West: Late maize harvest delays some wheat drillings

With much of the southwest wheat crop due to be planted after maize, a late maize harvest inevitably means that the following wheat is going to be late-drilled. The more favourable maize sites have only been marginally later to harvest this year than normal. But in the more marginal areas, maize crops are weeks later than last year and at worst will never make it to the target dry matter levels at all.

Second and continuous maize crops have been severely affected by maize eyespot this year. I believe that in future maize growers are going to have to factor in a fungicide application as standard practice to control this potentially devastating disease if they are intending to grow a second or continuous maize crop on a marginal site.

Oilseed rape crops range from being well established with a very high green area index (GAI) to crops that are going to need a lot of monitoring and looking after if they are going to make it through the winter. The delayed wheat harvest has meant that a lot of rape was not planted until mid-September or even early October in some cases.

These crops are going to be more vulnerable to damage caused by phoma than the better established crops. They therefore need to be prioritised when it comes to making phoma control applications. Care should be taken over the choice of fungicide on these backward crops. Actives with a growth regulatory effect should be avoided, whilst the forward crops may well benefit from such a phoma product. Slugs will be an ever present threat to these small crops, as will pigeons, and will need monitoring to ensure that they do not succumb to either of these pests.

The wheat and barley crops have generally emerged well and have had an application of pre-emergence herbicide. There are, however, a few crops where the pre-em was not applied for one reason or another. Barleys that have not had a pre-em should receive an early post-em herbicide as a matter of urgency as once the grass weeds have got away in a barley crop we have very little in the armoury to deal with them. There are more options in the wheat crop no matter what the target grass weeds are, so they are less important than the barleys in terms of getting the job done.

Where bromes are a problem, earlier drilled crops of wheat will need inspecting soon to determine whether the bromes have started to emerge or not. I have found in the past that in some years we need to control brome well before Christmas, whereas in other years the weed does not emerge until very late in the autumn and good control is achieved by leaving control until February or early March.

Most crops in the region seem now to be planted with Deter on the seed to control barley yellow dwarf virus (BYDV). This will be satisfactory to control BYDV in most crops but some of the very early drilled crops in coastal areas have grown so much that the effect of the Deter seed treatment will have become diluted in the biomass. Therefore, a follow-up insecticide will be required to ensure continued control of aphids to prevent BYDV developing, particularly as the weather remains unseasonably warm.

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