Some Citrus Diseases 
Prof H. E. Stevens. 
Citrus diseases have occupied public at¬ 
tention for a number of years. Much 
has been said and written on this subject,- 
valuable information concerning the na¬ 
ture and cause of these diseases has been 
collected, and in many cases practical 
methods looking toward their control have 
been worked out. But the subject has by 
no means been exhausted, and there is 
still much work in this field for future in¬ 
vestigation and practical application. 
I will not attempt to take up the whole 
field of citrus diseases but confine my re¬ 
marks to some that have been unusually 
troubleome this past season, namely, 
Melanose and Scab. 
MELANOSE. 
Phomopsis Citri Fawcett. 
This disease has been of special inter¬ 
est to us the past season, since it was on 
the 5th of last August that I succeeded 
in discovering the cause. A full account 
of the disease and of our investigations 
has been published in Bulletin 111, of 
the Florida Experiment Station. 
Melanose has been known in Florida 
for more than twenty years, but it«= place 
of origin and time of introduction into 
the State are not cpiite clear. Glancing 
over the history, we find the disease was 
first discovered by Webber and Swingle 
at Citra in 1892. Later it appeared 
around Ocala, Stanton, and Sanford, 
where it was reported as causing consid¬ 
erable damage. 
Webber and Swingle studied and de¬ 
scribed the disease, but were unable to 
find the cause. However, they concluded 
it was parasitic in nature, since it yielded 
to treatment with fungicides. From these 
centers, Melanose continued to' spread, 
and was reported from many localities in 
the State. Later it was thought that 
Melanose might be due to some physiolog¬ 
ical cause or some condition, of the soil. 
Prof. B. F. Floyd, of the Experiment 
Station, took up the work from this view¬ 
point, and made an extensive investiga¬ 
tion of the disease. His results led him 
to conclude that Melanose was caused by 
some parasitic organism such as a fungus 
or bacterium. 
In the spring of 1912 a biological study 
of Melanose was begun to determine, if 
possible, the exact cause. While the 
character and habits of the disease had 
been rather thoroughly worked over up 
to this time, previous investigators had 
been unable to find the cause. Inquiries 
and investigations showed that the disease 
was widespread and rapidly increasing. It 
is found in nearly all ‘citrus-growing lo¬ 
calities today, and I doubt if there is any 
grove in the State that is entirely free 
from it. 
