BULLETIN 756, U. S. DEPARTMENT OF AGRICULTURE. 
ism was associated with the diseased trees and indicated rather 
definitely that the cause of the trouble lay in the soil ; but whether 
this cause was physical, chemical, biological, or a combination of 
the three was not indicated. 
PRESENT INVESTIGATIONS. 
In 191l investigations of the disease were taken up by the writer, 
and an effort was made to find some common factor running through 
a large number of cases. Without such a common factor an infinite 
variety of empirical 
experiments was the 
only recourse. With 
this preliminary 
problem in mind, the 
examination of a 
large number of af- 
fected orchards was 
u n cl e r take n. Or- 
chards between cen- 
tral Florida and east- 
ern Louisiana were 
visited, and while the 
disease was seen to 
be present on a wide 
range of soil types 
and under various 
conditions of culti- 
vation and fertiliza- 
tion, one factor 
seemed to stand out 
prominently. 
THE COMMON FAC- 
TOR IN PECAN 
ROSETTE. 
Fig. 1. — A typical badly rosetted tree in one of the stable- 
manure plats in September, 1915. The same tree is shown 
in figures 2 and 3. 
A marked differ- 
ence in the amount 
of the disease in dif- 
ferent localities was 
found. On the river flood-plain soils of southern Louisiana the 
disease is practically unknown. Only two individual cases have ever 
been reported to State or Federal pathologists from that State. The 
soil is deep and black, of high fertility, and presumably of high 
water-holding capacity as compared with the typical sand, sand- 
