Farmers looking to maximise grassland performance should put weed control at the top of their lists.
Farmers could benefit considerably from adopting a continuous weed control strategy, instead of a reflex reaction to make the farm look a bit better when docks get out of hand.
According to results from a Nufarm farmer survey, only half of farmers did some kind of weed control, and of those, 18% viewed the task as simply ‘tidying up’.
Brent Gibbon, of Nufarm, believes farmers are missing a trick by not recognising the benefits to grassland productivity.
Mr Gibbon adds: “Rather than looking at it cosmetically, farmers need to look at weed control for the return on investment and the extra dry matter.”
Considering every 1% increase in weed cover will result in a 1% decrease in grass growth, addressing a 10% dock infestation could increase a yield from 10 tonnes to 11t dry matter/hectare (4t to 4.5t DM/acre).
This enables improved grazing availability and high stocking rates to deliver a ROI of 14:1. Mr Gibbon adds that this ROI does not include the fact grass quality will improve due to less, lower feed value weeds. Consequently, the financial benefits could be even greater.
“Weed control is one of many factors grassland farmers need to get right. If you miss it out, it can be disastrous, especially in a reseed,” he adds.
To achieve the best ROI possible, there are some key areas to think about when spraying established grassland:
Weeds need to be actively growing to enable the herbicide to be taken up by the plant. In very dry conditions, it is worth holding off on weed control until the plant starts to grow again.
Timing is everything. Apply too late or too early and weed control will not work effectively, if at all.
Most farmers spray weeds in spring, when weeds are actively growing.
However, August-September is an excellent time for weed control as weeds are often at their leafiest and unlike in spring, the plant is not trying to put up a seed-head.
Those farmers who were unable to apply herbicide in the autumn of 2018, will need to pay special attention to weeds this spring and may need to spray more than usual.
Assess swards in early March to ensure you have time to prepare, choose the right product and plan for timely application. Look at the percentage of dock cover and other weeds.
Chickweed can sometimes keep growing through winter and, like docks, prefer high fertile soils.
A minimum 200-litre water volume per hectare is needed to give good coverage on the weed leaf, especially in dense swards.
Air inclusion nozzles on sprayers are also recommended. This will give optimum control and achieve good coverage of the weeds.
On multi-cut systems, where silage is being cut about every four weeks, weed control can be difficult as it takes about two weeks for the weed to get to the optimum leafy stage for spraying and three weeks to achieve the maximum effects of the herbicide.
A three-week cutting withdrawal period also needs to be considered.
As a result, those farmers doing multi-cut, should consider spraying weeds in August/September. The herbicide then has the whole of autumn to translocate.
Choose a clover safe spray and apply when clover has at least one trifoliate leaf.
385 grassland farmers were surveyed on their views of weed control:
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