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Understanding your weed management options is a big responsibility for landowners. Local weed districts, your state department of agriculture, and the USDA-NRCS are valuable resources.

Below is a helpful reference for those who rely on chemical applications for weed control. Buying bulk chemical, mixing, and spraying is often effective, but only if you take precautions to use the right chemical in the right way. At Murdoch's our local team members can offer expert advice. We hope to be one of many resources available to you; we sell natural, organic, and synthetic control products.

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CALIBRATE FOR ACCUTRATE HERBICIDE APPLICATION

Accurate Herbicide Applications

We can’t control the weather or the plants’ readiness to absorb the chemical, but we can help you accurately control how much chemical you apply for the best results

CALIBRATE HANDGUNS FOR SPOT SPRAYING:

  • One gallon of water equals 128 oz.
  • We will use a test area that is 1/128 of an acre
  • Now we can calibrate using oz. of water collected to equal gallons-per-acre.

HERE’S HOW IT WORKS

  1. Measure out an area that is 18.5 ft. x 18.5 ft.
  2. Spray the area while recording the time it takes to cover it.
  3. Using a measurable container, spray for the same amount of time that it took to spray the test site.
  4. The number of oz. collected equals the gallons-per-acre that you are spraying.

EXAMPLE:

We measured and sprayed our area. It took 51 seconds to spray it. Spraying into our container for 51 seconds,we collected 40 oz. of water. We now know that we will be spraying at a rate of 40 gallons-per-acre.

With this information, we can calculate our mixing rate. If a chemical calls for 2 qt./acre, we divide 64 oz. (2 qt.) by 5,120 oz. (40 gal.) to calculate ounces of chemical/ gal. of water. In this case, it would be 64/5,120=.0125. If our sprayer is 14 gal. (1,792 oz.) we take 1,792 x .0125 = 22.4 or the number of ounces of chemical that we need to mix with water into our 14 gallon tank.

ALWAYS READ THE PRODUCT LABEL FOR COMPLETE APPLICATION INSTRUCTIONS AND SAFETY INFORMATION

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BOOM SPRAYER CALIBRATION

Boom Sprayer
  1. Determine nozzle spacing.
  2. Refer to the following chart to determine calibration course: +To determine the length of the calibration course for a nozzle spacing not listed, divide 340 by the spacing expressed in feet. Ex: Calibration distance for 19-inch nozzle spacing = 340 divided by 19/12 = 215 feet.
  3. Measure and stake off the appropriate calibration course based on nozzle spacing. The course should be on the same type of ground as that to be sprayed (Speeds may be faster on roads than on sod, changing the application rate.).
  4. Drive the course in the gear and rpm you will use when actually spraying. Record the time in seconds. Do this twice and average the time.
  5. Park the tractor and maintain the same rpm.
  6. Turn on the sprayer and catch the water from one nozzle for exactly the same number of seconds that it took to drive the calibration course.
  7. Ounces caught = gallons per acre.
  8. . Check all nozzles. Flow rate should not vary more than 10% among all nozzles. Clean or replace any nozzles that do not fall in this range.

BOOMLESS SPRAYER CALIBRATION

Boomless Sprayer
  1. Measure effective swath width.
  2. Refer to the following chart to determine calibration course: + To determine the length of the calibration course for a swath width not listed, divide 5,460 square feet (1/8 acre) by the swath width in feet. Ex: Calibration distance for 32-foot swath width = 5,460 divided by 32 = 171 feet
  3. Drive the course in gear and rpm you will use when actually spraying. Record the time in seconds. Do this twice and average the time.
  4. Park the tractor and maintain the same rpm.
  5. Turn on the sprayer and use a trash bag and bucket to catch water for exactly the same number of seconds required to drive the calibration course.
  6. Pints caught = gallons per acre.

+ Source Texas Agrilife Extension

Disclaimer

Murdoch’s does not recommend using any residual herbicide on hay, silage, or hayledge that will be distributed, made available for sale, or moved off the farm or ranch where harvested.

Murdoch’s does not recommend using forage, straw, or manure from any herbicide treated area (including pasture) in compost or other garden amendments. Spread treated forage, straw or manure only on rangeland/pastureland, or non-susceptible crop areas.

Residual herbicide levels in manure and urine excreted from animals consuming treated forage (including pastureland) may contain enough herbicide residual to damage non-target plants. Herbicides cause no harm to grazing animals and pass through their digestive tract unchanged in three days. Provide three days of untreated forage before moving animals to sensitive crop areas.

For specific information and application directions, please read and follow the product label instructions or ask a Murdoch’s associate for help.