Setaria glauca, commonly known as yellow foxtail, is an annual summer weed with shallow roots that is usually found in pasture and turf areas. Many confuse it for green foxtail, which looks similar but has a thinner stem and longer bristles. Another weed that looks similar is knotroot foxtail. The seed head of yellow foxtail is spiky, yellow-green in color, and contains numerous bristles on each seed. Its ligule and leaf margins have dense hair fringes, while the leaf blades of yellow foxtail have longer hairs.
Yellow foxtail is native to Europe, but can now be found throughout the United States and most of Canada. It mainly grows in the same areas where green foxtail is found and heavily competes with grains, vegetables, row crops, vineyards, and orchards. In addition to crowding out crops, an overabundance of yellow foxtail can lead to abnormal growth in surrounding species due to taking up the soil’s nutrients. Tomatoes and cabbage may be especially affected by yellow foxtail, as studies have shown that the weed is capable of allelopathy. This phenomenon occurs when invasive plants release biochemicals through their roots to reduce competition from nearby species.
Though animals can use yellow foxtail for forage, its disadvantages generally outweigh the risks of planting it or allowing it to invade turf and growing areas. Controlling a yellow foxtail invasion can be difficult as its seeds can germinate for an entire summer. Pre-emergence herbicides are key when applied at the optimum time, but the products that need to be used require licensing so there is no real option but to turn to a credible lawn service that offers a weed control program that controls lawn weeds.