South: Careful canopy management required

Rain, wind and more rain means little work has been possible over the last three weeks. Winter wheat is at GS 29-30 and is ready for T0 fungicides, while winter barley is at GS 28-29 and nearly ready for the T1 fungicide treatments.

A large number of fields require blackgrass treatment and some fields also require broad leaved treatment – it seems like we are going to be very busy over the next few weeks. Be careful not use complex tank mixes for fear of crop damage.

This year the situation is made worse by the fact that only one named product may be mixed with Atlantis (mesosulfuron + iodosulfuron). So if you wish to mix a T0 fungicide with Atlantis make sure it is one of the permitted fungicides. When considering the T0 fungicide make sure the disease resistance profile of each variety, especially yellow rust and septoria is considered.

Oilseed rape is at the green bud stage and it will soon be at the stem extension stage requiring the nitrogen dressing. Carefully assess the leaf area index (LAI) at the stem extension stage to work out the amount of nitrogen fertiliser required to achieve a leaf area index of 3.5 at the mid flower stage.

Remember an over large canopy will lead to lower yields due to poor photosynthesis by lower layers of pods. Crop canopies with a LAI greater than 1 will benefit from the use a PGR fungicide such as Caramba (metconazole) or Folicur (tebuconazole) applied at the yellow bud stage.

Spring barley and linseed crops drilled ten days ago are just coming through the ground, albeit looking a little pale because of two sharp frosts last week. Spring beans are at the cotyledon leaf stage and have some leaf notching symptoms from the pea and bean weevil attack. On the plus side most crops have quickly greened up and now growing fast, making up for the lost time during cold weather. Peas that have been awaiting drilling because of wet soils will hopefully be drilled this week.

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