Docks

Docks are common, persistent, perennial weeds of agricultural and recently disturbed land and gardens. They are often difficult to eradicate as their deep tap root can regrow from the top section and they produce large amounts of seed.

Broad-leaved dock (Rumex obtusifolius) is a long lived perennial with a basal rosette of long-stalked, smooth ovate-oblong leaves, stems 80cm-1m (32in-3¼ft) high and the distinctive seedheads on spikes that persist into winter. The tap root can be up to 90cm (3ft) in length.

Curled dock (R. crispus) similar to broad-leaved dock but leaves are tapering with a wavy edge and stems 60cm-1m (2-3¼ft).

Docks have a thick, branched tap root that can regrow from the top section if damaged.

Seeds are produced in abundance, germinating readily if left on the surface and are capable of surviving in the soil for up to 50 years. Dock seeds are commonly imported via manure however composted manure, municipal compost and other soil improvers should be free of dock seeds.

Non chemical

Docks are difficult for gardeners to control by cultural methods once established.

Try digging isolated specimens out as only the top few inches of rootstock have powers of regeneration and if 12-15cm (5-6in) can be removed, usually there is no regrowth. Docks are especially vulnerable in spring so digging out at this time should be more effective.

Chemical control

Grassed areas 
Selective weedkillers in lawns:

• Dock seedlings can be killed by spraying with lawn weedkillers based on 2,4-D or MCPA (SBM Job Done Lawn Weedkiller,Vitax LawnClear 2 and Scotts Weedol Lawn Weedkiller), but they become fairly resistant to these weedkillers once they have established a fleshy rootstock
• Lawn weedkillers based on mecoprop-P may check the growth of docks but not completely kill them
• Apply lawn weedkillers in late summer after cutting off the flowering heads to prevent seeding, then re-spray leaves that re-grow 14 days after cutting back

Selective weedkillers in rough grassland:

• Use a selective weedkiller which contains triclopyr (SBK Brushwood Killer) as this would leave the grass unharmed
• This herbicide is systemic, travelling from the weed foliage down into the root system
• However as it is non-selective any broad-leaved plants will be damaged (e.g. wildflowers) and so should only be used in grass where such action is acceptable

Non-selective weedkillers:

• Glyphosate is a more effective treatment for established docks
• Apply when growing strongly from mid-summer onwards
• Glyphosate is not selective and any spray coming into contact with grass around the docks would be killed or severely checked
• Ready-to-use sprays or a gel formulation (Roundup Gel) can make application to individual weeds more accurate

Borders

• Apply glyphosate as a spot treatment to individual plants or spray areas that have been cleared of cultivated plants
• Glyphosate is a non-selective weedkiller applied to the foliage, where it is translocated throughout the weed. Tougher formulations are worth trying (e.g. Scotts Roundup Ultra, SBM Job done Tough Weedkiller (soluble sachet only) or Doff Maxi Strength Glyphosate Weedkiller)
• Being non-selective, it is essential to avoid spray drift onto neighbouring plants. It is important to have good leaf coverage so that as much chemical is absorbed as possible
• Sprays are most effective if applied from early June to mid-August
• As this weed is so persistent several applications may be necessary

Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.

Download

Weedkillers for gardeners  (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 1a,b and 4)

Links

Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale
Weeds: non-chemical control

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Nettles
Thistle: creeping