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Don't Let Docks Limit Grassland Output

06 June 2017
Type Media Article

By Anthony O'Connor, Teagasc Adviser, Galway/Clare Regional Unit & Shay Phelan, Tillage Specialist, Teagasc

Docks are a major, deep rooted, persistent weed problem on many farms. Docks will seriously limit grassland output and productivity unless controlled.

Cultural Control:

The best control of all for docks is good grassland management. Maintaining a dense, leafy grass sward will smother out emerging docks. In this regard, having a fertile soil with adequate levels of Nitrogen, Phosphorous and Potassium along with a suitable pH for grass growth is hugely important. Avoiding poaching and overgrazing will limit the space for docks to emerge. Tight grazing and heavy regular silage cuts leave open swards. Open swards promote docks. The dock seed needs light, air and plenty of nutrients to establish. A harvested silage field is a good environment for the dock. Docks are associated with slurry. Teagasc research has shown that docks germinate and thrive better where there are high potassium (K) levels. Regular slurry applications build up or provide K for dock establishment.

Chemical Control:

Where heavy infestations occur, use of chemical herbicides may be needed.

General Dock Control:

  • Apply the herbicide onto actively growing weeds and nutrients which are actively being transported to new foliage and roots.
  • If seed stalks are seen on the plant or if the dock has diseased leaves or is under pest attack it is better to cut/top or graze and allow re-growth of the docks before applying chemical.
  • Allow adequate time between spraying and cutting silage for the herbicide to work, especially where weeds have a developed taproot.
  • Avoid spraying in very dry or cold conditions.
  • Remember to keep the prescribed cross-compliance records and follow the product label

The best time to spray is before stem formation in late July. This is when the dock plant has plenty of leaves to absorb chemicals in herbicide being used.

Season Long Dock Control:

  • Use of herbicides based on Aminopyralid, Dicamba, Triclopyr, Fluroxypyr, etc., will give season long control plus a wide range of common grassland weeds. These products will eliminate clover.
  • Treat when the docks are actively growing, in the rosette stage up to 25cm high or wide.

Chemical Control in Non-Clover Grassland:

Where clover is of no consequence, products such as Bandock, ForefrontT, Dockstar Pro, Pastor Trio, High Load Mircam Super, Lupo, Thrust, Kildock, CroplinkD50 will kill established docks, but they will also kill/damage clover plants. ForefrontT cannot be used on silage ground. Docks should be sprayed before they start to limit sward productivity. Any spraying should be carried out at least fourteen days in advance of any cutting, thus allowing the sprayed docks to wither and sward close in. Follow manufacturer's instructions carefully when using these herbicides.

Chemical Control in Clover Rich Swards:

Where clover is of consequence, the following herbicides, Eagle and Prospect may be applied. These products do not harm clover but Prospect may have some effect on the constituent grasses of swards. They will give season long control of docks. The higher rate should be used where the infestation is high or the docks have a well-established tap root. Most broad leaved docks will be at the correct stage for weed control in the next few weeks - See Table below;

Herbicides for Dock Control in Established Grassland:

ProductsChemicalRate/HaComment
Eagle Amidosulfuron 75% 40-60 g Controls both broad leaf and curled docks. No effect on clover. Should not be used in very dry weather. Costs €37 to €56/ha
Asulox
Prospect
Asulam
Thifensulfuron-Methyl
N/A
15g sachet
Awaiting emergency use clearance for 2017 Does not affect Clover but may retard grass growth in certain conditions. Allow 7 days after application of Prospect before cutting or grazing. Price €29/ha
Forefront T Triclopyr Aminopyralid 2.0 L Apply at rosette stage. Also controls a wide range of weeds incl. thistles, nettles, ragwort etc. €78/ha. Should be applied on grazing ground only.
PastorTrio Fluroxypyr + Clopyralid + Florasulam 2.0L Controls many weeds such as chickweed, fat-hen, mayweeds, buttercups, docks and thistles
Envy Fluroxypyr + Florasulam 2.0L Additional control over straight fluroxpyr where temperatures fluctuate. Strong on chickweed,
Binder/Hurler & various Fluroxypyr 2.0 L Controls Dandelions, Nettles and established Docks. Cost €28+/ha at 2 L rate
DoxstarPro Triclopyr + Fluroxypyr 2.0 L Controls docks and dandelions. 1.0 L/ha fb 1.0 L/ha. €35/ha
Hiload Mircam Hygrass Dicamba + CMPP-P 1.25 L 5.0 L Hygrass Controls broadleaf and curled Docks, Chickweed, thistles and Nettles etc. Price range €30 +/ha
Lupo 2,4-D + MCPA 4.0 L Controls Ragwort, Rushes, Thistle, Buttercup, Nettle, and a broad range of weeds with suppression of broadleaf and curled Docks €30/Ha
Thrust Dicamba + 2,4-D 3.5 L Includes high rate of Dicamba and 2,4-D. Excellent control of Ragwort, broadleaf and curled Docks and a wide range of weeds incl. Buttercup, Nettle, Thistle etc €42/ha

Prices exclude VAT and are a guide only. Products containing Mecoprop-p will be re-registered this year, professional use application onto grassland will be removed.