex- 
Spot Disease of the Strawberry Leaves: perimental Station; 1878; 108-111. 
New York Weekly Tribune, June 13 | Strawberry Rust; New England Home- 
and October 31, 1883; Preliminary List stead; 1886; p. 287. 
Parasitic Fungi of Wisconsin; p. 13. The Strawberry Fungus; Gardener's 
Tulasne: Selecta Fungorum Carpologia; Monthly; XXVIII; p. 247. 
II; p.286; Plate 31; Stigmatea fraga- 
2.—APPLE SCAB. 
Fusicladium dendriticum. 
(Plate II.) 
(a) GENERAL OBSERVATIONS. 
The disease of the apple caused by the fungus parasite Fusicladium 
dendriticum, has long been known to growers of this fruit as ‘‘Apple 
Scab.” Less frequently we hear it spoken of as “black spot,” er 
simply spot disease of the apple, or, when on the foliage, ‘leaf 
blight” or ‘‘leaf mildew.” It has been known to botanists fora long 
time and has received many Latin names, but the one here adopted 
has been generally employed by mycologists since 1869. 
The distribution of this disease is co-extensive with the cultivation 
of the fruit which it attacks, although there may be a few favored 
localities where it has not yet appeared. Throughout the Eastern 
and Central States one is almost certain to find it in every orchard, 
and on the Pacific slope in California it is also frequent. For more 
than fifty years it has been knownin Europe. It has becomea serious 
pest in Australia, and we now possess reports of its presence in New 
Zealand. 
Closely allied species, or, perhaps, only forms of the Apple Scab 
fungus, infest our native thorn trees and other natives botanically 
related to the apple. 
A fungus of such economic importance has, as may well be sup- 
posed, received much attention from our horticultural writers, and 
numerous papers relating to it are scattered through our horticult- 
ural journals and the reports of horticultural and agricultural 
societies. Some of the more important of these are mentioned below. 
For a long time the fungus on the leaf causing the “‘leaf blight” 
or ‘‘leaf mildew” and that on the fruit causing the ‘‘scab” were re- 
garded as distinct species. It was suggested by Prof. M. C. Cooke 
in 1873 that they were identical, and subsequent investigations have 
fully confirmed this view. 
(b) EXTERNAL CHARACTERS OF APPLE SCAB. 
On the leaves.—There first appear very small olive-green spots 
with a definite and rounded outline (Fig. 2). - As these increase in 
size, their surface assumes a velvety appearance and their borders 
Wallroth: Flora Cryptogamica Germa- @ 
