Annual Ryegrass is appearing in many
new lawns this spring
Glenn Hardebeck, Turfgrass Research Agronomist, Department
of Agronomy, Purdue University
There have been quite a few samples sent to
the P&PDL this
spring from individuals complaining of a wide bladed, weedy grass “invading
my new lawn”. When there is an undesirable grass mixed
throughout a turf stand, it’s very important to correctly
identify the weedy grass species to determine whether it is an
annual or a perennial. If the problem is a perennial grass,
there are very limited control options available. For most
perennial weedy grasses in cool-season turfgrass stands, non-selective
control of everything or mechanically removing each perennial grassy
weed are the only alternatives. Fortunately most of the “invaders” this
spring on lawns seeded last fall have been annual ryegrass due
to a mild winter.
Annual ryegrass is often found in lower quality
seed mixes. It
was originally thought to be a good “nurse crop” because
of its rapid establishment. Unfortunately, it is very coarse
textured and tends to grow faster than the desirable turf. So,
the wide blades shoot up rather quickly between mowings, adding
to the poor uniformity of the turf stand. All this would
be tolerable, in most circumstances, if annual ryegrass would hold
true to its name and die off rather than persisting in newly seeded
or overseeded lawns.
Harsh winters or hot summers are required to
push annual ryegrass out of the turf stand. Until the weather removes the annual
ryegrass, the turf area may require additional mowing to help reduce
the poor uniformity caused by this quick growing, wide-bladed weed. The
best form of control is to avoid seed mixes containing annual ryegrass.
Click image to enlarge
Annual Ryegrass is coarse textured and normally light green.
Each group of seeds are close to the seed stalk branching alternately.
Annual Ryegrass has clasping auricles. Where the leaf meets
the stem, there are claw-like parts that wrap around to the opposite
side of the stem.