Annual blue-eyed grass (Sisyrinchium rosulatum Bickn.) is a cool-season annual weed common throughout Louisiana. It has grass-like leaves but is a member of the iris family. Annual blue-eyed grass produces flowers in early spring and spreads through seed. It can tolerate most soil types but is often observed growing in moist areas. This weed typically grows in small, tight bunches in the turfgrass.
Annual blue-eyed grass has bright green, flat leaves with smooth edges that taper into rounded tips. Leaves grow in tight clusters, forming a basal rosette. Flowers grow singly on zig-zag-like stems that extend from basal clusters. Flowers are typically white to light purple with a dark purple ring around the center of the petals. Fruit is spherical and reddish-brown in color. Annual blue-eyed grass has a bunchlike growth habit. For more information on annual blue-eyed grass identification and characterization, visit the USDA Plants Database at https://plants.usda.gov.
The best way to prevent or reduce weed encroachment is to maintain a healthy lawn through proper fertilization and soil pH and regular mowing. Properly maintaining a lawn through these cultural practices promotes dense and vigorous turfgrass, allowing it to better compete with weeds. Below are the recommended mowing heights and nitrogen fertility rates recommended per turfgrass species. In addition to these lawn care practices, manual removal of weeds may also be necessary.
In addition to cultural practices, herbicide applications may be required to achieve effective weed control. Several pre-emergence herbicides applied in the early fall provide good control of annual blue-eyed grass. Although blue-eyed grass is an iris, it is susceptible to broadleaf herbicides as well. Herbicides that contain metsulfuron are generally most effective on this weed.
When applying any type of herbicide, you must follow the manufacturer's labeled directions. For more information regarding pesticides for turfgrass, please reference the Louisiana Suggested Chemical Weed Control Guide.
The LSU AgCenter and the LSU College of Agriculture