Foxtail in Horse Pastures

One of the biggest problems in horse pastures – and I’m talking about real pastures, not enclosures where horses are kept – is a grass known as Foxtail.  This is an annual grass, and there are several species found in North Carolina.  Foxtail causes problems in horses and other livestock when they try to eat the mature plants.  When mature, Foxtail species have a fuzzy seed head that has long, spiked awns.  These awns stick into the cheeks, lips, and gums of a horse causing lesions, sores, and mouth ulcers.  Horses with sore mouths don’t want to eat, are likely to lose weight, can develop colic, or have other problems.  In short, Foxtail and horses are not a good match.

Until recently, there has not been a herbicide that we could use to manage Foxtail in pastures.  Currently, there is a supplemental label that allows the use of Prowl H₂O on cool season grasses grown for forage or hay production, or in pastures or rangeland.  There may be other formulations of pendimethalin that have a supplemental label, but I’m not aware of them.  This supplemental label expires on April 30, 2019, so the window to use this product in cool season pastures and hay fields is limited.

The supplemental label is for established perennial cool season grasses – those with 6 or more tillers per plant.  Since this is a preemergence herbicide, it should be applied before the foxtail germinates.  For most pastures, the application window is in February or March, just before the Foxtail seeds germinate.  A maximum of 4.2 quarts may be applied during the year.  Since the label will expire next April, perhaps a heavy application will provide good control.  The heavier application rate will provide longer residual protection.  Split applications may also work well, with no more than 2 quarts per acre applied each of the 2 applications.  All applications must be applied before the supplemental label expires at the end of April in 2019.  See the product label and the supplemental label for precautions, mixing instructions, and application instructions.  If assistance is needed in finding these labels, contact your county NC Cooperative Extension office for assistance.

Some restrictions are:

- DO NOT apply if surface water is present in the field.

- DO NOT apply more than a maximum cumulative total of 4.2 quarts per acre per year.

- WAIT 14 days after application to graze or harvest hay after an application of pendimethalin.

- DO NOT apply to mixed cool season grasses and legumes other than alfalfa.  Applications can be made to mixed stands of cool season grasses and alfalfa.

Applying a herbicide is not a magic wand that will end all of the problems with Foxtail.  It will not make up for poor stand management.  Using a herbicide is a tool that we can use to make improvements to pastures and hay fields.  Remember there are other tools that are critical to keeping a viable stand of desirable cool season perennial grasses for horses to graze.  Those tools include keeping soil fertility levels in the optimum range for growth, keeping the soil pH in the 6.2 to 6.5 range, overseeding when necessary, and NOT overgrazing.

Foxtail is an opportunist grass.  It will fill in open areas in the pasture along with undesirable broadleaf weeds. Sunlight directly hitting an open spot in a pasture = a spot where weeds are going to grow since they have the opportunity. Forage managers should work to keep those bare areas of soil in the pasture to a minimum.

If Foxtail is a problem, we now have a really good tool to help get a handle on it.  However, if a herbicide application is not followed by the rest of the steps necessary to reclaim and improve a pasture, the money spent on applying the herbicide will have been wasted.  Go ahead and get the soil tests needed and make any fertilizer and lime applications recommended.  If there are bare spots between the clumps of cool season grasses, overseed in the fall to get the new perennial forages growing.  Follow those actions up with the herbicide application in late winter to help keep the Foxtail seedlings from surviving.  The fall-seeding should go a long way toward filling in the holes and will provide some good grazing for years to come – with continued good forage management!