Florida Agricultural Experiment Station


 CANKER
 Caused by Phytomonas citri (Hasse) Com. S. A. B.
 Canker is the worst disease of citrus trees that has ever been
introduced into the Gulf States and, had it become well estab-
lished in Florida, it would undoubtedly have caused disastrous
results to the citrus industry. Fortunately, the serious nature
of this disease was early recognized and sufficient sentiment was
created to undertake its complete eradication. Between 1914
and 1931 more than $2,500,000 of state, federal, and private
funds were spent in combatting citrus canker in Florida alone
and the total cost of this disease to the state thus far has been at
least $6,500,000. During this period 257,745 grove trees and
3,093,110 nursery trees were destroyed incidental to the eradi-
cation of this disease, which occurred in 515 properties scattered
through 26 counties. Through the effective control campaign
and systematic inspection of grove properties carried out by
the State Plant Board, it appears that canker has been eradi-
cated in Florida. As a result of this energetic campaign, there
has been no commercial damage to Florida citrus groves by this
disease since 1922, and no infections have been found since 1927.
The apparently complete eradication of this dreaded disease
from Florida, Alabama, and Mississippi is one of the most out-
standing accomplishments in the history of plant disease control.
Constant viligance is necessary, however, to be sure that the
disease does not obtain another foothold.
 Canker is widely distributed throughout the citrus-growing
countries of the world but is especially prevalent in the Orient.
It is usually believed to be native to China but has also been
present in Japan for a considerable length of time. This disease
was first introduced into the United States in 1910 or earlier
on trifoliate orange trees shipped from Japan to Texas, Missis-
sippi, Alabama, and Florida. In Florida it was probably first
introduced from shipments of trifoliate orange trees from both
Japan and Texas and also from Satsuma orange trees imported
directly from Japan and planted at Monticello in the spring of
1910. When the disease was first observed in Florida by E. W.
Berger at Monticello on September 30, 1912, it was considered to
be scab, but when found again at Silver Palm in Dade County
in July, 1913, it was realized that a new disease had been dis-
covered. It was not generally recognized until 1914, however.