How to select the right herbicide

I spent all of Memorial weekend weeding and only got a portion of my 21⁄2 acres weeded. My gas-powered weed eater was my tool of choice and I worked for hours chopping down unwanted grasses and other undesirables. I also pulled many more out by hand. I'm not against chemicals, but I wanted it to look good that day, not a week or two later.

Speaking of chemical herbicides there are many for sale in nurseries, home improvement centers or even drug stores. Here are a few tips that will help you select the right product, if you choose to apply an herbicide.

First, be aware there are different kinds of weed killers. Some kill almost everything green they touch and are called "non-selective." This includes products that contain glyphosate, such as Round-up or Kleen-up. You have to be really careful not to spray desirable plants or have the chemical drift to plants you want to keep.

Others selectively kill only monocots (grasses, iris, lilies, etc.) or dicots (broadleaf plants, junipers, pines, etc.). Selective herbicides come in handy when you want to kill grasses in a flower bed or dandelions or other broadleaf weeds in a lawn.

The second thing you want to know about herbicides is that they work on the plants listed on the label. You have to know what kind of weed you are trying to kill in order to buy the right product. We can help you identify weeds at University of Nevada Cooperative Extension. Then, read the label.

Third, there are products that are pre-emergent or post-emergent. Pre-emergent products put down a chemical barrier and prevent seeds from emerging from the soil and growing. They do not work on existing weeds. They do not control all weed seeds. Read the label for which ones they will control. Post-emergent products kill existing weeds.

Finally, there are soil sterilants. I rarely recommend these for general homeowner use. Often these move with soil water and runoff. I have often seen significant damage from sterilants that were applied to keep all the weeds out of a specific area drift with water runoff to other areas and kill grass, trees and shrubs. Or, that were applied to keep weeds out of rocks in a planted area, but where desirable plants absorbed the chemical and died.

If you have herbicide questions, call me at 887-2252 or e-mail skellyj@unce.unr.edu

JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension.