One of the most common weeds to come into the extension office at Iowa State this week has been Orchardgrass (Dactylis glomerata). This is a common lawn weed in Iowa. It is a perennial that is used a forage grass and often ends us in lawns. It is best known for its rapid growth, its long membranous ligule, and its distinctly folded vernation. There is no good control for it, other than pulling it or using Roundup on it. None of the selective herbicides work in cool-season lawns, including Tenacity. Tenacity will turn it white, but it recovers. It is a bunch grass and does not spread by plant parts, but it is a good seed producer and the seed often finds its way to lawns from surrounding, unmown areas. It grows several inches above Kentucky bluegrass in the spring and catches the attention of the homeowner in April and May. Even in midsummer, it grows faster than bluegrass.
The very long, membranous ligule is one of the best identifying characteristics.
The inflorescence is quite distinct and shows up in late summer and fall
It grows rapidly, particularly in the spring and stands out in a Kentucky bluegrass lawn.