84 
FLORIDA STATE HORTICULTURAL SOCIETY 
any material change in our present meth¬ 
od of handling this disease. Any practi¬ 
cal method of control other than eradica¬ 
tion, seems as hopeless now as before, for 
bacterial diseases do not yield to any treat¬ 
ment except complete destruction of the 
infected parts. 
Just why this particular fungus should 
occur so' generally in the canker infections 
is rather difficult to explain. It is proba¬ 
ble that it plays a secondary part in the 
development of many canker spots. Fur¬ 
ther investigation will determine this. 
DISSEMINATION 
Warm humid weather favors a rapid 
development of the disease, and thus it is 
more destructive during the rainy season. 
It is active, however, for the greater part 
of the year, especially in the southern part 
of the State where weather conditions are 
more favorable. It is spread mainly by 
some carrier. Insects, birds, other ani¬ 
mals, and man, coming in contact with in¬ 
fected foliage that is wet with dew or rain, 
may easily carry the disease to healthy 
trees. 
INJURY FROM THE DISEASE 
The injury from this disease may be 
considered as two-fold. The most appar¬ 
ent injury results from the spotting of the 
fruit, making it unsalable. Since the dis¬ 
ease spreads so rapidly and may attack the 
fruit at any age, practically all fruits on a 
badly infected tree would soon be reduced 
to culls. Canker does not cause a rotting 
of the fruits, or affect the interior of ma¬ 
ture fruits, other than opening the way 
for rot-inducing fungi which may enter 
and cause decay. Fruits that are badly 
attacked when young are apparently stunt¬ 
ed and fail to develop. 
That the'disease injures the tree seri¬ 
ously is evident. What the ultimate effect 
of the disease on the tree might be we do 
not know at present, for we have not had 
badly infected trees under observation 
long enough to tell. Our observations 
show that where trees are badly attacked 
there is a falling of the younger leaves 
and a perceptible stunting of the young 
twigs. Continued defoliation by the dis¬ 
ease would finally result in the death of 
the tree, or soon render it worthless. 
The serious nature of citrus canker can 
not be doubted by any one who has had 
experience with it, or who has seen its 
work. There has been some difference of 
opinion regarding the drastic methods of 
treatment employed against it, but since 
we are dealing with an unusual disease, 
drastic measures are necessary to stamp 
it out. This is by far the most serious dis¬ 
ease of the grapefruit that has ever ap¬ 
peared in the State, and it will shortly 
ruin the industry if allowed to spread. 
Let us examine some of the reasons why 
it is more serious than some of the other 
citrus diseases. 
First : It attacks all parts of the grape¬ 
fruit tree, the leaves, fruit, young shoots, 
and bark on larger branches and trunks, 
and even the exposed roots. 
Second : It does not yield to treatment 
with any of the known fungicides or any 
other so far as we know. 
Third : The disease is able to grow and 
spread throughout the entire year. 
Fourth : It is impossible to locate and 
remove all the infections that occur on 
the larger branches and trunks of dis- 
