During the growing season, many pastures and hayfields contain an unwanted intruder. At first glance, it looks like the popular Timothy grass, but a closer inspection will tell you that it is really Foxtail.
Foxtail is a summer annual grass, meaning it grows from seed in the spring and dies in the fall. To come back year after year, it drops hundreds and hundreds of seeds into the soil each growing season. A Timothy look alike, it can cause mouth blisters in livestock.
Timothy on the other hand, is a perennial grass that stays alive but remains dormant during the winter. Because of its palatability and the great hay it produces, it has become a beloved favorite of horses and their owners.
While the immature Foxtail plant has no ill effect on horses, the maturing seed heads are troublesome. Each individual seed has an attached “spike” with barbs called “awns”. These can lodge in horses’ mouths and gums, or even scratch an eye. They can also work their way through the tissue, causing lesions and infections. It would be wise to not feed Foxtail, with seed heads, to horses.
So how do we tell these similar looking plants apart? Here are several identifying features to look for:
- Seed head,
- Awns,
- Collar region,
- Plant crown region.
Foxtail Seed head:
Photo: North Carolina State University
This will only be obvious when the grasses have matured and are going to seed, prior to mowing. The Foxtail seed head may droop over, which is a dead giveaway that it is not Timothy. Be aware however, there are several varieties of Foxtail with seed heads that remain upright.
Timothy Seed head:
Photo: Ohio State University
The Timothy seed head stands more erect, and has no awns.
Foxtail awns:
Photo: North Carolina State University
Next, check for the awns, which look like hairs coming off each tiny seed on the head. They give Foxtail its illustrative name. Some varieties may have very long and obvious awns, but others may have shorter awns that may not be as obvious.
Timothy has no awns.
The Collar region:
Pull a leaf away from the stem and examine the juncture where they meet, referred to as the collar region. A magnifying glass or lens will make this examination easier.
Foxtail collar, Photo: Cornell University.
On the Foxtail plant, you will see a fringe of hairs instead of a tall membrane. The leaves of a Foxtail plant may have some hairs as well.
Timothy collar, Photo: Ohio State University.
On the Timothy plant, you will see a tall membrane (ligule) come away from the stem and stand upright.
Plant crown region:
When you dig up the plant, examine the crown, the area where the shoots meet the roots.
Foxtail crown.
Foxtail does not have a crown.
Timothy crown.
Photo: Ohio State University
Timothy has bulb-like structures called “corms” that resemble the bulbs of onion grass.
Control:
Now that you can visually tell the difference between Timothy and Foxtail, what can you do about the Foxtail in your pasture or hayfield? Because it is a grass, it is nearly impossible to eradicate with herbicides that will not also damage your desirable grass. You have 3 options:
1. Renovate your pastures:
If the Foxtail infestation is minor, you can over-seed with desirable cool season grasses in the late summer (mid-August to mid-September as an example) so that by springtime, the new grass can shade out the Foxtail seedlings. If the infestation is widespread and there are not many desirable grasses left in the pasture, you could plow everything under and reestablish the field. This will bury the seeds too deep for them to germinate. Remember to take soil tests and correct pH or nutrient deficiencies before you seed, also avoid grazing the pastures for at least 6 months after seeding to enable the new grasses to establish healthy root systems.
2. Mow Foxtail as it approaches maturity and begins producing seed heads.
If you keep an eye on these plants, you can tell when the seed heads start developing within the sheath (the boot stage). You will need to be able to identify the Foxtail grasses without the seed head present! If you mow between this stage and setting of the full seed, the plant will not be able to drop seeds for the next growing season. Plus, it won’t grow another seed head during this year. There are three important things to remember with this method:
Regular mowing will not fulfill this task completely. Like desirable forage grasses, mowing does not deter Foxtail completely. In fact, if you regularly mow it to a short height, you will end up with very short Foxtail plants with seed heads that are below your mower height. To use the mowing method, you must let the grass grow tall before producing seed heads.
The Foxtail seeds in your pasture most likely germinated at different times in the spring. Therefore, they will not all set seed at the same time, making your observation more difficult. You will need to watch them closely to know when to mow.
There may also be a considerable, multi-generational seed bank in your soil. You will need to follow your mowing procedure for several years in a row before you achieve control. Letting the Foxtail drop seeds just once will replenish the seed bank.
3. Apply a pre-emergent herbicide:
Prowl H2O is one pre-emergent herbicide example approved for pasture use in some regions. Apply in the spring before the Foxtail seedlings emerge to prevent them from growing. It is also effective on other summer annual grasses like crabgrass and some broadleaf weeds.
This method has a few drawbacks. First, it is relatively expensive and two applications are required for maximum effectiveness. Second, the herbicide has a planting restriction of 10 months for grasses. Therefore, if your field had a lot of Foxtail last year and you use this herbicide in the spring, you will have bare ground in its place this season, and cannot reseed with desirable grass until the following spring. Meantime, other weeds may pop up in the bare areas and the bare ground is at a higher risk for soil erosion. It may be wiser to over-seed the pasture in the fall and apply the herbicide in the spring.
Conclusion:
In conclusion, horse owners and hay producers should learn how to identify Foxtail and Timothy grasses. In a severe infestation, eradicating the Foxtail may be difficult and can take several years
Foxtail seed heads, photo by Laura Kenny
