Farmers Weekly Interactive

South: Phenomenal amount of blackgrass

Most oilseed rape crops are growing with fury like it was spring and are at the eight leaf stage. These crops will need a PGR fungicide treatment based on metconazole or tebuconazole if not already done so. Ensure to use a fungicide that also delivers a punch of phoma treatment as, since the last seven days the risk of this disease has increased much because of the recent rains and the higher than normal seasonal temperatures.

 

The early drilled winter wheat and barley crops are at the four leaf stage. So far slugs have posed little or no problem, but rain has brought up these dreaded creatures and there seems to be significant damage in some fields, particularly those just emerging (late drilled fields) and where the seed-beds are cloddy.

 

Check crops carefully and apply slug pellets as soon as soon as conditions allow, but remember the maximum single application doze of 210g/ha and 700g being the maximum dose per calendar year for metaldehyde.

After 25mm of rain, there is now a phenomenal amount of blackgrass present in fields of both wheat and barley, this is especially so in fields where a non inversion cultivation technique has been adopted. It is now imperative to apply Horus (iodosulfuron + mesosulfuron) plus a residual as quickly as possible before the frosts arrive and the blackgrass stops growing actively in the wheat fields.

 

Alas! In barley the options are rather limited and the results may be disappointing. Use either a material based on chlorotoluron, variety permitting, or Axial (penoxaden). Be very wary in the soft barley crops and avoid frosty conditions to minimise lasting damage particularly when using Axial and especially in mixtures with insecticides.  

 

The trapping results have been indicating that there are a large number of aphids present this year in oilseed rape and cereal crops. The seed dressings will be running out of steam about now in the early drilled fields and there may be a need to apply a pyrethroid aphicide to further protect against barley yellow dwarf virus in cereals and turnip yellows virus in oilseed rape.

 

Susceptible varieties of winter wheat are showing active pustules of mildew, mainly due to the mild weather. This should not need any attention unless in late-drilled fields. Cabbage stem flea beetle larvae are visible in some fields of oilseed rape.

 

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