For your New Year's resolution this year, if you plan to use herbicides in 2010, resolve to be careful. Too often people apply weed killers and accidentally damage or kill desirable plants. This usually results from not reading the entire label carefully and not identifying the weed to be killed.
How does plant damage occur? Often people spray when windy and the spray drifts from the site of application to desirable plants. Sometimes people apply chemicals when it's too hot and gases form, floating up off of the target plants to nearby plants. Soil-applied herbicides, such as soil sterilants, may have a long residual in the soil, damaging or killing plants whose roots extend into the area.
Once you have identified the weed, the label is the most important tool to the applicator. All the information for successful and safe weed control is on the label. Since the herbicide applicator is legally responsible for following the label, he/she can be held liable for damage that results from misuse. Rule number one is to be sure to read the label before purchasing a product and then again before applying. Then, follow the label. Rule number two is to apply the correct amount of product, at the right temperature (below 85 degrees F) when it isn't windy. This may require spraying at dawn. Rule number three, is do not use weed killer and fertilizer combination products in lawns. They may move through roots into trees, shrubs and flowers damaging or killing non-target plants. Roots of mature trees can extend out from the trunk of the tree four to five times the height of the tree; so although the tree may be what appears to be a safe distance from the lawn, its roots may not be.
Be aware that dormant buds can absorb herbicides in sufficient amounts to result in distorted buds. Also note that spraying suckers of trees with herbicides can damage and sometimes kill the parent plant. Additionally, on sandy soils herbicides move readily through the soil especially after rain or irrigation. I have seen soil sterilants used on a parking pad of a home on a hill above another house. When the rains came, the chemical washed down the hill and killed the neighbor's lawn and trees.
One constant in gardening is the need to manage weeds. Sometimes the safest way is to weed by hand or hoe. If you choose to apply herbicides, read and follow the label.
JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension and may be reached at 887-2252 or skellyj@unce.unr.edu
