Weeds - Grass Weeds Information and Photo Gallery

Perennial rye-grass


Perennial rye-grass (Lolium perenne L.) averages a height of 10 -90 cm high when mature. Leaves are folded in the bud (in contrast to annual rye-grass (Lolium multiflorum) in which the leaves are rolled). Leaf blades are 2 to 6 mm (0.08-0.24 inches) wide, 5 to 15 cm (2-15 inches) long, sharply taper-pointed, and keeled. Blades are bright green, prominently ridged on the upper surface, and smooth, glossy, and hairless on the lower surface. Leaf margins are slightly rough to the touch and are covered with minute serrations. Leaf sheaths usually are not keeled, smooth, compressed and sometimes almost cylindrical, pale green, and reddish at the base. Sheaths may be closed or split. The collar is narrow, distinct, glabrous, and yellowish to whitish-green.

Auricles are small, soft, and claw-like. The ligule is thin-membranous, from 0.5 to 2.5 mm, rounded at the apex, and may be toothed near the apex. Perennial rye-grass has a bunch-type growth habit; folded vernation; small auricles; ribbed blade, purple colour at base; underside of leaf is glossy. Spikelets are stalkless, alternating on opposite sides of the axis.

It is valuable as a nutritious and palatable grazing material and for hay.

Occurrence and spread

Despite is name Perennial rye-grass is not related to cereal Rye. It can be found throughout the United Kingdom but prefers rich and heavy soils in the lowlands.

Control and management

Rye-grass is extremely competitive with wheat and barley crops and can greatly reduce yields.  Tralkoxydim (e.g Grasp) is an effective herbicide rye-grass control in both wheat and barley. Best applied when ambient temperatures are 4C or above for the period at and after application, ideally, it should also be a period when the daily fluctuation in temperature is small.

Although cereals, generally, benefit from early removal of grass weeds, because ryegrass can continue to germinate well into spring, it may be better to wait until as much has germinated as possible. Consequently, herbicides such as Grasp are often best applied during the later part of the spray window, when the ryegrass is between GS 32-33. Seek advice from your BASIS qualified adviser.

ADLib logo Content provided by the Agricultural Document Library
© University of Hertfordshire, 2011