Field choice is key as oat growers lose grassweed herbicides

Oat growers are being advised to carefully consider their grassweed pressure, as approval changes have meant there are no grassweed herbicide options this coming season.

Up to now, several options such as diflufenican have been available through extensions of authorisation for minor use (Eamus).

But according to Hazel Doonan, head of crop protection and agronomy sector at the Agricultural Industries Confederation, the Chemical Regulations Division of the HSE is in the process of removing Eamus for major crops.

This particularly affects oats, as growers rely on Eamus for straight diflufenican (such as Hurricane) and diflufenican + flufenacet mixes (such as Liberator).

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As ProCam head of crop production Mike Thornton points out, this leaves farmers without any grassweed herbicide options in oats.

The only exception is one product that can still be used in seed crop oats, as this is still considered a minor crop.

For some growers, particularly those with grassweed issues, it may mean it’s unrealistic to grow the crop at all this season, and instead they will have to wait to see how the situation develops.

However, some farmers may stick with the crop, especially those with no grassweed problems and a diverse rotation with leys, as weed pressure will be low.

Mike says field choice will be very important and he advises selecting cleaner ones such as those with no or very low historic grassweed populations or fields where good grassweed control was achieved in the previous crop (such as from propyzamide in the previous winter oilseed rape crop or winter beans).

Selected fields must also be easily worked, and free-draining to discourage blackgrass.

Drilling later will help reduce weed levels through the effective use of stale seed-beds and glyphosate.

There may be time to do multiple flushes, but don’t go too late, as late-drilled oats can struggle and will be less competitive.

Growers should also consider upping seed rates to establish thicker crops, but thick crops can reduce oat specific weight and increase crop height.

This can heighten lodging risk, although oats do respond to plant growth regulators, so this may be a trade-off.

Finally, consider waiting until spring and plant spring oats instead – a more vigorous crop and spring planting should lessen the burden from weeds such as blackgrass.

However, this will come down to market acceptance of spring varieties, he says.