New Lawns with Clumpy Perennial Ryegrass
Glenn Hardebeck, Turfgrass Research Agronomist, Department
of Agronomy, Purdue University
New Lawns are often seeded with a mix of perennial
ryegrass, Kentucky bluegrass and fine fescues. Perennial ryegrass is included
for its quick cover, Kentucky bluegrass for its recuperative ability
and fine fescues for shade tolerance. Unfortunately, in many
cases the perennial ryegrass does its part too well. It germinates
very quickly and as a strong seedling, it dominates the turfgrass
stand. Since perennial ryegrass is very disease susceptible
and is a bunch-type grass with little ability to spread into voids,
thin, clumpy lawns can often result.
If you noticed severely thinned turf areas
in your lawn before the recent snowfall, dormant overseeding
with a blend of Kentucky bluegrass cultivars would be an easy
choice to improve the situation. Dormant
overseeding can be accomplished anytime from December through early
March. Mother Nature will “plant” the seed for
you through natural freeze-thaw cycles and it will germinate when
the soil warms next spring. A limitation is that dormant
seeded turf cannot be treated with a crabgrass pre-emergent herbicide
next spring. Instead, a post-emergent product such as Drive
should be used to treat crabgrass after it germinates.
A final note would be to avoid the situation,
if possible, by limiting the perennial ryegrass component of
a seed mix to 10-15%. More
information can be found at
http://www.agry.purdue.edu/turf/pubs/AY-3.pdf
http://www.agry.purdue.edu/turf/pubs/AY-25.pdf
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Click image to enlarge

A severely thinned stand of perennial ryegrass will not spread and
fill in without overseeding. |