Autumn spraying key to grass weed control

Prioritising herbicide applications on newly drilled grass leys this autumn will be more effective than waiting until the spring and hold potential saving for farmers.

The control of seedling weeds and especially docks during the establishment of a new ley is often overlooked, but Wynnstay’s Crop Protection Manager, Dr Simon Pope, says the solution is autumn herbicide spraying.

“Preparing the perfect seedbed for drilling grass seed is also providing the perfect conditions for weeds to germinate and grow. By striking now, it’s possible to get 100% dock control, and get on top of any chickweed problem, to reduce the weed seed bank.

“By the spring, it’s often too late since weed competition has already resulted in ‘gappy’ leys,” he says.

“Some farmers believe this to be a more expensive approach, as the weed problem doesn’t appear to be as prominent. But it could actually save you money, as you take the weeds out before they affect the establishment of the sward, and you may be able to look at different products and rates.

“A weed only has to be killed off once, so shouldn’t require a second application in the spring unless there is a persistent problem,” adds Dr Pope. “In my experience, once farmers have seen the benefit, they’re converted.

“Timing is crucial, and herbicides should only be applied once grass plants (and clover plants if present) have reached at least the 3 leaf stage. Roughly speaking, this is about one month after drilling, so there isn’t long to wait.”

There are a couple of considerations when deciding what to apply in the autumn, says Dr Pope.

“The age of the ley and the presence of clover needs to be established before any herbicide recommendation can be made. Depending on the age, there are restrictions over what can be applied, and clover presence limits the herbicide choice.

“If there is a history of a particular weed problem such as docks or chickweed, then I would prioritise the control of this over the inclusion of clover in the mix. You can easily add clover to the ley at a later date,” he explains.

There are many benefits to be seen from autumn weed management, including reducing the herbicide bill.

“Not only is 100% control of seedling docks achievable, but also the new sward gets a good, clean start without weed competition, so sown species persist for longer. The approach needs to be farm specific in terms of the product recommendations, but autumn herbicide applications to establishing newly-sown leys are now seen as best practice for many reasons.”

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