What's bugging you? Sept. 7, 2016
By Jim Leser
Published Thursday, September 8, 2016 8:38 am
The one thing we can all agree on is that weeds are the bane of every gardener. I promised in an earlier column that I would do a series on weeds, notably the 10 most unwanted weeds. This column will act as an introduction and then we will get back to business, one weed at a time in future columns.
There are some terms we need to get a handle on before we start. The first has to do with how a weed grows. There are annuals that return each year from seed they produced the previous years. Keep in mind that some seed can remain viable for years, even decades. So it is imperative that we control these weeds before they produce seed. An example of this type of weed would be the puncturevine, also called goathead.
Then there are the perennials that come back each year without having to rely on seed for their survival. An example of this weed would be hoary cress or whitetop. Perennials do produce seed that can contribute to your misery in following years.
And then there are the biennials. These plants take two years to produce seed. An example of this weed would be common mallow. Finally, there are the weeds that are considered both an annual and a perennial. Black medic would be one of these weeds.
Next in terminology are the kinds of herbicides available for use. First there are the preemergence herbicides. These kill germinating seeds before they can become an above ground weed. These are most effective against annual weeds.
Next there are the post emergence herbicides that kill plants once they are growing above ground. Some are selective such as 2,4-D used for many broadleaf weeds, and nonselective, such as glysophate (Roundup®), which pretty much kill most plants that are green. Not good for weed control in lawns.
And finally there are the soil herbicides that sterilize the soil for a certain amount of time, sometimes as long as 10 or more years. Steer clear of these. There are also chemicals that have soil activity that can be taken in by plant roots. These could harm your ornamentals and are frequently added to other contact herbicides for greater activity. An example of these would be Banvel® or dicamba.
One last issue is that weed control in lawns can be quite different than in and around ornamentals. The herbicides can change as well. I'll try to provide both approaches. Cultural control methods will also be provided.
I have chosen 10 weeds that I particularly don't like in my home landscape. Many more could be added or subtracted, depending upon your situation. These include field bindweed, whitetop, common purslane, cheat grass, puncturevine, dandelion, black medic, redstem filaree, henbit and prostrate spurge. Until next time, happy weed hoeing.
Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University v in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.