A dense, healthy lawn is the best defense against weeds. Proper variety selection and management practices are vital to preventing or limiting weed infestations. For example, using mowing heights at the higher end of the recommended range can significantly reduce infestations of weeds such as crabgrass, while over-irrigating can make weeds such as nutsedge more problematic.
Too much shade can cause turfgrass to lose density and allow shade tolerant weeds to thrive. When weeds are present, it is important to identify and address the cause of thinning turfgrass before treating for weeds.
To control weeds in home lawns, please consider the following:
1) Determine whether it is a grassy weed, broad-leaf weed, or sedge. Broadleaf weeds such as clovers (Trifolium and Medicago sp) and dandelion (Taraxacum officinale) usually have net-like leaf veins though leaf shapes vary widely (Figure 4). Grassy weeds such as crabgrass (Digitaria sp) and dallisgrass (Paspalum dilatatum) have parallel leaf veins and long, slender leaves. Sedges (Cyperus spp) such as yellow nutsedge (aka nutgrass) look similar to grasses but have a triangular stem. Identification tools and an image gallery of over 100 common Texas weeds are available at: https://aggieturf.tamu.edu/
2) Determine the weed’s life cycle. Summer annual weeds such as crabgrass and spurge (Chamaesyce sp) germinate in the spring, grow for several months, and then flower, set seed, and die in the fall. Conversely, winter annual weeds such as henbit (Laminum amplexicaule) and rescuegrass (Bromus catharticus) germinate in late summer/early fall, grow throughout the fall and winter, and then flower, set seed and die in the spring. Perennial weeds such as clovers, dallisgrass, and nutsedge may grow during warmer or cooler months, but have perennial structures year-round.
For more information on this or any other agricultural topic please contact the Hopkins County Extension Office at 903-885-3443 or email me at m-villarino@ tamu.edu.