Insects and Diseases 
SYSTEMATIC SPRAYING PLANS 
S. F. Poole, Winter Haven, Fla. 
Nearly three years ago Florida passed 
through a period of excessive rains lasting 
about a year. The trees were in good 
condition and carrying good crops up to 
the close of the rainy period. That fall 
complaints were heard from almost every 
section that the fruit was undersized. 
Still later in the season a gread deal of 
frenching appeared, much of which ac¬ 
companied withertip. 
Why some groves should show such 
exhaustion has been a problem over which 
I have pondered a good deal. In my notes 
reference is made only to groves that have 
come under my direct observation, though 
I presume that conditions such as were 
found existed in other parts of our State. 
Withertip is a disease that gains entrance 
into the tissues of a tree when its vitality 
has been lowered by neglect or starvation. 
But you could hardly say that these groves 
had been neglected. They were cultivated 
and fertilized as they had been for years. 
On the other hand, some groves in the 
same neighborhood did produce large 
crops of fruit of normal sizes, and did not 
reveal unusual withertip conditions. 
A close inquiry into conditions revealed 
practically the same cultural methods for 
both, but there was a wide difference in 
the purposes of fertilization, as well as 
in the sources from which the fertilizer 
ingredients were taken. The former peo¬ 
ple had been applying fertilizer twice or 
at the most only three times a year. The 
ingredients were fairly soluble. The oth¬ 
er people made four and even five appli¬ 
cations of a fertilizer that was not entirely 
or even readily soluble. The latter peo¬ 
ple had a food in the soil that was not 
easily dissolved and washed away by a 
period of excessive rains. With the for¬ 
mer system of two or three applications 
of a readily soluble fertilizer the trees were 
subjected to periods of starvation. The 
soil, at least in one respect, is like the 
human body in needing reserve energy in 
order to afford trees a continuous supply 
of food. The man who consumes all his 
bodily energy as fast as it is produced 
will soon need a doctor, so the soil that 
receives only two or three applications of 
a fairly soluble fertilizer will be unable 
to sustain trees at the close of an unusu¬ 
ally wet period. Consequently the ap¬ 
pearance of. frenching as a forerunner of 
withertip. The present spring may result 
in fresh inroads of withertip, especially in 
young trees. The growth has been inter¬ 
rupted many times by cold weather and 
undoubtedly weakened. 
Last summer there appeared in and 
around Winter Haven what seems to be a 
new disease. Fortunately, it is very slow¬ 
ly contagious, though it may make quick 
work of a tree when once fastened on to 
130 
