elf chemicals are to be used, only the minimum amount for optimum control should 
be used. To apply this optimum amount will necessitate an intimate knowledge of 
the characteristics of the plant, the insect, the disease, the particle characteris- 
tics, and the forces affecting deposition. 
elf chemicals are to be used, application of the right kind of chemical must be made 
in the right place, at the right time, in the correct amount, and properly distributed 
for the needs. 
PROBLEM NEEDS 
Application of pesticides is a subject concerned with several disciplines. However, 
many of the physical and engineering aspects can be considered in isolation from ento- 
mology and crop production, providing these aspects are treated in general terms. 
As stated in the introductory remarks, the usefulness of pesticide application is 
greatly affected by the equipment used. This is true whether the application is from the 
air, by ground machines, or under the soil surface. 
The primary purpose of basic agricultural engineering researchon pesticide applica- 
tion is to gain information on fundamental principles and equipment requirements which 
ultimately will be made available to manufacturers. Agricultural engineers also have an 
obligation to help implement the research of entomologists, crop and soil scientists, and 
economists. This is a continuing and in fact expanding need because of the rapidly changing 
circumstances resulting from changing crops, new cultural practices, new pests, new 
pesticides, and new materials of construction. We must emphasize that the existence ofa 
generally acceptable and widely used commercial machine fora particular farm operation 
is not proof that there is no need for further engineering research on this operation. 
It would be just as reasonable to argue that there is no need for further research in crop 
genetics because widely accepted varieties of wheat, corn, and cotton are available. 
The objectives of applied engineering research are to develop new and improved 
equipment and methods for more accurately directed and more uniform application of all 
types of pesticides, liquid, dust, granular, or biologic, to all important crops and animals. 
The results of such research will: 
(1) Reduce the pesticide residue hazard to man, animals, and beneficial insects by 
reducing the application rates required. 
(2) Reduce the danger of damage to crops or wildlife on adjacent areas. 
(3) Improve the control of pests. 
(4) Reduce the cost to farmers. 
In order to attain these results we must recognize the axiom that the application of an 
economical minimum amount of chemical over large areas will require the division of 
the pesticide material into very small, althoughnotnecessarily uniform particles. 
An examination of need shows that equipment must fulfill application requirements 
for at least the following situations: 
1. On plant surfaces, which includes: 
(a) run-off spraying 
(b) low-volume spraying 
(c) dusting 
(d) granular materials 
2. On the soil surface 
3. Under the soil surface--gaseous and volatile materials 
4. Other locations, such as on animals 
Cy! 
