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Weeds and Their Control: Yellow foxtail (Setaria glauca)

setacia-glaucaThis warm-season annual weed originated in Africa but has spread throughout Eurasia and North America . It is found throughout the US where it often invades moist fertile lawns, croplands, gardens, and nurseries. A member of the grass family (Poaceae) it can be difficult to distinguish from other common weeds such as crabgrass until it blooms.


Yellow foxtail grows in clumps and has flattened stems that may be tinted red and branch from the base. The flat leaves are up to twelve inches long and have rough edges and conspicuous hairs on the upper surface near the base. The seed head is produced in summer and is a bristly, cylindrical panicle up to five inches long. It turns yellow when mature as indicated by the common name yellow foxtail. Thousands of seeds are produced and germinate in the spring. The root system is fibrous.


Dense turfgrass may inhibit the growth of yellow foxtail. Because the weed is an annual, consistent mowing before seed production will greatly reduce its return in following years. In severe cases, the application of a pre-emergent herbicide one or two weeks before the seeds germinate in late spring is effective. Likewise, the application of a post-emergent herbicide after seedling emerge reduces the weed population.