Weed Biology

Understanding weed biology enables more effective management

A weed is a plant in an undesired place. Weeds can often compete with crop plants for nutrients and resources and/or harbour and spread pests or diseases which infect or degrade the quality of crops. Although many weeds have undesirable consequences they can also provide a key ecological role.

Oilseed Rape Cereals Grassland Other common weeds

Common weed problems in oilseed rape

Thistles in oilseed rape

Thistles are a common weed throughout the UK, growing up to 150cm in height.

Mayweed in oilseed rape

Mayweeds are common and high profile annual or hardy-annual composite weeds.

Blackgrass in oilseed rape

Blackgrass is the most important grassweed infesting cereal and oilseed rape rotations in the UK.

Cleavers in oilseed rape

Cleavers have long caused problems to oilseed rape growers, due to the competitive nature of the weed, and the way it can grow across the canopy late in the season.

Poppy in oilseed rape

Poppies are as competitive as blackgrass and mayweed.

Broad-leaved weeds

Broad-leaved weeds in arable crops.

Common weed problems in cereals

Brome

Bromes in recent years have become more widespread.

Ryegrass

Ryegrass distribution is more widespread and significant where grass leys form part of the rotation.

Wild Oats

Wild oats are distributed from Yorkshire to Devon, and the intense arable areas of south and east Scotland.

Broad-leaved weeds

Broad-leaved weeds in arable crops.

Mayweed

There are several widely distributed species including Scented Mayweed, Scentless Mayweed and Pineappleweed.

Volunteer Beans

Volunteer beans compete with establishing winter cereals in the autumn. Volunteer beans can also cause problems for contact graminicides as large bean volunteers can shade grassweeds and limit contact.

Cleavers

Cleavers infestations have the potential to cause very considerable crop losses.

Poppy

The common poppy is a broad-leaved weed that can be problematic in cereals and winter oilseed rape, competing for nutrients and impacting yield.

Groundsel

Though small, groundsel can grow in large numbers across fields and hence are a very visible weed within crops.

Common weed problems in grassland

Nettles

Grass yield / grazing is lost mainly by competition from nettles for nutrients, light and moisture, but also from stock refusing to graze close to nettles.

Thistles

Thistles compete with grass for space, light, nutrients and water, and they are unpalatable to stock.

Broad-leaved docks

Docks are the most pernicious and damaging of all grassland weeds.

Ragwort

Ragwort poses a serious threat to livestock health. Left unchecked, it can quickly spread and reduce available grazing.

Buttercup

Creeping buttercup is often a severe problem in horse paddocks, where close grazing tends to open the sward.

Curled docks

Curled docks thrive in intensively used and highly fertilised grassland and produce up to 40,000 seeds.

Dandelions

Dandelion is a perennial plant that has a deep taproot and are commonly found where fields are overgrazed, and soil fertility is poor

Common chickweed

Chickweed, if left uncontrolled, will affect the productivity of newly sown leys or a pastures.

Spear thistle

Spear thistle can be found in both newly sown leys and established grassland.

Creeping thistle

Creeping thistle is a perennial that grows from seed or from root sections in the soil.

Broad-leaved weeds

Broad-leaved weeds in arable crops.

Thistles in sugar beet

Yield loss and harvesting difficulties can be caused in sugar beet by infestations of sow-thistle and creeping thistle.

Volunteer potatoes

An integrated approach to the management and reduction of volunteer potatoes is particularly important where less competitive crops, such as sugar beet, are part of the rotation.

Annual meadow grass

Annual meadow grass can be found in both winter and spring crops. These plants compete with the crop for nutrients and water and can delay ripening because it increases the moisture content of the straw and interferes with harvest.

Fat hen

Mature plants are large, fleshy and robust and are competitive with the crop. In spring planted crops they grow rapidly and can smother spring cereals, sugar beet and maize crops.

Bur chervil

Bur chervil can grow into large, robust plants that cause difficulties at harvest. There are limited choices of product for controlling bur chervil.

Cranesbill

Mature plants can be prostrate or upright in growth and are competitive with the crop. In spring planted crops they grow rapidly and can smother cereals, oilseed rape and maize crops.

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Weed Biology

Understanding weed biology enables more effective management

Common weed problems in oilseed rape

Thistles in oilseed rape

Mayweed in oilseed rape

Blackgrass in oilseed rape

Cleavers in oilseed rape

Poppy in oilseed rape

Broad-leaved weeds

Common weed problems in cereals

Brome

Ryegrass

Wild Oats

Broad-leaved weeds

Mayweed

Volunteer Beans

Cleavers

Poppy

Groundsel

Common weed problems in grassland

Nettles

Thistles

Broad-leaved docks

Ragwort

Buttercup

Curled docks

Dandelions

Common chickweed

Spear thistle

Creeping thistle

Other common weed problems

Broad-leaved weeds

Thistles in sugar beet

Volunteer potatoes

Annual meadow grass

Fat hen

Bur chervil

Cranesbill