Weed control can be simple. If you want to kill everything, use glyphosate (Round-up). If you want to kill broadleaf weeds but leave the grass, use a selective herbicide like 2,4-D. Most of our landscape weed control will fall into one of these two scenarios. This works fine until you have weeds that doesn’t play by the normal rules. Here are three common weed control situations that will benefit from specific technology.
Canada thistle in your lawn
Canada thistle (Cirsium arvense) is an aggressive perennial weed that spreads via roots. It is challenging to control, in part because it has a large underground root system that allows it to store resources and re-sprout after control efforts. In a non-landscape setting, the chemical aminopyralid (Milestone and Opensight herbicides) are excellent tools. Unfortunately, using them on turf is not an option due to label restrictions. You can damage Canada thistle with 2,4-D but there are a three other herbicide options that are better. The easiest of the three to acquire is dicamba. While more effective than 2,4-D it will still require multiple applications to obtain acceptable results. Triclopyr is a better solution. It is typically found in products containing other herbicides. Some of these are Hi-Yield Triclopyr Ester and Turlon. A third herbicide that offers the best Canada thistle control in turf is clopyralid. There are two formulations (that I’m aware of) that allow treatment to turf, Lontrel (clopyralid) and Confront (triclopyr + clopyralid).
Field bindweed in your lawn
Field bindweed (Convolvulus arvensis) is another rhizomatous (spreading via roots) perennial. There is no chemical available that will provide total one-shot control. Once again, 2,4-D in various combinations with dicamba, MCCP, and MCPA will provide some control. If these formulations have left your control lacking, try a product with quinclorac. Bindweed is particularly sensitive to this chemical. Q-4 is an herbicide containing quinclorac that is labeled for lawns.
Grass in perennial flowers and shrubs
Selective weed control is most often thought of as taking a broadleaf weed out of a desirable grass (think 2,4-D). However, there are also herbicides designed to do just the opposite. Sethoxydim will take grassy weeds out of desirable broadleaf plants. Over The Top Grass Killer, Poast, Monterey Grass Getter, Bonide Grass Beater, and Segment are sethoxydim-containing herbicides. There are also certain situations where sethoxydim can be used in fruit and vegetables.
The technology discussed here can make your landscape easier to enjoy. Be sure to consult and follow label directions on the products you choose. The tools are only good if you know how to use them. Following label directions will keep you following the law and prevent undesirable mishaps.