Annual BlueGrass Poa Annua
Annual bluegrass grows to a height of 6 to 8 inches when left unmowed. It has light green, flattened stems that are bent at the base and often rooted at the lower stem joint. Leaf blades are often crinkled part way down and vary from 1 to 3 inches in length with typical Poa, boat-shaped leaf tips. The inflorescence (flowering structure) is a terminal panicle that varies from 1 to 4 inches in length. Seed head initiation can start as soon as plants are 6 weeks old in early fall and continue until early summer, but most seed heads are formed in spring. The annual form of annual bluegrass is a rapid and prolific seeder.
Crabgrass (Digitaria Genus) is a common, slender annual and perennial weed. Digitus is the Latin word for “finger”, and they are distinguished by the long, finger-like inflorescences they produce. Typically, it has spreading stems with wide, flat leaf blades that lie on the ground with the tips ascending. The inflorescences is a panicle in which the spike-like branches are arranged in a digitate fashion. The spikelets are arranged in two rows on an angled or winged rachis. Each spikelet has two florets, only one of which is fertile. The first bracts at the base of the spikelets are either very minute or absent. Crabgrass has a long germination period, and if conditions are right, it can germinate throughout the growing season.
Dallisgrass is a coarse-textured grass that grows in a clump and slowly increases in diameter as its shallow, underground stems (short rhizomes) grow outward. The rhizomes have short internodes (the length of the stem between the joints) that look like concentric rings on its surface. The presence of these distinctive rhizomes is a good way to distinguish dallisgrass from other common clumping grasses in lawns, such as crabgrass. As the clump matures, the center may die and a different grass or weed may be growing in its center.
Although nutsedges resemble grasses and often are referred to as “nutgrass,” they aren’t grasses but are true sedges. Their leaves are thicker and stiffer than most grasses and are arranged in sets of three at their base; grass leaves grow across from each other in sets of two. Nutsedge stems are solid, and in cross section they are triangular; grass stems are hollow and round, and in cross section they are almost flat or oval. Nutsedge has three long, leaflike bracts at the base of each flower head. Yellow nutsedge has light brown flowers and seeds.
Both are winter perennials, with wild garlic being predominant in South Carolina. They emerge in late Fall from underground bulbs and grow through the Winter and Spring. In late Spring, aerial bulblets are formed and the plants die back in early Summer. The underground bulb persist in the soil for several years. While both have thin, green, waxy leaves, those of wild garlic are round and hollow, while those of wild onion are flat and solid. Unfortunately, there are no pre-emergence herbicides that will control wild onion or wild garlic. They must be treated with a post-emergence herbicide, and persistence is the key.