FLORIDA STATE HORTICULTURAL SOCIETY 
37 
SOME DISEASE PROBL EMS OF THE SEASON 
H. E. Stevens 
Mr. President, Ladies and Gentlemen: 
Ordinarily the citrus grower has his 
attention reasonably well occupied in at¬ 
tempting to combat the various pests he 
finds in his grove. This season, how¬ 
ever, his problems will be greater and he 
will find that his labors have been in¬ 
creased many-fold. Owing to conditions 
that have come about within the last few 
weeks, it will be found necessary to give 
the citrus groves more than ordinary at¬ 
tention through the present season; not 
only in the matter of fertilizing and culti¬ 
vating the trees, but in keeping down in¬ 
sects and preventing as far as possible, 
some of the more common diseases. 
In many parts of the State citrus trees 
were severely injured by the low temper¬ 
ature that occurred in early February. 
Heavy losses have been reported from 
some sections of the State and in general 
citrus trees have been greatly weakened 
through the effects of the freeze. 
Trees in this condition will be more sus¬ 
ceptible to the attacks of certain fungi and 
unless they are given more than ordinary 
attention still greater losses are possible. 
A considerable amount of pruning and 
spraying will be necessary to hold these 
diseases in check until the trees have re¬ 
covered their former vigor. 
While I can hardly regard the recent 
freeze as a blessing in disguise, especially 
as to its ultimate effect on citrus diseases, 
yet conditions were afforded in many in¬ 
stances whereby insect pests and fungus 
diseases could have been completely erad¬ 
icated with but very little effort. Leaves 
and fruits affected with diseases and in¬ 
sect pests have been killed by the freezing 
temperature. Through defoliation and 
dropping of such fruits a large amount of 
infectious material has been carried out 
of the trees. If this has been properly 
disposed of, either burned or buried, a 
long step has been taken toward the erad¬ 
ication of such pests. 
Again, the low temperatures have given 
a decided check to the development and 
spread of certain fungus diseases. This 
however, is only of a temporary nature. 
As a rule fungus spores are not killed by 
freezing and they have withstood the low 
temperatures much better than the citrus 
tree. They will rapidly recover from 
their temporary set-back and they will be 
in an active state to affect the tree while 
it is still in a critical condition. 
On the other hand the weakened condi¬ 
tion of the citrus tree as a result of the 
low temperatures will leave it more sus¬ 
ceptible to fungus attacks. The sudden 
checking of the growth, the loss of foli¬ 
age, and the large amount of dead wood 
and weakened branches, have all tended to 
make an enormous drain on the vitality of 
such trees. Unless this vitality is restor¬ 
ed as soon as possible, diseases will enter 
to further complicate mattters which may 
finally result in the destruction of many 
valuable trees, or in a greatly inferior 
crop of fruit. 
