Carolina foxtail (Alopecurus carolinianus) and little barley (Hordeum pusillum) are cool-season grasses that can be seen in Missouri croplands, pastures, roadsides, etc. (Figure 1). Both are native species and can be found in most continental U.S. states. Carolina foxtail, which is not directly related to the summer foxtails, is commonly found in moist areas of fallow agronomic fields and has been shown to be a potential host for fungi that cause diseases such as Rice blast<sup>1</sup>. Little barley is most commonly found in wheat-producing areas of the state, mostly north of the Missouri river. However, the grass can also be found in pastures, where its dense mat can suppress and delay the greening of more desirable forage grasses.
Both grasses tend to have erect stems, although the Carolina foxtail stem can occasionally be bent. Carolina foxtail will grow from 4 to 6 inches in height while little barley can range from 4 inches to 2 feet. The leaf blades of Carolina foxtail are rough and may reach 6 inches in length; the leaf tips are pointed and can be sharp. Little barley leaf blades may be glabrous (lacks hairs) or have short hairs on both the upper and lower leaf surface, and the blades can reach up to 8 inches in length. The leaf blades of both grasses are less than ¼ inch in width. Both plants lack auricles, and have thin membranous ligules at the junction where the leaf blade meets the stem (Figure 2). However, the ligules on little barley tend to be much smaller than those on Carolina foxtail, which are also small and approximately 1/8th of an inch. The leaf sheath of Carolina foxtail lacks hairs while little barley may or may not have short hairs present on the sheath.
The seed head of Carolina foxtail has a cylindrical shape that can be up to 2 inches long (Figure 3). Little barley has a seed head that is made up of flattened spikes and is more grain-like. The stiff awns tend to be less than ½ inch in length (Figure 4) and can injure grazing livestock.
Carolina foxtail seed viability is short-lived; however, the grass is capable of producing seed in spring or autumn, and this helps to ensure persistence of the grass population<sup>2</sup>. In general, Carolina foxtail is easy to control, and currently no known instances of herbicide-resistant Carolina foxtail are known. The best time to control the grass is in the fall or early spring, prior to seed set. Glyphosate and paraquat provide effective non-selective control. Spring applications of atrazine (4 pts/A) following wheat harvest and prior to weed emergence in field going to corn or sorghum or Canopy EX (chlorimuron + tribenuron) (1.1 to 3.3 oz/A) prior to soybean planting have been shown to be effective. Applications of Basis (0.33 to 0.5 oz/A) or Simazine (1 qt/A) after fall harvest and prior to emergence of Carolina foxtail have also shown good control.
Little barley is also best controlled in the fall or early spring. Gramoxone (paraquat) can provide effective burndown of little barley; however, continual use of the herbicide is likely to lead to paraquat-resistance as has occurred in a closely related species, smooth barley. Spring applications of Olympus (0.91 oz/a) or Maverick (0.67 oz/a) have shown 98 to 100% control of little barley 28 days after treatment<sup>3</sup>. A fall application of Olympus (0.91 oz/a) with Axiom (10 oz/a) or a Maverick (0.67 oz/a) application each provided only 50% little barley control when observed 28 days after treatment; however, control had increased to 95-97% when observed again the following April<sup>3</sup>. Sencor is another option for post-emergence control in select winter wheat varieties with metribuzin tolerance and can be applied at rates of 2 to 3 oz/A when wheat is at the 2-leaf to the 2-tiller stage; 5 to 6 oz/A from 3 to 4-tiller stage; and 5 to 8 oz/A when wheat has more than 4 tillers.
With regards to little barley control in pastures and hay fields, researchers in Alabama have found that late winter/early spring treatments including Accent (nicosulfuron) at 1 oz/A provided greater than 90% control of little barley 6 weeks following herbicide application. With the addition of metsulfuron (0.4 oz/A) and 2,4-D Amine (1 lb active ingredient/A), little barley control reached 97% six weeks after treatment4. Glyphosate at a low rate of 14 fl oz/A provided 90% or greater control at 3 weeks following treatment and over 95% control 6 weeks after the application4.
Atrazine can also be used for little barley control; however, an 18-month grazing and/or foraging restriction will likely apply to almost any subsequent crop following atrazine treatment. As in all weed management programs, tank mixes and herbicide rotations should be implemented in the control of these grasses to avoid the development of herbicide resistance.
Source:missouri.edu