Little Barley Hordeum pusillum
An increasing weed problem in lawns over the past decade is a winter annual grassy weed known as little barley. The plant germinates from seed in September and October. In the spring it starts growing early, grows rapidly, produces many seed heads and then dies by early summer. Like many weeds it is going to show up in areas where turf is thin or non-existent. After the heat and drought of 2012, many lawns were thinned by the stress and this plant became abundant. By late June, areas of lawns may well look like Figure #1.
Figure #1 - Little barley seed heads in a Bermudagrass lawn.
The areas of brown are the seed heads from the plants that became established because of thin areas in the Bermudagrass. Upon closer examination of the turf, the maturing seed heads of the little barley are very obvious (Figure 2). If left unmowed, little barley can grow to nearly a foot in height and have many seed heads (Figure 3).
Figure 2 - Closeup of little barley seed heads.
Figure 3 - Unmowed little barley with seed heads.
But more typically, the plant is mowed off on several occasions resulting in smaller heads and lower emerging heads (Figure 4).
Figure 4 - Little barley plant that has been mowed on several occasions and is reaching full maturity.
Besides being an unsightly nuisance in yards, the seeds from little barley can become an annoyance to humans as they become stuck in clothing, and a real health nuisance to pets as the seeds become entangled in fur or work their way into the foot pads of pets creating discomfort and injury. Figure 5 shows the seeds and why they can work their way into clothing and become difficult to remove.
Figure 5 - Little barley seeds showing backward facing awns that can make removal of seeds difficult from clothing, pet fur and pet's feet.
Little barley starts dying down in June and is dead by early July. Treatment in May or June is really a waste of time. Ultimately, the best control is to have a thick aggressive lawn that is mowed tall. To control this annual grass in the short run though requires using a weed preventer in late summer so that germination doesn't occur in the fall. Dimension does have "Barley - Hordeum spp" on the label so this would include little barley. Remember that these pre-emerge products much be applied and then activated with 1/2 inch of rainfall or irrigation before they will be effective.