6 BULLETIN 1118, IJ. S. DEPARTMENT OF AGRICULTURE. 
Swingle and Webber (28, p. 20-24) were the first to conduct 
extensive field studies and spraying experiments for the control of 
scab. They attribute its cause to a species of Cladosporium and 
state that so far as is known this fungus is found only on citrus plants 
affected by this disease. A description of this fungus and spore and 
hypha (sporophore ?) measurements are recorded, as well as the 
varieties attacked and conditions under which infection takes place. 
They consider that this disease was undoubtedly introduced into 
America on the Satsuma orange (budwood) from Japan. Copper 
sprays were found effective against this disease. 
Massee (12, p. 310-311) attaches the specific name u citri pro tern." 
to the generic name Cladosporium, not for final acceptance but for 
convenience in reference. He gives Swingle and Webber's measure- 
ments of spores and sporophores and adds a brief description of their 
form. Briosi and Farneti (1) describe the ruggine bianca of lemons 
in Sicily and state this disease is caused by Rhynchodiplodia citri, 
having several conidial forms, among them Cladosporium citri. This 
organism differs but little from C. citri occurring in Japan and 
America. 
In order to correct the confusion between Cladosporium citri 
Massee and C. citri Briosi and Farneti, Saccardo (18, p. 1366-1367) 
gives to the latter species the name C. farnetianum and records the 
former as C. citri Massee. 
In March, 1906, Fawcett (2) isolated a hitherto undescribed fungus 
from sour-orange leaves. He made mention of certain of its cultural 
characters and used the name Cladosporium citri in connection with 
this new organism. In a later publication (3) he calls attention to 
a series of errors which had crept into the literature in regard to the 
confusion of C. elegans Penz. with C. citri pro tem. Massee. Still later 
Fawcett (4) proved by a series of inoculations that the scab is caused 
by the fungus found by him in scab lesions as early as March, 1906. 
The characters of this true citrus-scab organism were illustrated and 
again described. Unfortunately this pathogen was left without a 
name to distinguish it from the saprophytic organism illustrated by 
Scribner (20) and described by Swingle and Webber (28, p. 20-24) 
and by Massee (12, p. 310-311). The result is that two organisms, 
very distinct in morphological and cultural characters (the one a true 
parasite, the other a saprophyte) have been referred to in the literature 
as Cladosporium citri Massee. Attempts to find a perfect stage of 
the true citrus-scab fungus were made by Fawcett without success. 
Citrus plants subject to attack by this fungus are mentioned and 
control measures based on spraying experiments suggested. 
Stevenson (24) emphasizes the influence of weather on citrus-scab 
outbreaks. His experiments for control show that in Porto Rico (26) 
sulphur sprays were partially effective against citrus scab, while 
