Getting the spray window of the amidosulfuron herbicide Squire Ultra just right is important in order to achieve the desired high level of control of docks and broad-leaved weeds in grassland. The key to timing is to apply Squire Ultra when the weed itself has a high level of downward systemic movement, so that the active ingredient can be taken down into the root system where it works, says Dr David Stormonth of Interfarm UK Ltd.
"Docks are very competitive weeds with large tap roots that allow survival over the winter period and rapid early spring growth. They are a real challenge to control successfully in permanent and rotational grassland. But if you get the herbicide timing right, not too early and not too late, you’ll be pleased with the result," says David.
He explains that Squire Ultra is fully systemic and it moves throughout the weed, even into the roots, albeit slowly. "Application timing needs to be just right for best results. It can be applied too early, which is when docks are starting to actively grow in the spring. At this stage weeds are using stored tap root reserves to develop new leaves and there will be an upward movement of nutrients from roots to shoots. The herbicide would also move upwards in the nutrient flow, in the wrong direction, and application should be delayed."
"The optimum spray window is when the weeds are at "dinner plate size" with expanded horizontal leaves. At this stage the majority of the nutrient flow has reversed to replenish reserves back to the root system and so the herbicide is taken into the roots which is where it needs to be. In effect the herbicide piggy backs the weeds own translocation system. Soil moisture is also important at application."
"At the end of the spray window, application can also be too late when stem extension takes place and the docks have seed heads and overlapping leaves and the flower stalks are starting to grow. Then the systemic flow in the docks reverses again to an upward direction to feed the developing flower stalks and seed heads. At this time it is best to cut the docks and treat regrowth when appropriate."
David points out that Squire Ultra does not affect white clover and can be applied to seedlings from the one or two trifoliate leaf stage onwards, with absolute crop safety. "Other products might control docks but they wipe out the white clover," he points out.
Squire Ultra contains 75% amidosulfuron formulated as a Water Dispersible Granule and is packed in a 240 grams pack. It is recommended on grassland for the control of docks, cleavers, charlock, Shepherd’s purse and field forget-me-not at a dose rate of 60 g per ha. It should be applied when docks are at a suitable growth stage between the 1st of February and the 30th June in rotational grass and between the 1st February and the 15th October on permanent grass. It has no LERAP and is safe to white clover. Keep livestock out of treated areas for at least 7 days after treatment and until foliage of any poisonous weed such as ragwort has died and become unpalatable. Do not cut for hay or silage for at least 21 days following treatment.
