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grassy weed seed head identification

Grassy weed seed head identification

The most effective and proven method of preventing crabgrass from starting is to use a preemergent herbicide. I can’t stress this enough. If you want to prevent crabgrass from ever starting, you have to use a preemergent.

Herbicide Use

Cultural Practices that Help Prevent Grassy Weeds

Crabgrass (Late Spring Annual Weed)

Post-emergence herbicides will be needed once the foxtails have become established. The herbicides containing the active ingredients MSMA or MSDA are labeled for many grassy weeds, including foxtails. Read the label carefully and follow all label instructions. MSMA and DSMA are not recommended for use on St. Augustinegrass, centipedegrass or carpetgrass.

If crabgrass is a problem, avoid fertilizing in late spring and summer. Especially avoid applications of high Phosphorus fertilizers. Phosphorus is essential for seedling growth and will only promote crabgrass establishment.

Appearance: Knotweed is an invasive groundcover with blue-green leaves sparsely appearing on long stems.

Weed Control: Mulch your garden to prevent velvetleaf or use a preemergence herbicide in spring. Pull existing plants by hand or use a postemergence herbicide.

Where It Grows: Sunny or partly shaded lawn, landscape, or garden areas

Where It Grows: Sunny landscape or garden areas

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Type: Annual grass relative

Type: Grass-like perennial

Size: 12 inches tall, 6 – 16 inches wide

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Size: 2 feet tall, 1 foot wide

Appearance: Crabgrass is exactly what it sounds like: A grassy weed. This lawn weed grows roots anywhere the stem makes soil contact. Seed heads spread out like four fingers.

Grassy weed seed head identification

Control: Handpulling with gloved hands is a simple, practical approach to control sandspur in small areas. Improve the health and density of the lawn by fertilizing at the right time and with the correct amount; maintaining an appropriate soil pH; mowing at the recommended height; and watering properly. Apply a 2- to 3-inch layer of mulch to ornamental bed areas to suppress germinating weed seeds.

Joey Williamson, PhD, HGIC Horticulture Extension Agent, Clemson University

Annual bluegrass has smooth, apple-green leaves with two clear lines, one on each side of the midrib that run down the length of the leaf blade. The edges of the leaf tip curve inward like the front of a boat.


Perennial weeds are weeds that live more than two years. They reproduce from vegetative (non-seed) parts such as tubers, bulbs, rhizomes (underground stems) or stolons (above-ground stems), although some also produce seed. Perennial weeds are the most difficult to control because of their great reproductive potential and persistence.

Annual bluegrass (Poa annua) is a cool weather annual grass weed that produces seed heads in the early spring.
Joey Williamson, ©2015 HGIC, Clemson Extension

Selective postemergence herbicides are available for annual bluegrass control. These are best applied in November or early December when the weed is small, thus most susceptible to control. See Tables 1 & 2 for pre-emergence and post-emergence control. Apply all chemicals according to directions on the label.

Original Author(s)

This annual weed can be controlled with a preemergence herbicide applied in early spring (March 1 in the Coastal areas to March 15 in Piedmont areas). Repeat in 60 days. Select an herbicide that can be safely used on your lawn.

See Tables 1 & 2 for pre-emergence and post-emergence control. Apply all chemicals according to directions on the label.