62 
FLORIDA STATE HORTICULTURAL SOCIETY 
such cases. Proper insect control is the 
rational procedure. 
Another limitation is the difficulty of 
securing a perfect coating of fungicide. 
Any uncovered spot is a break in the de¬ 
fensive armor and with the enemy spores 
numerous enough there will be a certain 
number of infections. These spores are 
so minute that 10,000 of average size 
can lie side by side in a single layer on the 
head of a pin. Carefulness in handling 
the spray rod is the best corrective. Have 
an engine and pump that will develop 150 
to 200 pounds pressure, and keep it there. 
Use a nozzle that throws a good misty 
spray, and renew the disc frequently to 
keep it so. Use a disc with a small 
enough hole to make a fine spray, and 
thin enough to throw it in a wide cone. 
Use angle nozzles, a cluster of two for 
larger trees. Cover the tree evenly and 
completely, as though painting a house, 
trying to hit every part from two direc¬ 
tions, which may be done by a slight turn 
of the angle nozzle. Thrusts and turns in 
the tree’s interior help complete coating. 
Cover the lower sides of leaves and the 
upper sides will usually be taken care of. 
Remember that the uncoated parts will 
determine the amount of loss, other 
things being equal. 
Still another limitation is the weather¬ 
ing or washing away of spray solution af¬ 
ter it is properly applied. The application 
must be repeated often enough to main¬ 
tain a good coating at the critical times; 
and these are determined largely by 
moisture conditions during the general 
period when the hosts are in a condition 
of susceptibility and when the fungus 
spores are disseminated. Have a mix¬ 
ture of good adhesiveness on when the 
rains come, rather than afterwards. If 
unfortunately caught without such pro¬ 
tection, spray immediately afterwards. 
Every hour even may count. The usual 
procedure is to follow a schedule of ap¬ 
plications, intended to afford continuous 
protection during the danger period, 
lengthening the intervals somewhat under 
dry conditions and shortening them under 
wet. Do not be misled by sediment that 
may have lost its fungicidal properties. 
Consideration must also be given to the 
rapid increase in size of young parts, and 
the necessity for keeping them covered as 
they grow. 
The spray solution must be chosen with 
reference to its effectiveness against the 
fungus in question, its non-injurious ef¬ 
fects on the host, together with reason¬ 
able cost and ease of preparation. An in¬ 
effective material is dear at any saving in 
money or trouble. There is a natural 
tendency to unduly magnify differences in 
cost of materials. Figure them down to 
the cost per box of fruit and see what 
they really amount to. Injuriousness in¬ 
cludes the matter of direct spray injury 
which may sometimes be as objectionable 
as the disease itself; and also the indirect 
effect of spraying on the insect-destroy¬ 
ing fungi, that are to be safeguareded as 
much as is practicable. Effectiveness de¬ 
pends in the main on killing power for 
the fungus in question, with a very im¬ 
portant consideration of the proper bal¬ 
ance between immediate action and ex¬ 
tended duration of effect. As a rule, 
spray coatings that are easily redissolved 
in atmospheric water have a high initial 
fungicidal power, with a tendency to- 
