In the last few weeks, growth rates have improved drastically, and with that has been the emergence of docks in grassland swards, which can be a difficult weed to control.
It is essential that farmers – if they have not already done so – start controlling docks and other weeds on their farm now, to catch the plants in the rosette stage before they are too difficult to kill off.
With the increase in temperature and growth rates, weeds such as docks will begin to persist, damaging the productivity of any sward.
These docks take away nutrients from the grass, as they compete for light and water all while reducing the area for grazing.
As a general rule of thumb, for every 1% infestation in of weeds in a sward, such as docks, the grassland productivity or the forage quality will be reduced by 1%.
Docks in particular can cause a great deal of stress on farmers, as they often persist in nutrient-rich and open swards such silage ground.
They also have a tendency to persist in ground that is spread often with slurry, as slurry is rich in potassium (K), which docks love.
Excess potash in the soil will favour dock growth and so regular soil sampling will allow potash levels to be controlled and prevent a build up.
Controlling docks
The best way to control weeds on farm is through integrated pest management (IPM), which is not only a more sustainable way of controlling perennial weeds, but is also a more cost-effective method.
IPM is simply a way of controlling weeds through liming, crop rotation, drainage, and cultivation techniques, rather than using pesticides.
To apply the principles of IPM to a dock infestation, the farmer should walk the fields to evaluate the level of dock infestation, the stocking rate, fertiliser application and type, soil samples, silage cutting, history of dock treatment and products used, slurry application, grazing management, and drainage.
The best way to tackle docks is a mixture of IPM and chemical spraying, as sometimes you have no option but to select a herbicide and blanket spray when the docks are green, growing, and at the rosette stage.
With heavy weed infestation in old, poor production paddocks, reseeding is the best option, and preferably in the spring, rather than the autumn, as the grass seed establishment and the control of weeds is supported with better weather and grazing conditions.
In terms of chemical control, use herbicides to target the docks and other weeds before they reach 10cm in height, or five to six weeks after reseeding.
If you are controlling docks in paddocks that have not been reseeded, the ideal time to spray is two to four weeks after nitrogen is applied and the weeds are actively growing, but before a seed head appears.
Good fertiliser rates to match your stocking rate, rotational grazing, rotating silage fields for cutting, and topping fields when necessary, are good grassland practices that are needed to maintain a clean pasture.
Late April to early May, or again in late August, is the best time to spray docks. Products with active ingredients of fluroxypyr and triclopyr will give much better control, while products like ProClova will control the dock while protecting the clover.
Early May is a good time to spray, as there are plenty leaves on the dock plant at that stage.
Spraying should be carried out at least three weeks before silage is cut, as most products state this to make sure the chemicals get fully translocated into the root system, which is vital in achieving long-term control.
Always follow the manufacturers recommended guidelines. As we are close to cutting silage, many may have already sprayed the docks on the silage ground, but seek advice to see if another application is needed 10-12 days after silage is cut.
