This is
generally the time of year we notice sandspur problems in our pastures and
hayfields. Maybe they were there last year too and they're still a problem.
Sandspur can be aggravating for us to control and even more aggravating to a
grazing animal.
Sandspur is
an annual grass weed and tends to grow well in fairly sandy soils. It must drop
viable seed to reproduce. There is more than one type of sandspur – Southern,
longspine and field sandspur can be found in our part of the country. Sandspur
can tolerate poor conditions and is easy to spread via grazing or haying. At
the early stages, sandspur can be a challenge to identify against other
grasses. There are a few characteristics that can help you with identification
early in its growth cycle. Sandspur has a fibrous root system and plants tend
to be a lighter green than many other grasses.
Sandspur seedling (Photo courtesy Virginia Tech). |
The leaves
have several identifying characteristics. First, leaves tend to feel rough,
compared to grasses such as ryegrass. Next, leaves appear flat but are folded
when budding. Third, leaves usually have a raised midvein and have few or no
hairs. The ligule is an outgrowth from the base of the grass blade and is very
important in identification. Here's a photo of a ligule on a sandspur, which is
only a fringe of hairs. Ligules on other grasses may be a thin membrane or may
be non-existent.
Sandspur ligule is a fringe of fine hair, about 1 mm long. Photo courtesy Virginia Tech. |
Sandspur stems can stand straight or spread, splaying
outward. When you run your thumb over the stem it will feel flat, not well
rounded like many other grasses. There can be many branches off the stem as
well, particularly as the plant matures.
Another identifying characteristic for grasses is the
presence or size of auricles. Auricles are projections at the joint
of the leaf blade and sheath. Auricles are absent on sandspur.
Diagram explaining parts of the plant for identification purposes. Diagram courtesy University of Georgia. |
The sandspur’s tell-tale burs are a common sight once the
plant is maturing.
Sandspur producing seedheads or burs. Photo courtesy Virginia Tech. |
Once you know you have sandspur, how do you control it?
First, contact your local Extension Agent for herbicide options. They can give
you information on rates, restrictions, and check products that will work at
different plant growth stages. Second, avoid grazing the area that is infected
to avoid injury to horses and livestock but to also avoid moving seed to a
clean area. Third, when mowing, mow clean areas first before moving to infected
areas. Clean equipment after mowing infected areas. Mowing can give temporary
control to reduce potential for seedhead development but as plants are mown
they typically produce seedheads closer to the ground to compensate. Controlling
sandspur may take more than one season to accomplish particularly if seeds have
banked in the soil and sandspur has been established for years. With multiple
approaches to this weed, sandspur can be controlled.