14 MECHANICAL CONTROL 



CALCULATING SPRAY APPLICATIONS 



r Based largely on Suggested Guide for Chemical Control of Weeds, U. S. Agr. Res. Service Special"! 

 I Report 22-23, April 1956. Useful information on calculations and procedures in aerial spraying is I 

 Lgiven in How to Spray the Aircraft Way, USDA Farm. Bui. 2062, June 1954. J 



The amount of herbicide delivered to a sample unit or area can be 

 determined preliminarily by a test run using plain water in the 

 spray tank. The method is applicable to various types of equip- 

 ment under particular conditions of nozzle adjustment, tank pres- 

 sure, and rate of progression. When a known acreage, fraction of 

 acreage, or other unit of area has been sprayed during a test run, 

 the amount of water used can be ascertained by measuring the 

 quantity required to refill the tank. In making calculations for 

 different operations, rate of progression or nozzle adjustment may 

 need to be altered if plants to be sprayed are of different height 

 or density. 



The number of gallons per acre applied by a power sprayer, at a 

 given setting of nozzles, tank pressure, and rate of progression, can 

 be determined after a 220-yard test run as follows: Multiply the 

 number of gallons used by 66 and divide the product by the number 

 of feet in the sprayed strip width. Similarly, for a 110-yard test, 

 multiply the gallons by 132 and divide by the number of feet in the 

 sprayed strip width. 



The number of pints per acre applied by a full 3-gallon hand 

 sprayer can be calculated by testing on a 10 x 10 foot (100 square 

 feet) area as follows : 1/2 pi^^t applied to 100 square feet equals 27 

 gallons per acre, 1 pint equals 55 gallons per acre, and one quart 

 equals 110 gallons per acre. Accordingly, if one wishes to apply 

 1 pint of commercial weed killer per acre, it should be mixed with : 

 27 gallons of diluent if the sprayer applies 1/2 piiit to 100 square 

 feet, 55 gallons of diluent if sprayer applies 1 pint to 100 square 

 feet, and 110 gallons of diluent if the sprayer applies 1 quart to 

 100 square feet. 



MECHANICAL CONTROL 



Besides mechanical equipment used in spraying, machinery of 

 several types is of practical value in controlling weeds in marshes 

 and swamps and in converting such areas into cultivated fields or 

 marshes attractive to waterfowl. Equipment for such purposes 

 includes bulldozers for felling woody plants, rotary brush cutters, 

 heavy harrows, disks, and rototillers for conditioning soil that con- 

 tains masses of tough roots, and mowers or crushers for control 

 of coarse marsh weeds. A principal limiting factor to wider use 

 of such equipment is its inability to function well on soft, boggy 



