Glenn Hardebeck, Turfgrass
Research Agronomist, Agronomy Department
Crabgrass is often overlooked or misidentified
until it matures to the point of forming seed heads and stolons,
which begin creeping across the lawn. By this time it may be well into the summer
and the crabgrass plant is nearing the end of its lifecycle. Crabgrass
is an annual warmseason grass. It grows from seed each year,
thrives during hot summer weather when our desirable grasses are
having difficulties, turns purple during cool fall nights and finally
dies with the onset of frosts in the fall. Each crabgrass
plant has the potential of producing upwards of 10,000 seeds, which
can lay dormant in the soil for many years. Therefore, once
a lawn develops a crabgrass problem, preemergent crabgrass control
should be considered thereafter.
Preemergent crabgrass applications have to
be made before the seed germinates. Crabgrass generally germinates early April
in southern Indian to late April in northern Indiana. With
the uncertainty of Mother Nature it is better to apply early rather
than late. A late application will miss early germinating
crabgrass seeds while an early spring application can control crabgrass
well. Although the herbicide is broken down by soil microbes,
the microbes are inactive due to cool soil temperatures allowing
the herbicide to remain in the soil until well after the soil warms
So if you’re planning on applying crabgrass preventer this
spring don’t procrastinate any longer.
Photos courtesy of Dan
Weisenberger, Turfgrass Research Agronomist, Agronomy
Click image to enlarge
Young crabgrass plants are easy to miss. It’s important
to apply crabgrass preventers before the seeds germinate.
Growing crabgrass plants appear light green with a wide leaf blade
during mid May into June.
Mature crabgrass plants are aggressive during the summer heat forming
seedheads and stolons, which creep through the lawn rooting down
and continuing to grow and spread along the way.