How to control foxtails in fields

giant foxtail
As the demand for high-quality hay has steadily increased, hay farmers have seen their product rejected due to foxtails. (Submitted photo)

Is this weedy grass taking over your hayfield?  Have you ever had hay bales rejected from a potential buyer because it contained green, yellow, or giant foxtail?  

As the demand for high-quality hay has steadily increased, hay farmers have seen their product rejected due to foxtails, especially with horse clientele.  

Why is this happening? Well, it has to do with the plant’s anatomy, not a toxin found within the plant.  

Danger to horses

The part of the plant causing problems is the seedhead. Each individual seed contains spikes with barbs called “awns,” which can get lodged inside a horse’s mouth and gums (also scratch an eye), working their way through the tissue, causing lesions, blisters and infections.  

For this reason, it is not recommended to feed foxtail with seedheads to horses. Horse owners have been very careful when purchasing hay, avoiding bales contaminated with green, yellow and giant foxtails. It is important to note that immature foxtail plants have no ill effect since the seedhead has yet to develop.

Over the past few years, I’ve been working with local farmers to control green, yellow and giant foxtails in their hayfield. I typically don’t start working with hay producers until after their hay has been rejected or declined by customers; some are even repeat customers they have known over the years.  

By the time I get involved and make a farm visit, a producer’s fields are usually polluted with foxtails. 

The information and recommendation I give for controlling this weed is expensive and time-consuming — resulting in frustrated farmers.  They are not frustrated at me, but rather the plant and sometimes themselves for letting it take over.  

So, what can be done to control foxtails?  Since this plant is a grass, it can be difficult to control. Depending on the size of the infestation, two of the best options for controlling foxtails are applying a pre-emergent herbicide or pasture renovation (reseeding).


In 2017, Prowl H2O (active ingredient pendimethalin) was registered for use on established pastures and hayfields. Previously, it was labeled for dormant bermudagrass only, but after the change in labeling, it now can be used on cool-season forage grasses grown for forage, silage, hay production, and grazing pastures.  

Since green, yellow and giant foxtails are summer annuals, you must apply Prowl H2O in the spring, before the foxtail seedlings emerge, so it can prevent them from growing. Prowl is also effective on other summer annual grasses like crabgrass and certain broadleaf weeds.

As a producer, you must be aware that this approach has some disadvantages. First, it is somewhat expensive and multiple applications are needed to achieve maximum control.  

Second, this active ingredient has a planting restriction of 10 months for grasses. Therefore, fields with large infestations will have exposed soil with no way to fill it in with desirable grass until the following spring. This gives weeds an opportunity to take over these areas. Also, exposed soil is at a higher risk for erosion.  

One strategy is to overseed the pasture in the fall (now) and apply the per-emergent herbicide the follow the spring.

Pasture reseeding/renovating

If your fields have foxtail large widespread infestations, it may require complete pasture renovation.  Right now, August to early September is a great time to plant cool-season grass seed.  

Although moisture is an issue in late summer seedings, weed pressure is less competitive.  

If you want foxtail to be replaced by a strong healthy stand of competitive grass or grass/clover mixture, it is recommended to do the following: soil test, add appropriate lime and fertilizer amounts, make herbicide treatments to kill existing plants, work the ground to prepare a seedbed includes plowing to bury foxtail seeds), reseed desirable species, proper grazing management (no grazing for at least 6 months), and monitor for success.


Remember, ridding your fields of foxtail may be difficult and can take several years.  The best approach is to be proactive and scout your fields for foxtails to catch invading plants early, whereas a simple spot spray treatment will hopefully control the situation before it gets out of control!


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