Working together to strengthen and support noxious weed management efforts in Montana.


Learn About Calibration for Using Herbicides

Thursday, August 19th, 2010


One of the most important things that can be done when using herbicides is making sure you are spraying the right plant and you are using the right amount of herbicide.  Learning how to use the right amount of herbicide is called calibration.

There are many ways a person can learn about calibration.

  • Contact your local weed coordinator or extension agent.
  • Attend a Private Applicator’s Class in your area.
  • Use a combination of print and video materials available.

The following are some of the print materials available.  We have provided links or you may contact your extension agent.

MWCA helped to underwrite this short video that demonstrates calibration of equipment.  We have broken it down in to 6 steps.

Chapter 1 Importance of Calibration

Chapter 2 Equipment & Pre-Calibration Check

Chapter 3 Understanding Calibration

Chapter 4 Calibrating Backpack Sprayer and Handline

Chapter 5 Calibrating Using the Strip Method

Chapter 6 Adding Pesticide to Your Tank

MSU Extension also has a DVD available for purchase on their website. There is also information on the MSU Webpage on Calibration.

How much chemical do I use for my sprayer?

Friday, October 23rd, 2009


Because soil and environmental conditions vary greatly across Montana, and all sprayers distribute spray at different rates, generic recommendations cannot be made. Please contact your local county weed professionals to obtain the best recommendations for your specific plants and conditions.

What is sprayer calibration and why do I need to calibrate my sprayer?

Friday, October 23rd, 2009


The objective of calibration is the same no matter what kind of sprayer you are using, to apply the correct amount of chemical to do the job.  All pesticide labels tell you how much you should be applying.  If you apply too much chemical you may impact other plants and resources that you do not want to.  If you apply too little chemical you may not get the results you want.

MWCA has a web page with videos and reference materials to help demystify calibration.