What is Barnyard Grass?
Barnyard grass (Echinochloa crusgalli) is an annual grass weed most commonly found in newly established turf. Barnyard grass tends to be more prevalent when turf is newly seeded during the hot conditions of summer. It grows faster than the desirable grasses that need cooler temperatures to germinate.
Barnyard grass is a coarse annual grass reaching 1 to 4 feet tall, if not mowed. Stems are thick, coarse, mostly upright branching at the base with a purplish-green color. Flower head or seed head is reddish, purplish or greenish color.
Fortunately, coarse Barnyard grass will be killed by the first frost in Fall. The coarse brown grass decomposes in the Spring and the desirable thin bladed grasses fill in the areas with Spring rains and an application of slow release fertilizer.
The lawn above was seeded in the heat of the summer and has a lot of coarse barnyard grass growing with the desirable fine bladed turf grass.
Barnyard grass decomposing in Fall/Spring
Barnyard grass nearly decomposed and fine bladedturf grass seedlings filling in.
Cultural Practices to Minimize Weeds
Management practices that increase the density and vigor of desirable turf grasses tend to discourage competition of weeds. Cultural practices for controlling weeds are aimed at shading and crowding out young weed seedlings by producing dense turf. Effective controls include proper selection and establishment of turf grass, adequate fertilization, proper mowing and watering.
When a lawn becomes weak and results in a thin stand, weeds have an opportunity to grow and compete. Proper establishment and maintenance helps to insure a dense turf which will compete with germinating weed seedlings.
Inadequate fertilization lessens the competitiveness of turf grass, resulting in reduced density and subsequent weed invasion. Adequate nitrogen should be applied to favor desirable grasses. Phosphorus increases seedling vigor and is a factor in reducing weed infestations in newly-established turf.
Improper mowing is one of the most common causes of weed invasion. Mowing heights that are too short result in weak turf grass. Keep the lawn mowed between 2 ½ - 3 ½ inches tall. Use a lower mower setting for higher maintenance lawns that are irrigated and fertilized on a regular basis. Lower maintenance lawns, should be mown at a higher height. Use the 1/3 rule for mowing. (Rule: never remove more than one-third of the leaf tissue at any one mowing.) Example: If maintaining turf at 3 inches height, mow before grass is 4 ½ inches tall. Removing more than one-third of the blade at one time makes the turf more susceptible to environmental stresses (i.e. drought, etc.), slows regrowth, and exposes the soil to light which promotes weed seed germination. Better to mow when needed than on a fixed schedule.
Improper watering also contributes to annual weed problems in turf. Frequent light watering encourages shallow roots and promotes weak turf. Watering less frequently and for a longer duration helps prevents weeds from establishing. Your lawn needs 1” of water a week either from natural rain or irrigation applied in 2 or 3 applications per week.
Chemical Control of Barnyard Grass
Chemical control can help you produce a healthy lawn when combined with good cultural care of your turf. Use herbicides safely by following manufacture labels and directions.
Barnyard grass can be controlled by applying a pre-emergent. A Pre-emergent refers to the use of an herbicide that prevents weed seeds from emerging or kills very young seedlings early in the season without injuring turf grasses. The most common products are labeled crabgrass preventer. The crabgrass preventer will also prevent barnyard grass seeds from germinating. Length of prevention will vary depending on the type of chemical used. The pre-emergent can be purchased by its self or in combination with fertilizer. Do not use pre-emergent if you plan on seeding your lawn because these products will also prevent desirable grass seed from germinating.
An organic product for helping control barnyard grass seeds from germinating is corn gluten meal. This will also prevent grass seed from germinating.
A post emergent product can be used in controlling barnyard grass once it has germinated. The herbicide is sprayed on the growing plant. Results are best when plants are young and actively growing. One such product is Ortho Weed-B-Gon Crabgrass killer.
These cultural and chemical control methods also will help in controlling other annual weeds such as crabgrass, goose grass and foxtail.