East: Tight window for broad-leaved weed control

After many winter technical meetings it is good to be out in the fields again. Most cereal and oilseed rape crops are looking healthy. The propyzamide and carbetamide chemistry appears to be working well on the grassweeds in oilseed rape crops and all product timings are showing signs of activity.

The mid-November applications are looking particularly pleasing. In oilseed rape crops I am looking for cleavers, mayweeds and thistles. The window of opportunity for applying clopyralid and picloram, which control these weeds, may only be a few days long, so we need to be prepared. Phoma and light leaf spot may need treating in the near future, particularly as most plants are small.

Wheat bulb fly egg counts are high this year and high risk fields should have been treated with an egg hatch spray. Future herbicide applications on these fields will need careful timing to avoid crop damage from herbicides being applied to soon after chlorpyrifos applications. Most pre-emergence herbicides on cereals have worked well.

Some later-drilled winter barley crops will need to be treated with pinoxaden in spring, where blackgrass has come through the programme. This will need applying while the grass is still small (ideally less than three leaves). We eagerly await a window of opportunity to apply Atlantis (iodosulfuron + mesosulfuron) onto winter wheat.

February historically offers the best levels of control, avoids tank mix complications, and potential crop growth suppression often seen with later applications. Cereal plant populations are generally looking promising. If plant numbers are low I am encouraging an early nitrogen dressing followed by a manipulative plant growth regulator to promote tiller production. Soil test results for the soil mineral nitrogen levels are now being returned.

These are again showing high nitrogen levels after manures applied over a year ago. Although, the winter has been cold with early snow, there has been little excess winter rainfall to wash nitrogen out over the winter period. The soil mineral nitrogen tests will enable clients to fine tune nitrogen programmes taking into account this slow release organic nitrogen source which the Fertilizer Manual (RB209) does not account for.

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