North: Flea beetle hits Yorkshire oilseed rape crops

The forecast for odd showers last week turned out to be between 25-45mm in just over 24 hours. The rain has provided a welcome boost to oilseed rape, which was ready for a drink, but it has made some yet to be drilled heavier land quite wet underneath. However, a good forecast at the time of writing should soon see a lot more land drilled.

Oilseed rape is mostly at the 3-4 leaf stage, but ranges from cotyledon to 7 true leaves. Early sown crops look particularly well. For many farms flea beetle has been a real problem this year, with multiple insecticide applications required. It has begun to feel like blight spraying in potatoes where weekly applications are required to keep on top of the flea beetle. Despite using insecticides with different modes of action, there will be a huge selection pressure in favour of resistant flea beetle, so controlling this pest in future is likely to become even more difficult.

Clethodim is being applied to oilseed rape crops to control blackgrass. Weather conditions are ideal to get maximum efficacy from this herbicide.
Aphids being found on oilseed rape crops are very low at present and so far have not warranted specific control. Leaf miner damage is easy to see in early sown crops, but unusually this is a case where the damage looks worse than it actually means in terms of risk to the crop. No phoma has been seen yet, but be on the lookout in the coming weeks.

A lot of winter wheat was drilled in late September into good seed-beds which were rolled. Thankfully the recent rains will have provided some welcome moisture for the residual pre-emergence herbicides to work more effectively. Stale seed-beds have been particularly effective and those that have been patient to hold back from drilling will have the added benefit of moisture for the pre-em herbicides to work well.

Slug pressure so far has been low, but activity has certainly increased especially in fields sown after oilseed rape. High numbers of gout fly eggs have been seen in early sown crops and over a wider geographic area than usual. Calm and warm conditions during the last two weeks of September have been ideal for this pest to lay a lot of eggs. In some cases an insecticide has been required to try and provide some control before the larvae enter the plant.

Most winter barley has now been drilled and with so few options available for post-emergence blackgrass control every effort has been made to get good seed-beds and apply the pre-emergence herbicide in optimal conditions.

Winter bean drilling will soon be underway. The bean crop is carrying a “feel good factor” after fantastic yields this year and it often deals with the “Greening” requirements in one fell swoop. Add to this the fact that it does not suffer from flea beetle and provides some alternative chemistry for blackgrass control then beans will still be popular despite the poor prices currently. Pre-emergence herbicides are critical for both grassweed and broad-leaved weeds, the latter having very few options available post-emergence, so achieving a good seed-bed will help to get the best performance from the residual herbicide mix.

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