Published on 27/09/2022
If every Yellow Bristle Grass (YBG) seedhead contains an average of 90 seeds, and a single plant can have up to 60 seed heads, how many plants need to set seed in your farmers’ paddocks before they have a big problem? The answer is, not many.
Add in the fact that YBG seed passes through the rumen unscathed and can survive up to three months in dairy effluent, and it’s easy to understand why all the experts tell farmers the same thing – if it’s on your farm, whatever you do, don’t let YBG set seed.
Fortunately, Dockstar herbicide from Nufarm makes it easy to achieve this, helping stop the spread of YBG in valuable pastures. And soon, it will be the ideal time to use it in paddocks known to be infested, says Nufarm technical specialist Paul Addison.
Left uncontrolled, YBG can have a massive annual seed set, because cows don’t willingly eat it. Researchers have counted up to 20,000 seeds per square metre in severe YBG infestations, ranging down to 5-10,000 seeds per square metre under light infestations.
Techniques for reducing this risk include early mechanical topping (before viable seeds are set); heavy grazing, or chemical control with a herbicide, and this is where Dockstar comes into its own, Addison says.
Applied after YBG has emerged from the ground, but before seed heads are visible, Dockstar has proven very useful for controlling YBG by stopping it from setting seed.
And it comes with an important benefit: It has no grazing withholding period.
As a result, Addison says, sprayed paddocks can still remain in a grazing rotation as short as 21 days. Up until now, the earliest return time for paddocks sprayed for YBG control has been 28 days, with a further seven days required between grazing and spraying.
Dockstar also requires at least seven days between grazing and spraying, plus a gap of at least 14 days after spraying to the next grazing.
Paul Addison says a 21 day return time is easier for farmers to fit into their typical early summer grazing rounds.
Recommended rates for Dockstar are 1.5-2.0 litres per ha, with no adjuvants or other products added to the herbicide.
“Our trials have shown this gives excellent, cost-effective control of YBG, with consistent results year to year,” he says.
After spraying, Dockstar is likely to cause temporary yellowing and growth suppression of some pasture species, including ryegrass and clover.
Keeping stock off treated paddocks for at least 14 days after application allows the active ingredient in Dockstar (asulam) to take maximum effect on YBG, and minimises any check to pasture growth.
Addison says it’s very important that farmers learn how to spot YBG at the right time for spraying, because Dockstar will not kill plants that have started to produce seed-heads.
“They need to start monitoring early, during pasture walks from mid-November onwards, once soil temperatures have reached about 16-18°C.”
“Seed heads are easy to spot, but identifying the weed as a young plant can be more difficult – remind your farmers to look for a flattened, hairless leaf sheath; long hairs at the base of rough-edged leaves and reddish-purple colouring at the base of the sheath.”
Meantime, if you want to make an early start on helping your customers get the better of YBG, talk to them now about keeping their pastures in good shape through spring and into early summer, Addison says.
“One of the key recommendations for best practice control and management is to encourage better pasture competition at the time of year that YBG germinates, between October and December.”
“By reducing or avoiding pasture damage before and during the period of YBG germination, there are less likely to be bare patches where YBG has enough space and light to take hold.”
For more detail, contact your Nufarm territory manager.