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Proper management increases weed control success

By Eddie Funderburg, Ed.D.
Senior Soils and Crops Consultant

Posted Apr. 1, 2015

Many factors must be considered to implement a weed control program for summer pastures. This article deals with the basics that must be done for your weed control program to be successful.

First, scout your pastures to see if you have enough weeds to justify spraying. Sometimes, the inclination is to spray without looking to see if you should. A well-managed and properly stocked pasture should not need herbicides every year. A little time spent scouting may save you a lot of unnecessary time and money on spraying when your weed population is not high enough to justify it.

If you have enough weeds to spray, identify the species present. Correct weed identification is essential to select an herbicide that will control your weed spectrum. Incorrect weed identification can lead to two types of errors. You may choose an expensive herbicide when a less expensive one would have done the job, or you may choose an herbicide that does not adequately control the weeds you have, regardless of its cost. Refer to plant identification sites on the Internet and reference books, or take the plants to someone you trust to help you with identification.

Once you have identified the weed species in your fields, get prices on pasture herbicides sold in your area and check their labels for the weeds they will control. Herbicide labels are attached to their containers or can be found on different sites on the Internet such as agrian.com or www.cdms.net. Match this information with the price per acre to determine the best and most economical herbicide to fit your weed spectrum. Time spent examining your herbicide options can either save you money or save you from having a weed control failure.

When you have decided on a herbicide, scout the fields again to make sure the weeds are in the correct growth stage to achieve good control. Most weeds should be sprayed when they are small and actively growing, but there are exceptions to this. The label will usually show the weed height or growth stage that is optimum for control.

Before you spray, calibrate your sprayer. This is an essential step that many farmers and ranchers omit. There is no way to know how much herbicide to put into the tank if you do not know the output of the sprayer. Sprayer calibration is not difficult and does not take a lot of time. The Noble Research Institute has calibration guidelines for boomless sprayers and for sprayers with booms.

The Noble Research Institute also has online calculators to aid in calibrating boomless sprayers and boom sprayers.

Read the label carefully to determine if additives are required for the herbicide to work at an optimum level. A nonionic surfactant is usually required, but some herbicides may require a different adjuvant. Also, some herbicides contain surfactant and no more is needed. The only way to know is to read the label.

After you have done all the things listed above, make sure the correct environmental conditions are present before you spray. The major environmental considerations are wind speed and direction. If the wind speed is too high, the herbicide will not be properly deposited on the weeds. If the wind is from the wrong direction and your spray drifts onto sensitive plants belonging to a neighbor, you may be in legal difficulty.

Keep accurate records of your spray activities. Learn and follow the rules and regulations that pertain to your state.

Implement these simple rules when you plan your pasture weed control program and your chances of success should be good. Ignore these rules and your chances of success are much lower.

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