Arable weeds: Which brome species is in your field?

Bromes are highly competitive weeds, especially in cereals. As the species present determines the most appropriate management response, it is important to identify which ones are in your fields.

With two major groups and five main arable weed species, brome grasses are relatively diverse. By understanding this diversity, it is easier to identify the species present and the best management tactics.

Species identification is easiest once seed heads are visible (usually June–July).

Anisantha species included barren (sterile) brome and great brome.

It is best to bury the seeds of these species as soon as possible after harvest (unless chopped straw provides adequate cover).

Scientific name: Anisantha sterilis.

Yield loss: It is highly competitive. 3 plants/m² can cause 2.4% yield loss in winter wheat.

This annual tufted grass grows to 100 cm in height and is most abundant of the UK brome weed species. The leaf blades are green, turning purple, and are finely pointed and covered in short hairs. The ligule is also pointed. The awned (15–30 mm), drooping flower head is tinged with purple after flowering.

Figure 1. The head (left), ligule (middle) and seed (right, with scale in cm) of barren (sterile) brome

Scientific name: Anisantha diandrus.

Yield loss: 3 plants/m² can cause up to 2% yield loss in winter wheat.

Great brome is an annual grass that grows to a height of 35–90 cm. It is loosely tufted or solitary plant, with a spreading habit. Leaves are hairy towards the top of the plant. Awn-length ranges between 35–60 mm. Flower heads are very open with single spikelets on each branch.

Figure 2. The head (left), ligule (middle) and seed (right, with scale in cm) of great brome

The Bromus species include meadow brome, rye brome and soft brome.

*Soft brome only

Leave the seeds of this species to ripen on the soil surface for one month before cultivating. Identify Bromus species by looking at the awns/panicles (flowering heads), which are tighter and neater than Anisantha species.

Scientific name: Bromus commutatus.

Yield loss: 3 plants/m² can cause up to 2% yield loss in winter wheat.

It is an annual or biennial grass, 40–120 cm tall. It is loosely tufted or solitary, with slender to moderately stout hairy stems, rough finely pointed leaf blades and tubular splitting sheaths. The flower heads are loose and drop to one side.

Figure 3. The head (left), ligule (middle) and seed (right, with scale in cm) of meadow brome

Scientific name: Bromus secalinus.

Yield loss: 3 plants/m² can cause up to 0.5% yield loss in winter wheat.

Rye brome is a robust annual grass, with stems about 50–100 cm tall. Leaf blades have rough surfaces and are pointed. The leaf sheaths are usually hairless. However, the lower ones can be sparsely hairy. It has flattened spikelets with relatively short awns.

Figure 4. The head (left), ligule (middle) and seed (right, with scale in cm) of rye brome

Scientific name: Bromus hordeaceus.

Yield loss: 3 plants/m² can cause up to 2% yield loss in winter wheat.

Soft brome is a tufted annual grass that hybridises with related species. It grows to a height of 10–100 cm. Mature plants have dense soft hairs on the leaf sheaths and the stems are very hairy. The leaf blades are greyish-green and the flower head is compact and upright (more upright than meadow brome).

Figure 5. The head (left), ligule (middle) and seed (right, with scale in cm) of soft brome

Image sources: ADAS 2014 (AHDB Information Sheet 31)