Posted by: Dennis Hinkamp on Sep 19, 2012
Safe Pesticide application
|USU Extension horticulturist|
|USU Extension writer|
Ask a Specialist: The Basics of Pesticide Application
LOGAN, UT – This time of year, many gardeners are frustrated with the weeds that plague their yards, and they resort to lawn weed killers such as Weed-Be-Gone and Trimec. While these are useful in getting rid of weeds and are convenient to use, it is important to use them with caution. There are many examples of costly damage occurring because of herbicide misapplication. When this happens, those whose misapply can be held legally responsible, and associated fees can be a surprising consequence.
One way to avoid having to use an herbicide is to maintain a healthy lawn. When lawns are mowed at the proper height, watered so roots can penetrate deeply into the soil and otherwise properly maintained, weed problems are minimized. Consider these tips.
• Lawn weed killer is best considered a temporary tool when applied in combination with other methods to make the turf more resistant to weed growth. Be sure to read the label before purchasing and applying. Labels can sometimes be difficult to follow, but they contain all the necessary information to avoid accidents. Manufacturers spend millions of dollars to ensure this. One example of a limitation listed on lawn weed killer labels is that they must not be sprayed at temperatures above 85 to 90 F. This is because the active ingredients in them will volatilize and drift in the wind, potentially for hundreds of yards, and possibly damage any desirable plants they contact.
• It is not recommended that homeowners spray lawn weed killers during the hottest summer months. If it becomes necessary to use them, apply after sunset and then only spot spray the worst areas, not the entire yard.
• The optimum time of year to apply lawn weed killers, in most instances, is in the autumn when plants are still actively growing and temperatures are cooler. In fact, biannual and perennial weeds are drawing sugars and other nutrients from their leaves to their roots for winter storage. If an herbicide is applied at this time, it will also be stored in the roots over the winter and increase the likelihood that the sprayed weeds will be killed. This is especially true for field bindweed (morning glory) and dandelions. Another time of year to consider spraying is when plants start actively growing in the spring while temperatures are still moderate.
Direct column topics to: Julene Reese, Utah State University Extension writer, Logan, Utah, 84322-4900; 435-797-0810; firstname.lastname@example.org.