The Government experiments got under way, and specialists in fields and laboratories worked on the prob lem, first at Victoria, Texas, then Dallas and finally Tallulah, Louisiana. At last from the Government Wee vil Laboratory, the Experiment Farm at Tallulah, Louisi ana, came announcement of the long-awaited weevil cure. The patient researches of Professor B. R. Coad had discovered that the weevil, for all his boring into the depths of the boll, had a tendency to seek moisture wherever it could be found on the cotton plant. He arrived at the plan of dusting a rather virulent poison, calcium arsenate, on the plant while it was covered with dew. The dust sticks and each bath of moisture attracts the weevil to his death. The application can be made with effect only when the plants are damp and the at mosphere is still, preferably at night.
Mr. Coad was sure he had found the answer to the cotton disaster, but the solution awaited a machine for distributing the dust. The machine method of covering large acreage was the more needed because many plant ers were convinced that to turn dusting by hand over to unskilled Negro tenants might mean ruin. Hand guns were worked out but proved slow, difficult to operate, and liable to breakage. They sold from $12 to $20 each, and usually lasted only one season. The first machines were failures. Many of them were made, it is said, by men who never saw a cotton field. Those with gasoline motors were unsatisfactory "because operation at night necessitated more expert labor than was available." a One- and two-mule machines which apply the power for the spraying device through the axle work well. The one-mule machine, operated as one would a walking cul tivator, cost from $75 to $125, and was able to cover from 15 to 20 acres of cotton a night." In 1918 Coad issued his first pamphlet on the method. It aroused almost universal interest throughout the South. Calcium arsenate was difficult to make, and only one manufacturer was engaged in producing it on a com mercial scale. The next year three million pounds were produced and 75,000 acres treated. The first dust con tained so much water soluble arsenate as to burn the plants. When this danger was avoided the chemical some times failed to contain enough to injure the weevil. At Tallulah samples from farmers were analyzed. The Fed oral Insecticide and Fungicide Bureau also sampled large shipments and condemned the defective lots. Machines were worked out by department designers and the models were covered by patents dedicated to the public. Blue prints of these patents were sent to all interested man ufacturers." After the difficulty with calcium arsenate and machines, Coad announced two principles in the 1920 Yearbook.
First, "Raise a cloud of dust and let it settle." Second, "The weevil can be controlled by means of calcium arse nate dust if the dust is applied at the right season at the right interval and in the right way." The difficulties exist in the fact that the control does not last long after the poison is applied and that the weevils are reduced, never exterminated. It proved useless to attempt to get weevils early in the season. The greatest difficulty was found in attempting to tell when to start and stop poison ing." In 1922 Coad decided calcium arsenate was beyond the experimental stage and turned the method loose to go of its own momentum.
As weevil prevention became a standardized technique it was thought that the menace of the insect would be removed from the risks of production and become a stand ard item in the cost of production. The Department real ized this when it advised against the use of the method unless the yield per acre is at least a third of a bale and the cost of application not more per acre than the price of a hundred pounds of seed cotton." Coad and the great Scott Plantation, Mississippi, man aged by the Delta Pine and Land Company, dusted 13,800 acres of cotton at a cost of $4.04 an acre in 1922, Later they figured the cost at $2.50 to $3.00 per acre, counting that as part of the regular crop expense." Five to seven pounds of arsenate are required per acre, although weather conditions may increase the number of applications necessary. It was advised that poisoning operations be started when about 10 to 15 per cent of the squares are punctured.
Carrying his experiment further, Coad hired five army airplanes to dust 3,000 acres. It was found that the back rush of air broke the dust into clouds of fine particles, scattering it effectively. The tremendous friction elec trifies the dust particles. The plants serve to ground the electric charges. Thus the particles are attracted to the plants and cling closely. In this way the fields can be dusted during the day. It is not necessary to wait for the dew. The field was dusted more cheaply than it could have been by the forty machines, forty men and eighty mules required for 3,000 acres of cotton. Congress, it is suggested, should make appropriation for further ex periments. In the meantime several commercial companies have been formed for dusting cotton fields by airplane. It may prove cheapest to poison the weevil by airplane if all the farmers organize on a community basis to secure the services of the commercial company.