Hard to Kill!

There are several hard to kill weeds that can be found in many lawns in our region. We seem to have more problems with these “resistant” weeds in our area compared to the larger urban areas to the south, probably due to the source of our soil, often farmland.

Weeds are classified in three ways according to their susceptibility to various weed control products.

First are the “susceptible” weeds. These weeds are relatively easy to kill with the sprays, dying fairly quickly after proper application of a weed control product. Susceptible weeds include dandelion, ragweed, chickweed, plantain, and about 50 other common broadleaf weeds.

Second are the “intermediate” class of weeds. These weeds are harder to kill with the weed control spray and it may take several applications over the course of a season or a few years to get them under control. You may never eradicate them entirely. Weeds in this category are mallow, purslane, black medic, ground ivy (also known as creeping charlie), and thyme-leaved speedwell. Sometimes repeated applications fairly close together can help eradicate these weeds.

The third class of weeds are the “resistant” weeds. In our area, the most prevalent resistant weeds are creeping bellflower and wild violet. Buttercup, Japanese knotweed, and goutweed are also resistant but not very common in our area. We have tried repeated applications on some of these resistant weeds in the past to try to control them. Sometimes the spray will have effect, and other times there is little or no effect.

Unfortunately, if you have intermediate or resistant weeds in your lawn, digging them out may be the only solution. Then top-dressing & over-seeding may be required. You can use a vegetation killer like “Round-Up” on these hard to kill weeds. Yet remember, you’ll kill the grass as well when you use a vegetation kill, so use it as sparingly as possible.

 With the exception of bentgrass (used on golf greens), most grass types are resistant to the weed control product. This is why we can spray an entire lawn but not injure the grass!