Growing up on a southern Indiana farm, I learned a lot about weed identification from my Dad. He would point out features of various plants, and by the time I was 12 years old, I could identify many of the more common broadleaf plants. Two weeds I had an easy time identifying were marestail and horseweed. These two weeds are a great concern these days, because both are becoming glyphosate resistant in our region.
When I moved to northern Indiana in the early 80’s, one of the first lessons I learned was that the common name of a weed can depend upon the part of the country you are in. The weed I grew up calling marestail is referred to as horseweed in most of the Midwest. And to make things more confusing, the weed I grew up calling horseweed is commonly known as giant ragweed. Such regional differences in plant names are not uncommon.
Why are plant names important? Pesticide recommendations, whether they come from universities or companies, are based on properly identified plants. In fact, these two weeds are becoming such a huge problem in parts of our state, Purdue and other Land Grant universities have published publications specifically about these hard to control weeds. The recommendations for horseweed are quite a bit different from those for giant ragweed. Using the wrong name could lead to a costly mistake.
Because of these regional differences in the names of plants, some labels will mention other names for a weed. Many labels, for instance, will call my version of “marestail” horseweed, with the word marestail listed in parentheses. I have never seen giant ragweed, however, listed as horseweed.
We have entered a new era. Herbicide resistant crops and weeds are going to be changing the way we deal with weeds. The names of plants are not the only issue. Look-a-likes such as Palmer Amaranth, waterhemp and the pigweeds can be confusing, and without a proper ID, your fields can be taken over in just a year or two.
My favorite weed identification book is the Weeds of the Great Plains, published by the University of Nebraska and the Nebraska Department of Agriculture. It has excellent color pictures of 400 plants at various stages of their development, and great descriptions of the plant parts. If the weed has a look-a-like or a different regional common name, these are often noted in the text.
Best of all, it is inexpensive. This hardbound book is only $25. You can mail your check payable to the Nebraska Department of Agriculture, Central Fee Collection, PO Box 94668, Lincoln, NE 68509. You can also call (402) 471-2394 to use a credit card.
If you are interested in weed control recommendations, I suggest visiting www.extension.purdue.edu/extmedia/WS/WS-16-W.pdf. This link takes you to the 2015 Purdue, Ohio State and Illinois weed control guide. Updated every year, it has much information about hard to control weeds in soybeans, corn, sweet corn, popcorn, small grains, pastures and forages. It’s a huge publication, with more than 200 pages of up to date information, including herbicide resistant plants.