By Lonnie Jenschke
Erath County Extension Agent – Ag/NR
According to James Jackson, Extension program specialist, the past few years forage producers around central Texas have been blessed with late winter and early spring rains. While no forage producer complains about rain, these rains often bring about many cool season annual grasses that can cause problems for forage production, especially early season hay cuttings.
Problems that we commonly see are reduced hay quality and quantity at the first cutting and, in cases when it stays cool and damp, this could persist into the summer.
For years, the control method of choice for annual cool season grasses has been to apply glyphosate (Roundup) during the coastal dormant season, typically in the months of February or early March after cold weather has ensured all warm season desirable grasses are dormant. However, in recent years we have also see an increase in glyphosate resistance among cool season grasses. This forces many producers to consider other options for control of cool season annual grassy weeds.
When glyphosate resistance is present, other control options that can be utilized for annual grassy weed control are the use pre-emergent herbicides. However, a challenge of this is realizing that you have a problem prior to having the problem. While it is too late to use this option this year this is an excellent time to see if you have a problem and make plans for next year.
If a problem is an annual occurrence, you could apply a pre-emergent herbicide in October, or make plans to target the field with glyphosate in February or March depending on the species of annual grassy weeds present.
Cool season annual grassy weeds that we commonly fight are ryegrass, rescue grass, six weeks fescue, little barley and Japanese brome.
Annual Ryegrass-Introduced is easily recognized by its alternating seed head. This grass can offer desirable cool season grazing. However, over time, it can decrease quality of hay as well as thinning out desirable perennial grass. Due to the glyphosate resistance of this grass, it is necessary to apply a pre-emergent herbicide in the fall to control it.
Rescue grass-Introduced is common in both yards and improved pastures. Currently no known cases exist of glyphosate resistance. It can be controlled by glyphosate application or by pre-emergent herbicides applied in the fall.
Little Barley-Common is a native annual cool season grass that is commonly seen in improved pastures. Currently it can be controlled by glyphosate applications in February or March.
Six-Weeks Fescue is a very fine wiry stem grass that has increased in abundance the past few years. There have also been reports of glyphosate resistance with this grass. This requires a fall preemergent application to gain control.
Japanese Brome is easily identified by its hairy base and oat type seed head, this introduced plant is common on roadsides and in improved pastures. Currently, there are no reports of glyphosate resistance and control has been achieved by glyphosate applications in February and March.
Currently the only pre-emergent herbicide labeled for improved pastures is Prowl H20 (active ingredient pendimethalin). However, more should be available for improved pastures soon as Bayer is expected to get Rezlion (active ingredient Indaziflam) labeled for the pasture market.
Lonnie Jenschke is the Erath County Extension Agent – Ag/NR. He can be reached at firstname.lastname@example.org.