among the first of the aerial dusters where the delta puffers the puffers were an early airplane built by half the land and designed specifically for dusting work they take their place today among the aviation pioneers it was a new industry agricultural aviation they hired a new industry however and getting at the foundation upon which to build was agricultural research the u s department of agriculture evaluates new agricultural chemicals the chemical preparations are used to kill insects and to change the growth of plants the chemical industry supplies the u s d a and also the food and drug administr with samples of their products for evaluation with herbicides the weed killers screening and evaluation extends to field plots where plant varieties are correlated with families of chemicals aerial application of agricultural chemicals is approaching fifty million acre years annually aerial dusting and spraying has become a specialized field combining agriculture and aviation agricultural aviation has had its problems the lack of control in spraying has been largely overcome by experience the weight of pre war insecticides was overcome by research and an air of new agricultural chemicals improved metering devices have been developed by the people of agriculture and aviation working in close association work has been done by agricultural colleges by u s d a experiment stations by general aviation and the chemical industry field procedures for the measurement of distributed chemicals of been establ work has been done on the aerial distribution of fertilizers and seeds and aviation equipment has been developed to meet the needs much experiment continues with the airplane itself the worst enemy of the ball weevil is good farming practices it pays to keep a weekly count on the ball weevil population in the cotton frequent application of insecticides can control the weevil aerial dusting makes it possible to avoid tractor damage to the crop picking time means pounds per acre the result of correct planting fertilizing cultivation and insect control applied by airplanes in the san joaquin valley of california the following answer applied by helicopter helicopters are liked by the cotton growers for their application control however their high cost limits their use this is another problem of agricultural aviation yet to be overcome may be necessary in order to enable a mechanical picker to proceed through a field of rank and method cotton so it was here with this fiber crop that the industry of agricultural aviation found its beginning in the northwest agricultural aviation is valuable to the fruit industry in particular is the apple growers problem of windfall damage and normal pre harvest drop the fallen apples  in this work the helicopter has proven practical in an average year the saving of three apples on each tree pays for helicopter and chemicals the application may save up to forty percent of the crop depending upon conditions one chemical material widely used is a growth regulator two for five t p it is a factor for as long as a month it is important to spray the trees while the leaves are still working and it is important to harvest the fruit the proper maturity plant regulator sprays like two four five t p are used only for the effect they have upon the plant they are not used to poison insects for plant disease while their use is very specific the result for the grower is broad less dependence upon nature and more control and managing his crop one crop protected by aerial spraying and dusting is tobac ultimately camouflaged the tobacco horn worm can rapidly destroy a crop various insecticides can be used to control this field peste and insect infestation can readily crop the productivity of this field current has been destroyed by an outbreak of grasshoppers grasshopper outbreaks going to occur in range land or a variety of field crops this is insect damage to a tobacco leaf in sat down and these can be controlled by the aerial application of insecticides spray pests before damage to a crop is done insecticides are poisons growers of tobacco and food crops are required by law to use them within the established residue tolerances field tobacco for example is not sprayed with  within fifteen days of cutting most insecticides kills warmbloods and cold bloods alike properly used they will not cause disease nor increase the susceptibility of disease in animal or man wheat land is wet in the early spring and temperatures low ranchers may put nitrate fertilizer on their fields the object is to produce an early crop majority and consequently more grain volume ranchers who regularly use agricultural aviation services often provide a landing loading strip