100 
ANTHRACNOSE OF COTTON.* 
(Plate IV.) 
By E. A. Southworth. 
This disease, like others of the same name, is exceedingly destructive 
to the plants which it attacks and is caused by a fungus resembling 
the Glceosporiums. The presence of dark colored setra among the 
spores and basidia separates it from the genus Gloeosporium and makes 
it a CoUetotrichium , but the general character of the fungus, so far as 
its effect on the host is concerned, is very similar to that of the Gloeo- 
sporiums, well known as Authracnose of the grape and raspberry. In 
the cotton fungus the setae do not at first develop in any numbers, but 
become very numerous as the fungus grows older. 
When the fungus was first brought to our notice, some immature 
specimens were sent to Mr. Ellis, who afterwards sent them to Mr. 
Cooke 5 both agreed that they were identical with Gloeosporium carpi- 
genum , Ck. & Hk., and the fungus was distributed in Ellis’s North 
American Fungi under this name. Through the kindness of Professor 
Harkuess I have recently been enabled to compare it with type speci¬ 
mens of G. carpigenum , and find it quite distinct from this fungus. G. 
carpigenum is a true Gloeosporium with no setae and the fruit borne in 
isolated pustules. The spores are also much smaller than those of the 
cotton fungus. These characters, as will be seen further on, separate 
the latter from Gloeosporium carpigenum and the possession of setae 
places it in the genus CoUetotrichium. There seems to be no record of 
any specific name ever having been given it and I will call it Colletotrich- 
ium gossypii.] 
EXTERNAL APPEARANCE AND EFFECTS ON THE BOLL. 
According to Mr. Atkinson, who has observed the disease in the field, 
the fungus attacks all parts of the plant. It has been sent to us, how¬ 
ever, only on the boll, and this description must therefore be limited. 
So far as can be judged from specimens that have been picked from 
* Since this article was prepared, Professor Atkinson read a paper on the same sub¬ 
ject before the Association of American Agricultural Experiment Stations at Cham¬ 
paign, 111. The work in both cases was entirely independent, except where I have 
cited Professor Atkinson’s authority in regard to the parts of the host plant 
attacked.—E. A. S. 
t CoUetotrichium gossypii , n. s. On cultivated cotton, may occur on any part of the 
plant, especially injurious to bolls. Sori orbicular, dark colored, or covered with a 
pink powder. Acervuli erumpent, distiuct only when young. Spores irregularly ob¬ 
long, usually with a light spot in the center, often acute at oue end, colorless singly, 
flesh-colored in mass, borne on short basidia or long setie. Basidia colorless varying 
in length, at least longer than the mature spore, very rarely branched, borne on a 
stroma of varying thickness, 11-28 x 5/*. Setm occurring singly or in tufts, more abun¬ 
dant in older specimens, dark brown at base, but nearly colorless at the apex, septate, 
often irregular in outline, straight cr llexuose, rarely branching, often bearing spores. 
Mycelium septate, intra and intercellular, usually colorless, producing secondary 
dark colored spores, especially when it has simply the form of a germ tube. Stroma 
of varying thickness, often penetrating the plant tissues for some distance, becoming 
dark colored with age or where seta? are borne. 
