20 



placed that the resulting larvfe would be more or less subject to poison- 

 ing, if poisons were present on the plants. As bearing on this point 

 the following experiments are of interest: 



During June, a cotton plant bearing numerous squares, flowers, 

 and bolls, was sprayed with Paris green at the rate of 1 pound to 100 

 gallons of water. A few hours later 100 larvte, just hatched, were 

 distributed over the plant, which was then covered with a large wire- 

 screen cage for protection. Subsequent examinations did not reveal 

 any bollworms whatever on the plant, the larvse doubtless being all 

 destroyed by the poison. 



A similar test was made during August, but only 50 young larvte 

 were used. Out of this number but one bollworm survived, which was 

 found when about two weeks old feeding on a half -grown boll. 



Field experiments with poison were conducted at Hettj^ and at Cal- 

 vert, Tex., and, although started somewhat late, nevertheless gave 

 decidedly favorable results. 



At Hetty, a 10-acre cut of uniform, late, native cotton, growing on 

 bottom land, was selected, 5 acres of which was poisoned and 5 acres 

 was left unpoisoned, as a basis for comparison. Paris green was 

 dusted freely over the plants by the usual dusting method, namely, 

 from bags on the ends of a short pole carried by a man on horseback. 

 Applications were made August 22 and 31 and September 8, using 

 approximately 3 pounds of the "green" per acre at each dusting. 

 The results are indicated in the following table: 



Compariwn of yields from plat dusted with Paris green and plat left untreated. 



Yield from poisoned 5-acre plat pounds seed cotton . . 2, 720 



Yield from unpoisoned 5-acre plat do 1, 434 



Yield in favor of poisoning do 1,286 



Value of excess, at 3 cents per pound of seed cotton $38. 58 



Cost of 45 pounds of Paris green, at 18 cents per pound $8. 10 



Cost of labor, one man three mornings, at 50 cents per morning 1. 50 



Total cost of poisoning 9. 60 



Net gain per acre in favor of poisoning 5. 79 



At Calvert poisons were applied by the dusting method and also b}' 

 means of a spray pump. The spraying was done with a barrel sprayer 

 furnished with two leads of hose and four nozzles. A team, wagon, 

 and two men were required, one man to drive and pump, the other to 

 handle the nozzles at the rear end of the wagon. "Green arsenoid" 

 was used, at the rate of 1 pound to 50 gallons of water, which would 

 poison approximatel}^ 1 acre. With water one-half mile distant, onl}^ 

 5 to 6 acres per day could be spraj^ed. With a more convenient water 

 supply and with geared spraying machinery, the ground covered per 



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