Select and use herbicides without harming the environment

Fifteen steps to safely apply herbicides.

Herbicides are a necessary tool that many farms utilize for pest control. The challenge that farms face in using these chemicals is the effect they may have on the environment. Michigan State University Extension recommends that farms consider the following steps when choosing and applying herbicides:

  • Select herbicides carefully. Remember, herbicides that are highly soluble, relatively stable and not readily adsorbed to soil tend to be the most likely to leach. Choose herbicides with the least potential for leaching into groundwater or for runoff into surface water. Read labels carefully and consult a specialist from a MSU Extension office or your pesticide dealer, if necessary.
  • Herbicides containing atrazine may not be mixed or loaded within 50 feet of perennial or intermittent streams, rivers, lakes or reservoirs. These herbicides cannot be applied within 66 feet of the points where field surface water runoff enters perennial or intermittent streams and rivers or within 200 feet of lakes or reservoirs. These herbicides can be applied to HEL (highly erodible land) acres only if the 66-foot buffer or setback from runoff points is planted to a crop or seeded with grass.
  • Herbicides with Label Advisory Statements. Refer to the herbicide label for advisory statements regarding groundwater and surface water protection requirements. All applications must be made in compliance with labeled instructions.
  • Follow label directions. The label carries crucial information about the proper rate, timing and placement of the herbicide.
  • Reduce herbicide application rates. Use the lowest rate of the herbicide that provides adequate weed control. Band applications of preemergence herbicides reduce the potential of herbicides to leach or run off by 50 percent or more.
  • Incorporate pesticides. On fields not considered highly erodible, incorporation of pesticides can be used to reduce runoff by moving some of the pesticide below the soil surface away from overland water flow. Incorporation of herbicides will not be compatible with surface residue requirements in some fields.
  • Calibrate accurately. Equipment should be calibrated carefully and often. During calibration, check the equipment for leaks and malfunctions. Contact your local MSU Extension educator for assistance.
  • Measure accurately. Concentrates need to be carefully measured before they are placed into the spray tank. Do not “add a little extra” to ensure the herbicide will do a better job. Such practices only increase the likelihood of injury to the treated crop, the cost of pest control, and the chance of groundwater and surface water contamination.
  • Avoid back-siphoning. The end of the fill hose should remain above the water level in the spray tank at all times to prevent back-siphoning of chemicals into the water supply. Use an anti-backflow device when siphoning water directly from a well, pond or stream. These practices also reduce the likelihood of the hose becoming contaminated with herbicides.
  • Consider weather and irrigation. If you suspect heavy or sustained rain, delay applying herbicides. Control the quantity of irrigation to minimize the potential for herbicide leaching and runoff.
  • Avoid spray drift and volatilization. Preemergence herbicide applications have the greatest potential for volatilization and runoff.
  • Clean up spills. Try to avoid spills in the first place. When they do occur, control, contain and clean them up quickly with an absorbent material such as cat litter. Chemicals spilled near wells and sinkholes can move directly and rapidly into groundwater. Chemicals spilled near ditches, streams or lakes can move rapidly into surface water.
  • Change the location of mixing areas. Mix and load pesticides on an impervious pad, if possible. If mixing is done in the field, change the location of the mixing area regularly. Do not mix herbicides adjacent to the water source and do not let the water run inadvertently on the soil near the mixing area. This will increase herbicide leaching and/or runoff.
  • Dispose of wastes properly. All herbicide wastes must be disposed of in accordance with local, state and federal laws. Triple-rinse containers. Pour the rinsate into the spray tank for use in treating the site or the crop. Do not pour rinsate on the soil, particularly repeatedly in the same location. This will saturate the soil and increase the potential for herbicide leaching.
  • Store herbicides away from water sources. Herbicide storage facilities should be situated away from wells, cisterns, springs and other water sources. Michigan’s water resources currently provide a vast supply of clean water for agriculture, homes and industry. They can ensure high water quality for future needs only if they are protected now. Be sure to understand how your activities, including herbicide usage, can affect them.

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