Hand-held and backpack sprayers are extremely useful for treating small turf areas infested with weeds. But they have to be calibrated to apply the recommended rate of a herbicide." /> Hand-held and backpack sprayers are extremely useful for treating small turf areas infested with weeds. But they have to be calibrated to apply the recommended rate of a herbicide." />

CAES Newswire

 College of Agricultural & Environmental Sciences UGA Cooperative Extension
Menu
Published on 02/16/04

Calibrate your hand-held, pump-up sprayer

Volume XXIX
Number 1
Page 30/i>

By Clint Waltz
and Tim Murphy
University of Georgia

Hand-held and backpack sprayers are extremely useful for treating small turf areas infested with weeds. But they have to be calibrated to apply the recommended rate of a herbicide.

Most herbicides used in turf grasses control weeds without injuring the turf. But that depends on the rate applied. The rate is usually on the product label as the amount to be applied to 1 acre or 1,000 square feet.

For example, the highest recommended rate of Trimec Classic for Bermuda grass and tall fescue is 1.5 fluid ounces per 1,000 square feet.

Applied at this rate and by the label directions, it will cause only slight injury to labeled turf grasses. But if you apply three times that amount, some turf grasses would be yellow or brown for weeks.

If a sprayer isn't calibrated, it can't apply herbicides at recommended rates.

It's simple

You can use a number of methods to calibrate sprayers. One that's simple, easy to do and easy to remember is called the 1/128th-acre method.

In this method, you spray 1/128th of an acre. That's 340.3 square feet. This figures out to 18.5 feet by 18.5 feet. Here's how to do it.

  1. Mark off a plot 18.5 feet by 18.5 feet.
  2. Fill the sprayer to normal capacity with water.
  3. Pump the sprayer to the pressure normally used to apply herbicides.
  4. Spray water over the plot area while maintaining normal and constant operating pressure.
  5. Record the time in seconds it takes to spray the plot area.
  6. Using the same constant pressure used in step 4, spray into a bucket for the same time (number of seconds) it took to spray the plot area.
  7. Measure the volume of water in fluid ounces.
The number of fluid ounces you collect is equal to number of gallons the sprayer would apply to 1 acre if you use it at the same pressure and walking speed you used in the plot area.

This quick conversion works since there are 128 fluid ounces in 1 gallon of water. It doesn't get much easier than this. Now all you have to do is find out how much herbicide to add to the pump-up sprayer.

How it applies

Let's say your sprayer applies 25 gallons per acre. The right rate for Trimec Classic is 4.0 pints, or 0.5 gallons, per acre. So divide 0.5 by 25 to get 0.02, or 2 percent.

Multiply that by the sprayer capacity. A 2-gallon sprayer would hold 256 fluid ounces, and 256 times 2 percent would be 5.1 ounces. So add 5.1 ounces of Trimec Classic to the sprayer. Then fill it to the 2-gallon mark with water.

Remember, you have to walk at the same speed, maintain the same pressure and hold the spray nozzle tip at the same height you used in the plot area.

If you do these things, you'll apply the recommended rate of the herbicide, control the target weed and, most important, drastically reduce the chance of injuring your turf grass.

(Clint Waltz is an Extension Service turf scientist and Tim Murphy an Extension Service weed scientist with the University of Georgia College of Agricultural and Environmental Sciences.)

Clint Waltz is a Cooperative Extension turf specialist with the University of Georgia College of Agricultural and Environmental Sciences.

Tim Murphy is a Cooperative Extension weed scientist with the University of Georgia College of Agricultural and Environmental Sciences.

Experts/Sources:
Clint Waltz
Tim Murphy
SLF2 CAES News
Spotting trouble: How Georgians can help combat spotted lanternfly 12/24/24 Emily Cabrera
Native to several Asian countries, the spotted lanternfly (Lycorma delicatula) was first detected in the United States in 2014 in Pennsylvania, likely arriving via imported goods. Since its arrival, the pest has spread to 15 states in the Eastern U.S., now including Georgia. While they do not bite or sting humans or animals, University of Georgia experts stress that early detection, prevention strategies and timely interventions are crucial to minimizing the spread and impact of this pest on a variety of plants.
Top research stories of 2024 CAES News
Top UGA research stories of 2024 12/23/24 Olivia Randall
As the new year approaches, it’s time to reflect on 2024, a year full of exciting research achievements at the University of Georgia. UGA researchers have made their marks examining crucial topics like the health of water resources and urban infrastructure in the face of climate change, the causes of higher suicide rates among young Black men, and an alarming trend in rates of Type 2 diabetes, among other groundbreaking work. Let’s take a closer look at 12 of the most impactful stories of the past year.
After a hearty climb, Connect Abroad Italy students pose in front of the Leaning Tower of Pisa. (Photo by Angel Bhardwaj) CAES News
UGA ranks as leading doctoral institution for study abroad 12/20/24 Angel Bhardwaj
The University of Georgia remains among the top 10 U.S. universities for study abroad participation, according to the 2024 Open Doors Report released by the Institute of International Education in partnership with the U.S. Department of State. UGA boasts the highest study abroad participation to enrollment ratio of the top 7 ranked doctoral institutions, earning the No. 7 spot in overall participation and No. 3 in short-term study abroad programs.
HurricaneHeleneGreenhouseDamageCropped CAES News
UGA Extension supports resilience in Georgia farm communities after Hurricane Helene 12/19/24 Emily Cabrera
Hurricane Helene wrought sweeping devastation across Georgia’s agricultural sector in late September, leaving an indelible mark on both the land and the people who tend it, bringing focus to vulnerabilities in Georgia’s farming industry and the need for more robust safety nets. In addition to the physical destruction, the hurricane took an emotional toll on Georgia’s farmers. In response, UGA Extension has prioritized mental health support.
From left, CAES Associate Professor Abigail Borron and Fulbright Romanian-American Foundation Scholars Mihai Suteu, Daniyar Memedemin, Alina Zaharia, Andreea Ona and Daniel Chiciudean stand in front of an image of the Romanian flag projected onto a barn at UGArden. CAES News
Fulbright Scholars unite with UGA Extension to envision ag outreach model in Romania 12/18/24 Maria M. Lameiras
Arriving on the Athens campus of the University of Georgia in August 2023, five Romanian scholars experienced the same anticipation, excitement and apprehension as many first-year students.  Chosen as Fulbright Romanian-American Foundation Scholars, each serves on the faculty at one of three Romanian universities, specializing in fields from economics and engineering to plant breeding and biotechnology. The five scholars comprised the first cohort of the Romanian Extension Education Development Program, an ambitious three-year pilot effort to facilitate planning and implementation of extension services in Romania. 
Janiver in sunflower field AI web CAES News
A larger-than-life legacy: CAES student’s contagious enthusiasm inspired others 12/17/24 Jordan Powers
When Miriam Edelkind-Vealey applied for a summer role at a University of Georgia pollinator biodiversity lab in 2020, the junior undergrad didn’t quite know what to expect. After being told she got the position, Edelkind-Vealy didn’t hear anything for a few weeks. It was only then that she learned a collaborator on the project, second-year master’s degree student Amy Joy Janvier, had passed away.