88 
FLORIDA STATE HORTICULTURAL SOCIETY. 
thorough time. Of course, you must re¬ 
member that a man doing this work must 
be paid a good salary and it means the 
expenditure of a large sum of money and 
I would suggest that if the orange grow¬ 
ers can secure from the state legislature 
or underwrite it themselves, it would be 
possible to draw upon the Adams fund 
for a considerable amount, and I am sure 
both the federal and state authorities will 
co-operate with them. 
YELLOW SPOTTING OF CITRUS LEAVES. 
By B. F. Floyd. 
Mr. President , Ladies and Gentlemen : 
A greasy yellow spotting of citrus 
leaves has been reported to the experi¬ 
ment station from numerous localities in 
the citrus-growing belt of the State. In 
some cases, it apparently caused much 
damage. An investigation of this trouble 
was started in the laboratory of plant 
physiology in January, 1908. A close 
study has been made of the distribution 
and prevalence of this disease in Florida, 
and of its gross effect upon the affected 
trees. Its effect upon the leaf has been 
studied in the laboratory. Numerous at¬ 
tempts have been made to isolate organ¬ 
isms that might be the cause of the mal¬ 
ady. 
Very little is known of the history of 
this disease. It has been known for sev¬ 
eral years, but there are no reports of its 
presence previous to the freeze of 1894- 
95. There is no evidence that the disease 
originated in any particular part of the 
State. It may almost entirely disappear 
in localities where it has been present 
for many years, and appear again after 
an interval. This is perhaps due to vary¬ 
ing climatic conditions. 
From the evidence which has been col¬ 
lected, this disease belongs to the same 
class as Frenching, Melanose, Dieback, 
and Blight; all of which are due either to 
unfavorable soil conditions, improper 
treatment, or to as yet unknown causes. 
DISTRIBUTION. 
The Yellow Spotting of citrus leaves is 
met with in the State from the East Coast 
to the West Coast. It has been reported 
from Lake City in the North and from as 
far South as Miami. 
Its prevalence varies considerably in 
different groves in the same locality. In 
some groves or parts of groves, there 
may be only a few leaves affected on any 
tree, mostly in the upper portion of the 
tree. There may be many trees in be¬ 
tween the diseased ones, upon which no 
spotted leaves can be found. Other 
groves close by may have nearly eveiy 
tree affected, and on many trees a healthy 
leaf may be hard to find. 
In November, 1908, a careful survey 
