Selective vs. Nonselective

• Pesticides fall into two broad groups: selective and nonselective. Selective herbicides target a specific type of plant. Related plants are not harmed. Nonselective herbicides, on the other hand, pose a risk to any plant or animal with which it may come into contact. Best practices dictate that to protect the environment, nonselective herbicides should only be used when you are trying to totally clear an area of weeds, such as when setting up a new lawn. Whenever possible, use a selective herbicide to prevent accidental contamination.
  
  

Application Timing

• There are two factors concerning the timing of herbicide application. First, application should be done when it will be most effective. Generally, the timing of the plant's life cycle will determine when this should occur. Generally, herbicide application is most effective if it is done prior to a weed going into flower. Second, never apply herbicides on a windy day. Wind speeds of less than 10 miles are preferably in order to prevent contamination through drift. Leaving a buffer area around a site may also reduce the possible of drift into nontargeted areas.
  
  

Preventing Runoff

• Agricultural runoff consisting of herbicides, pesticides and fertilizers is the number one source of water pollution, according to the U.S. Environmental Protection Agency (EPA). It is therefore imperative that you take measures to prevent contamination of ground water and surface water when applying herbicides. The landscape often determines the environmental risk, especially in areas with high slopes. Herbicides are rated for their potential for surface water contamination. Read the manufacturer label and the Material Data Safety Sheet (MDSS) for proper application instructions. The label is a legal document that details an herbicide's use. Consult your state agricultural extension office for more information.
  
  

Nontargeted Species

• The label or MDSS will provide information regarding potential environmental risks with using certain herbicides. To avoid injury to bees, avoid spraying in areas with flowering plants. In addition, EPA regulations may prohibit the use of herbicides in areas where there are endangered and threatened species. It is your responsibility to determine whether these species may be impacted. Your state agricultural extension office can advise you.
  
  

Considerations

• Most state regulate the use of certain herbicides, especially those deemed more hazardous. In some cases, a license or permit will be necessary before you may apply some herbicides. Training includes detailed instruction on how to prevent environmental contamination and the safe handling of herbicides. In addition, some herbicides carry cautions regarding the transport and mixing of certain chemicals.