East: Pests and blackgrass keeping us busy

At the time of writing we have had one good frost, but the forecast suggests further wet and mild conditions. Hopefully this will not mean a repeat of last winter’s weather.

Aphid pests and barley yellow dwarf virus (BYDV) continue to be a risk despite numbers caught in suction traps falling. With temperatures around 11?C aphid flight will continue and reproduction will continue whilst temperatures are above 3C so follow up insecticides are required to most cereal crops.

Wheat after oats that has suffered from frit fly has received a chlorpyrifos application, with higher risk situations being stubbles that were min-tilled due to more trash on the surface. Slugs have also been causing issues on well tillered plants and also second wheat.

The blackgrass battle has been relatively promising and residual herbicides are performing very well. Additional residual herbicides consisting of a further 120g/ha of flufenacet plus either pendimethalin or prosulfocarb have been applied to add to top up the residual activity. Where blackgrass has grown away from the residual, the flufenacet partner is Atlantis (iodosulfuron + mesosulfuron), with the emphasis being put on good application conditions.

The application window to apply Atlantis at this time of year is very narrow, but it is crucial to apply to a dry leaf and allow time after application for it to be taken up, therefore not applying too late in the afternoon. Boom height, forward speed and nozzle selection will all contribute to effective control.

Winter oilseed rape has put on considerable growth over the last few weeks and most crops are now receiving a fungicide, with phoma symptoms visible over the past few weeks. Some flea beetle larvae can be found in leaf petioles and activity is only likely to decline when temperatures drop below 3C. Following earlier insecticide applications, the residues on the leaves can control susceptible larvae that move over the leaf surface, but with resistance in the adult beetles larvae control may well be very variable.

With soil temperatures around 10C and falling we are at the start of the propyzamide application window in OSR. The persistence of propyzamide is greater in cooler soils, so to ensure greater persistence applications will be made towards the end of November once soil temperatures are around 8C. This should ensure persistance of the active through into February.

Winter beans have been planted in good conditions, although warmer soils have caused concerns about the persistence of propyzamide. Where possible applications have been delayed longer than normal after drilling, but with rapid germination this requires careful monitoring to ensure applications are still pre-emergence of the crop.

Land destined for spring cropping has been managed and regular shallow cultivations has resulted in several stale seed-beds and large populations of grassweeds being controlled. Time will tell as to how much of a dent we have made into the weed seed bank.

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