How to Control Weeds in Your Silage Ground

James Bourke, B.Ag.Sc.

Docks are a common, deep rooted, persistent weed problem on many farms. The perennial broadleaf weed will seriously limit grassland output and productivity unless managed correctly.

The best control of all for docks is good grassland management. Maintaining a dense, leafy grass sward will help to 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 massively important. Also, avoiding poaching and overgrazing will limit the space for docks to emerge. Open swards after tight grazing and heavy regular silage cuts promote docks. A freshly cut silage field leaves a perfect environment for dock seeds to establish. The dock seed needs light, air and plenty of nutrients to establish. Teagasc research suggests that docks germinate and thrive better where there are high potassium levels. Regular slurry applications build up or provide K for dock establishment.

General Dock Control

• The best time to spray is before stem formation when it’s the size of a dinner plate. This is when the dock plant has plenty of leaves to absorb chemicals in herbicide being used.

• Apply the herbicide onto actively growing weeds and nutrients which are 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 or graze and allow re-growth of the docks before applying herbicide.
• Allow enough time between spraying and cutting silage for the herbicide to work, especially where weeds have a developed taproot.
• Avoid spraying in very dry and hot, or cold conditions.
• Remember to keep the prescribed cross-compliance records and follow the product label.
• Treat when the docks are actively growing, in the rosette stage up to 25cm high or wide.

Chemical Control in Clover and Non-Clover Grassland

Regarding chemical control of dock, if protecting clover is a must, Eagle is the product of choice. If protecting clover is not a priority, any one of Forefront T, Envy, Pastor Trio, Doxstar Pro, Pasture Pack, and Hurler are an option and should be chosen based on price point, and variety of weeds controlled.

James Bourke is the Dairygold Grassland Specialist, providing a free advice service to our customers. Please contact James on 086 793 8408 or your Area Sales Manager for any queries on which product suits your needs and more information on offers.