Nutsedge: The Superweed
The best way to describe nutsedge is “superweed.” Unlike other broadleaf weeds, this sedge has a robust root system made of nut-like tubers called nutlets. The nutlet stores a high amount of energy for the nutsedge to use in its lifecycle. With their grass-like leaves, sedges can be difficult to distinguish within the lawn at the beginning of the growing season. In the hot, humid, sunny days of summer, however, it grows faster than most grasses and even begins to flower. It is easy to distinguish only a few days after mowing by the lighter green leaves shooting up quicker and taller than the grass surrounding it.
The best way to control crabgrass is to kill it before it grows with a pre-emergent herbicide, but when is it too late to treat? Unfortunately, there’s no single definitive answer to this question. The short answer is to apply it before the crabgrass has a chance to germinate. The longer answer is that it depends on the weather and which pre-emergent is being used. Pre-emergent herbicides work by creating a chemical barrier that kills the crabgrass when it germinates. Some pre-emergent products provide some post-emergent control as well. Determining when a seed germinates depends on many variables in the environment. For crabgrass, the biggest variable is temperature. Crabgrass only germinates at sustained soil temperatures above 57°F at a one-inch depth. The best way to track the soil temperature is with growing degree days (GDD). Because it is tough to track soil temperatures without specialized equipment, we can use air temperature. Air temperatures will usually need to be at around 50°F for 200 degree days for germination. (more…)
Often, clients will call concerned with what they perceive as weeds in their lawn. Our regular applications control most of the weeds in your lawn, but there are a few that require special applications. This publication from the Home and Garden Center Information Center of University of Maryland Extension explains the basics of lawn weed biology and how they are controlled. There are two exceptions to the article that I would like to make you aware of. (more…)