ADLib Glossary (C)

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Cleavers are an annual dicotyledonous weed common on arable land. It reproduces by seed and prefers damp, moist soil. The seedling has oblong cotyledons, a square stem with downward pointing hairs, and true leaves in whorls. It climbs using the crop as support.

When mature, the stems are square, with short, bristly downward pointing hooks growing on corners, generally 60-120 cm (2-4 ft.) long and trailing.

The leaves are in whorls, in groups of 6-8 running up the stem. They are pointed at the tip, roughened, and 2.5-7.5 cm (1-3 in.) long. The flowers, which occur in summer, are white, small, and produced in the axils of upper leaves. The seeds are grey-brown, rough, and bristly. A single cleavers plant can produce 3,500 seeds.

Cleavers seed becomes dormant in dry soil. The seed can remain viable for 1-3 years after which they tend to decay. Seeds remain viable when eaten by animals. It is easily spread by harvesting equipment and in contaminated manure. The bristly seeds cling to the hair and wool of animals and to clothing. They have a very characteristic emergence pattern observed in autumn sown crops. Cleaver seedlings emerge in a flush shortly after the crop is drilled. This flush is more prolonged than many other arable broad-leaved weeds and is often followed by a second flush in spring the following year.Research indicates that germination is triggered by a number of factors such as soil temperature and moisture as well as cultivation.

Partly because of the size of the plant cleaver infestations have the ability to cause very potential crop losses. because of this attention tends to be given to control growth of the weed during the current year. In reality a successful weed management strategy for cleavers and other weeds must address the long-term population dynamics of the species.

Use certified seed that is free of cleavers. All grades of pedigreed seed must be free from cleavers seed.

  • Clean tillage and harvesting equipment before changing fields.
  • Winter annual cleavers should be controlled in the autumn after germination with tillage or a herbicide.
  • Herbicide options are available for most crops.

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