South: Pre-emergence treatments working well

The weather over the last month has allowed most outstanding field work left to be completed.  Cereal drilling, except the odd field after maize, is complete. Due to the wet spell, crops fit into two categories: those drilled recently that after the cold spell are only just emerging; and the earlier drilled crops that are starting to tiller in places.

Unless the autumn stays unseasonably mild and open, it is unlikely that emerging crops will get a follow-up treatment for blackgrass this autumn. In most cases, the large flushes of blackgrass taken out before drilling, combined with good seedbeds and moist conditions, have ensured that most pre-emergence applications are doing a good job.

I would estimate that only 25% of my earlier drilled crops have got enough blackgrass in them to warrant an application of Atlantis (iodosulfuron+mesosulfuron) or Horus (mesosulfuron + iodosulfuron) this autumn. These applications will go on in the next two weeks time. The remainder will just recieve an insecticide for barley yellow dwarf virus control.

Application conditions need to be good to maximise the efficacy of these treatments. For best results, Atlantis needs at least two hours post application before rainfall or a heavy dew, so avoid the temptation to apply that last tankful at twilight. Also, pay attention to forward speed (max 12kph) and spray quality to ensure good coverage.  

Oilseed rape crops have now all had a phoma spray and any follow-up sprays are two to three weeks away. Most of the earlier applications of Aramo (tepraloxydim) have worked fantastically well on the blackgrass, showing that target site resistance, in this area at least, is not as bad as we perhaps feared. 

A second flush of blackgrass is appearing in some oilseed rape crops and Kerb (propyzamide) will be used as appropriate later on this month once soil temperatures have dropped below 10c.

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