Blackgrass
Alopecurus myosuroides
Washington State Classification
Class C — Widespread, County-Selected Control
In Europe, it is known as one of the most noxious weeds of small grain fields.
Quick Reference
Identification
Growth Habit
Blackgrass is a tufted annual with stems that are upright or spreading then upright and can grow to 32 inches tall.
Leaves
Leaves alternately arranged on stems and have open leaf sheaths. Flat leaf blades are 0.08 to 0.16 inches (2 to 4 mm) wide. The upper surface is rough while the lower surface is smooth. Ligules somewhat torn (lacerate) and 0.08 to 0.20 (2 to 5 mm) long.
Flowers
Flowers are in dense spike-like seed heads. Each seed head is 1 to 5 inches long and is tapered at each end. They are purplish in color and appear black from a distance. Flowers bloom from June to August.
Fruit & Seeds
High seed production and seeds are about 0.1 inches (2.5 mm) long.
Impact
In Europe, it is known as one of the most noxious weeds of small grain fields. In Washington, it is a serious threat for agricultural crops such as wheat. Blackgrass was changed from a Class B to a Class C noxious weed in 2013.
Ecology & Spread
Habitat
Blackgrass can be found in waste areas, fields, grain fields and wet areas. Please click here to see a county level distribution map of blackgrass in Washington.
Spread Mechanisms
Reproduction
Blackgrass reproduces by seed.
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