Keywords: herbicide sprayer
Description: Uniform application of chemicals at proper rates is essential for effective pest control. A slight variation in the rate of application with some chemicals may result in poor control of the pest or
Uniform application of chemicals at proper rates is essential for effective pest control. A slight variation in the rate of application with some chemicals may result in poor control of the pest or injury to the crop or the environment, causing a loss of time, effort, and money.
Herbicide rates may be given in terms of active ingredient or acid equivalent per acre treated, or as pounds or volume of commercial product per acre.
Active ingredient indicates the amount of non-acid herbicide in a formulation. Acid equivalent indicates the amount of an acid herbicide in a formulation.
Herbicides may be applied broadcast (uniformly over the entire field surface) or in bands (narrow strips of herbicide centered over the row with the area between rows left untreated). The rate of application in the treated area should be the same for the band as for the broadcast application. The amount of herbicide needed can be reduced by as much as two-thirds by banding the application over the row and controlling the weeds in the middles with mechanical cultivation.
For example . A 3-pound-per-acre rate requires 3 pounds of herbicide for each crop acre in a broadcast application; but only one pound is needed to apply the herbicide in 10-inch bands on 30-inch rows. To calculate the amount needed for band application, multiply the broadcast rate by the band width divided by the row width.
Commercial products contain differing amounts of active ingredients or acid equivalent. The amount of herbicide formulation to use per acre may be given on the product label. If you have to calculate from the active ingredient amount, use this method:
Divide the pounds per acre of active ingredient by its concentration in the product. If 3 pounds of active ingredient are needed per acre, and the product is an 80 percent powder, then divide 3 by 0.80 to get 3.75 pounds, the amount of powder needed per acre.
For liquids, the concentration may be given in acid equivalent. Then divide the pounds per acre of acid equivalent needed by the pounds per gallon contained in the product.
For example . If 3 pounds-per-acre of acid equivalent are needed, and the product contains 2 pounds-per-gallon, then divide 3 by 2 to get 1.5 gallons-per-acre, the amount of product needed.
After you have calibrated the sprayer to know your application rate in gallons-per-acre, divide that number into the gallons applied with each tankful to find the acres covered with each tankful. Then multiply the acres-per-tank by the herbicide needed per acre to find the herbicide to put in each tankful.
For example. Assume you have a 30 ft. sprayer that holds 500 gallons, and you want to apply an herbicide at 3 pounds of active ingredient per acre. The product comes as an 80% wettable powder. You calibrate your sprayer on a 300 foot course and apply 4 gallons of spray to the course.