Grassy weeds becoming obvious in dormant
Glenn Hardebeck, Turfgrass Research Agronomist, Department
of Agronomy, Purdue University
As the summer
heat and drought slow the growth of our cool season grasses such
as Kentucky bluegrass, other drought and heat resistant grasses
begin to stand out. Three here include crabgrass,
goosegrass and tall fescue. In most situations, control of
these grasses is better left until this fall or next spring depending
on the species. Crabgrass and goosegrass are annual grasses
that are primarily controlled with preemergent grass herbicides
applied early spring. Tall fescue is a perennial and therefore
can not be removed from a turf stand with a preemergent herbicide. Control
of tall fescue requires multiple applications of a non-selective
herbicide such as Roundup or multiple applications of a selective
herbicide available to professional applicators. Additional
information can be found at http://www.agry.purdue.edu/turf/pubs/AY-10.pdf http://www.agry.purdue.edu/turf/pubs/AY-11.pdf
Click image to enlarge
Green clumps of tall fescue (left) as well as crabgrass and goosegrass
(bottom right) are very conspicuous in this dormant Kentucky bluegrass
Small, round, green stems with swollen joints (nodes) can be seen
at the center of this spreading crabgrass plant. Roots can
form at the nodes allowing crabgrass to spread readily.
Crabgrass seedheads are distinctive from that of goosegrass.
Goosegrass stems develop a white, flattened rosette at the plant’s
Goosegrass seedheads have two flattened rows of seeds on individual
Tall fescue is wider bladed and more drought resistant than Kentucky
bluegrass or perennial ryegrass forming clumps in a mixed stand.
Tall fescue is not likely to have a seedhead at this time of year
and is often red to purple at the base of the stem.