Sprayer Calibration
Mar 16, 2017 | 908 views | 0 0 comments | 13 13 recommendations | email to a friend | print

When it comes to weed control in pastures and hayfields, it may require several tools in the tool box to be successful.  The best defense against weeds is a good, dense stand of grass or forage.  There are several things to help us be successful in weed control management.

The first thing is to perform a soil test.  Soil fertility is important as soils are the basis of all we do on an agronomical level. Soil is the basis of lawns, gardens, pastures, hayfields and livestock production to name a few.  The soil test will determine nutrient levels present or lacking and how we as a manager can improve these over time.

The second thing is to determine what weed species are present.  Are the weeds annuals, biennials, or perennials?  This is important because not all weeds are equal. Different weeds are controlled at various stages of growth and development.  Annuals are easily controlled in the seedling stage while perennials are controlled in the flower and bloom stage.  Biennials are controlled in the rosette stage.  

Using selective pesticides to control unwanted vegetation in pasture or hayfield may be part of the process.  Many farmers and ranchers today incorporate Integrated Pest Management into their arsenal of weed control.  

A common question many have is how much pesticide do I add to the spray tank?  This is a good question but there are some things we need to know first.  Do you know how much your sprayer puts out?  Calibration of the sprayer can help answer lots of questions for us.

So how do I calibrate my sprayer?  First do you have a boom or boomless sprayer.  For a boom sprayer, determine nozzle spacing.  We have handouts with nozzle spacing and recommended calibration course lengths.  For example, if nozzle spacing is 24 inches then the course would be 170 feet long.  If the nozzle spacing is 32 inches then the course would be 127 feet long.

Measure and stake off the appropriate calibration course based on nozzle spacing.  The course should be on the same type of ground that will be sprayed.  Speed is important so use similar conditions as to be sprayed.  Drive the course in the gear and rpm you will use when spraying.  Record the time in seconds and do this several times on the course to get an average.  Park the tractor and maintain the same rpm.  Turn the sprayer on to catch water from the nozzle for exactly the same number of seconds that it took to drive the course.  For a boom sprayer, ounces caught equal gallons per acre.

For a boomless sprayer, measure the effective swath width.  For example, a 35 foot swath uses a calibration course of 157 feet.  For a swath of 45 feet, use a calibration course of 121 feet.  Follow the same instructions as mentioned above for a boom sprayer by driving the course recording the time in seconds.

Turn on the sprayers and use a bucket that will fit over the cluster nozzle as it is important to catch all water during the amount of seconds you traveled the course.  For a boomless sprayer, pints caught equal gallons per acre.  

Once we determine what our sprayer is putting out at different speeds and terrain, we can then determine how much product to add to the spray tank.  This is important to get effective control and use pesticides in accordance with label instructions and label rates of application.  Under applying or over applying can both be a problem when using pesticides to controlling weeds.

Now if you are not certain what weeds you are dealing with the Extension Office is hosting a Herbicide Update program for weed identification and control March 20th. The program will be held at the Yamboree Exhibit building. Doors open at 5:30 for the meal with the program following. If you would like to attend or get more information contact Shaniqua at 903-843-4019  


Shaniqua Davis is the County Extension Agent for agriculture and natural resources for Upshur County. Her email address is Shaniqua.davis@ag.tamu.edu   

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