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Rock and Roll Agronomy Good Weed Control Like Making Good Deer Sausage By Jason Hanson
We haven’t gotten that many new herbicide chemistries the last few years, what changes there are have mostly to do with what’s allowed on the label or what company owns the label. For the most part, the discussions I have with growers about herbicide products start with economics and end with economics. Performance and expectations show up in the middle of the conversation with the “devil-in-the-details” portion hitting on tank mixes, timings, rates and crop/weed stages. But there is a fundamental factor that drives the answers to those initial questions, and it is something that I have found that people need to spend more time on: weed identification and weed staging. Most growers know what the kochia plant looks like at very small stages and the same could be said for wild mustard. But can you tell the difference between redroot pigweed and waterhemp? How about marshelder, common ragweed and biennial wormwood? These are some tough ones to distinguish sometimes, and communicating the weed in question can get even more complicated when someone gives you the common name that they have always called it. I have heard marshelder called kingweed, ragweed and giant pigweed after the fact when the weed is sticking up above the sunflowers. Even though we have products that will generally cover up mistaken weed identification errors, for the most part the weed needs to be noted and recorded for next year if you are planning dry beans, sunflowers or other non-Roundup Ready crops. There are many good web sites that have weed identification and your local dealers have books like the Nebraska Weed Guide or Weeds of Canada and Northern United States. If you think that you have just green foxtail in the field and then mix a rate of Everest for that weed when you actually have yellow foxtail, it is not the product or the rep’s fault when performance is less than expected. If you don’t have the expertise for this, or the time, some of the best crop production money spent is to employ a good crop scout or consultant. The next thing to do is to make sure that you understand the product you are going to use and the timing for that product. Banvel was and still is one product you should always know what crops it can safely go on and the stage of the crop. Don’t go out onto barley with Banvel at all, and stay off wheat past the five-leaf stage. If you are unsure as to the stage of the crop, make the switch to something like Bison or Starane, products that are safer on the crop. Weed size is also critical to herbicide performance. Rates of herbicides are designed to do a good job on the targeted weeds, as the label will state. The label is the law, and it’s also your bible to safe, effective weed control for that particular product. Some labels will give you a weed height scale such as “Aim controls small weeds (1-2 inches) like nightshade, pigweed, lambsquarter” and other labels give you weed and crop leaf stages. The grass control products almost always give you the weed and crop stage range for control, such as the Discover label saying “apply to wheat from 2 leaf to emergence of the 4th tiller. Discover will control foxtail in the 1-to-5 leaf stage and wild oat in the 1-to-6 leaf stage.” That is pretty specific for a product when you have to realize that not all weeds emerge at the same time, and weather can cause some issues with herbicide uptake. I get many calls on the use of reduced rates, and when they might be used. Cutting rates is fine as long as you have complete confidence in your ability to deliver that mix at the best stage of weed with a reduced rate mix. Very small to small weeds are the best fit for reduced rates to work. Don’t expect miracles out of a tank mix with two broadleaf killers that are both at reduced rates to equal a full labeled rate compound—uh-uh. It doesn’t usually work that way. But if your weeds are small, and you have the “right” weeds out there to knock down, a reduced rate can work very well. Again, weather plays a big part in that equation. Always make sure that you don’t get into tank mixes that increase your antagonism with certain crop protection products. Express is a good broadleaf product but can really reduce wild oat control with some wild oat products. You have to make the call if it’s Canada thistle or wild oats that are the biggest economic obstacle. Pay particular attention if you want to mix in a fungicide with your herbicide application, as some labels are restrictive. Insecticides can also cause increased crop injury with certain formulations and particular products. Don’t be the talk of the town if you sprayed out a hot tank on some great looking crop. Again, good can’t-miss weed control is like making good, time-honored deer sausage. There’s no magic formula, it’s merely experience coupled with following the guidelines of a recipe. Read the label and watch the weather. Pay attention to your crop and weed stage throughout the season, and manage accordingly. Communicate with your dealer or crop consultant. Good luck with managing your fields this summer—and if you have one of those legendary sausage recipes to try next fall, be sure to drop me a note. Hanson is a certified crop advisor, near Devils Lake, N.D. ------------------------------------------------------------------ Weed Control Sources on the Web: North Dakota State University www.ag.ndsu.nodak.edu/cropprod.htm University of Minnesota http://appliedweeds.coafes.umn.edu/ South Dakota State University http://plantsci.sdstate.edu/weeds/ Montana State University www.montana.edu/wwwpb/pubs/index.html#Weeds |
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This time of year is my favorite because we get to put
the hurt on weeds out in our fields. To do so successfully, one must master getting the timing right with not spending too much to get the job done. This balancing act might be similar to each passing winter
when we sample different deer sausage recipes: it’s the competition amongst deer hunters to combine the art of the hunt with the master of the kettle. I know, comparing weed control with making deer sausage is
a stretch. But if you are consistently skilled at both, you earn peer admiration and legendary status that can last for years.