Darnel ryegrass as a dangerous weed of grain crops

Darnel ryegrass is a dangerous grassy weed that infests crops of spring cereals (especially small-seeded cultivars of spring wheat) and other cereal crops. The weed is widespread in the European part of the Russian Federation, the Caucasus, and Western Siberia. The presence of its fruits in the harvest poses a serious threat to grain quality and product safety.

Poisoning with temulin in humans and livestock animals manifests with characteristic symptoms:

• dizziness;
• tinnitus;
• pronounced weakness;
• loss of consciousness;
• convulsions.

Morphological features and dimensions of caryopses

Darnel ryegrass infests grain products with fruit-caryopses, membranous caryopses (enclosed in flowering glumes), or spikelets. The spikelets of the weed are three- to eight-flowered; they consist of one or more membranous caryopses covered by glumes. The membranous caryopsis itself has a boat-shaped-oval, wide-open form with a long awn, and it is noticeably swollen in the middle part on the ventral side. The apex of the seed is bluntly rounded, and the base is truncate.

The outer flowering glume is leathery, often bidentate at the top, with three prominent veins and short-ciliate margins. The inner glume is two-keeled, almost equal to the outer one, wavy-jagged, membranous at the top, and often furrowed in the middle. A flexible, long, and slightly wavy awn extends from the middle vein; it has slight serration and breaks off easily. The rachilla is flattened, straight-truncate, and about 2 mm long. The surface of the seed is glabrous, slightly rough, sometimes with light longitudinal wrinkling. The color varies from grayish-green to dirty yellow, with a darker upper part.

The caryopsis freed from the outer glumes is dark brown, oval-ovate, convex on the back, with a fused inner flowering glume. A wide and shallow groove is clearly visible on it, and the embryo is characterized by high width. The length of such a caryopsis is 45 mm.