40 BULLETIN 1204, U. S. DEPAKTMBNT OF AGRICXJLTUKE. 
as much area for the season as at least 40 cart dusting machines, 
which have the greatest acreage capacity of any machines now 
used in cotton dusting. To operate these dusting machines of course 
requires considerable supervision, and a number of special expenses, 
such as fuel for Lights, etc., but, considering only the value of man 
labor and mules alone, it would cost $236 a night to operate these 
machines. On this basis considerable economy in favor of the plane 
would be indicated. The cost of the plane and its upkeep in repairs 
would apparently figure no more than the original cost plus up- 
keep of the dusting machines which it would replace. Consequently, 
it seems possible that the cost of equipment, if each is allowed full 
acreage would be about the same as for ground dusting machines, 
and the operating expenses would be lighter with the airplanes than 
with the ground machines. Furthermore, all work which has been 
conducted seems to indicate that the poison required per acre can 
be greatly reduced with a plane as compared with the ground ma- 
chines, and this would be a very important item, since the cost of 
poison is by far the heaviest expenditure involved in dusting cotton. 
CONCLUSIONS. 
The studies which have been described are far from deciding on 
the practicability of using the airplane for applying insecticides, 
but they have shown that the dust can be blown down among the 
plants from the air above them and that this dust can be made to 
adhere to the plants under daytime conditions when plane operation 
is feasible. The planes can be manipulated so that all portions of the 
field are treated. In fact, the cotton leaf worm was controlled with a 
poison allowance considerably below that necessary when using or- 
dinary dusting machines. Whether this application was sufficiently 
thorough to control the boll weevil is quite another question, since 
weevil control requires a much more thorough application than is 
necessary to control the leafworm, but all records bearing on this 
question appear to furnish decidedly favorable indications of success. 
Financially the use of the airplane does not seem to be out of the 
question, and in fact there is considerable possibility of pronounced 
economy as compared with the ground machines. It has the advan- 
tage of centralizing the control of the operation and placing it on 
a more skilled basis, which would undoubtedly greatly tend to in- 
crease the quality of the results secured. On the other hand, no 
farmer can afford to buy a single plane and figure on dusting his cot-" 
ton, since it is not safe to place all of the eggs in one basket in this 
manner. Motors will go wrong, and cotton poisoning is an opera- 
tion which can not be delayed when needed. The operation could be 
only considered as a community affair or for planters whose acreage 
would be large enough to justify purchasing more than one plane. 
In reality, to organize in safety, one plane should be provided in re- 
serve for every one or two which are kept in (light. 
All of these are questions which can be worked out only by time 
and trial, but many districts in the South have now reached the point 
in public sentiment where the desirability of community weevil con- 
trol can be seen, and it is only by some such method as the use of the 
airplane that such community poisoning can be attempted in the near 
I ut ure. 
WASH I \<; n>\ GOVERN MB NT PRINTING OFFICE : 1923 
