When conditions became suitable for spraying, many first-cut silage crops were too advanced for a pre-harvest application and farmers had no option but to take the hit on yield and quality due to heavy dock infestations.
Where docks were not controlled before silage was cut, there is now a golden opportunity to get rid of the weed and have a clean, productive sward for a second cut of silage or for subsequent grazing.
Dock-infested silage swards that were cut in recent weeks are now at the ideal stage for spraying with an effective herbicide and when it comes to choosing the most effective product, there is nothing to beat the systemic herbicide Doxstar Pro.
In the video below, technical manager with Whelehan Crop Protection Chris Maughan outlines how to get the most from your application of Doxstar Pro.
Manufactured by Corteva Agriscience and distributed on the Irish market by Whelehan Crop Protection, Doxstar Pro contains two powerful chemicals - triclopyr and fluroxypyr - ensuring the most effective kill of the dock root system, which can be up to one metre deep.
It is also highly effective on chickweed and dandelions and, unlike dicamba-based products, it does not result in any check to grass growth.
Timing of the spray
Chris stressed the importance of timing of the spray in achieving best results from Doxstar Pro.
“For best control, docks should be sprayed when they are actively growing and are 15cm to 25cm high or across and before a seed head begins to appear,” said Chris.
“Dock-infested silage fields that were cut in recent weeks should now be at the right stage for spraying with Doxstar Pro.
“If the sward is closed for a second cut of silage, it is important to leave at least three weeks between spraying and harvesting the crop.
“This will ensure that the chemicals get fully translocated down to the dock roots, a vital factor in achieving an effective kill.
“If the sward is being grazed, keep animals off the pasture for seven days after spraying,” he advised.
Devastating impact on yield
The importance of controlling docks is emphasised by the impact they can have on grass and silage dry matter yields.
Teagasc research has shown that a 10% infestation of docks can cut silage dry matter yield by 10%.
A severe infestation can reduce dry matter yield by up to 50%.
Silage quality is also reduced through poorer fermentation. And dock stems can do serious damage to the quality of baled silage through puncturing of the film.
Doxstar Pro application rate
Apply Doxstar Pro at 2l/ha as a single application or two applications of 1l/ha six to 12 months apart.
Use a minimum of 300 litres water/ha (30gals/acre).
When using low-drift nozzles, for example guardian air nozzles, water volume can be reduced to 200 litres/ha.
When it comes to choosing the perfect broad spectrum weed killer for grazing pastures, Forefront T provides the highest level of control.
Imbued with the most advanced chemistry in weed control technology, Forefront T has become the product of choice for a growing number of farmers seeking to clean pastures of a wide spectrum of weeds.
It contains two chemicals - aminopyralid and triclopyr.
This powerful combination makes it the perfect choice for a wide range of weeds, including docks, thistles, nettles, chickweed, dandelions and buttercups.
As with Doxstar Pro, best results are achieved by spraying with Forefront T when weeds are actively growing and are at the right stage for a good kill of the root system.
Ideal growth stages
Docks should be 15cm to 25cm high or across and before a seed head begins to show. Thistles should have four to 10 leaves and be 15cm to 25cm high. Nettles should be sprayed before flowering.
Weeds are now likely to be gone beyond these stages in many grazing pastures. It is therefore best to graze out the pasture and top it.
After around three weeks of regrowth, the weeds should be at the ideal stage for spraying with Forefront T.
Apply Forefront T as a single application at 2l/ha in a minimum of 200 litres water/ha. Keep stock off the pasture for seven days after spraying.
Where thistles are the sole or dominant weed in a grazing pasture or silage/hay sward, Thistlex is the most cost-effective herbicide.
Another Corteva Agriscience herbicide, it contains the active ingredients triclopyr and clopyralid, which are absorbed right down to the roots of the thistles.
Just one thistle per 20sq metres is equivalent to a 1% loss in grass dry matter.
Therefore, 50 thistles per 20sq metres, which is all too common in thistle-infested swards, can mean a drop of 50% in grass dry matter yields.
Thistles are also an animal health risk, spreading diseases such as orf, pink eye and mastitis.
For best results from Thistlex, thistles should have four to 10 leaves and be 15cm to 25cm high. They should also be actively growing.
If they have gone beyond this stage, it is best to top them and spray with Thistlex when they have regrown to the correct stage.
Apply Thistlex at 1l/ha in a minimum of 200l water and keep animals off pasture for seven days after spraying.
When spraying silage or hay swards, leave a minimum of three weeks before cutting the sward in order for the chemicals to be fully translocated to the thistle roots.