West: Big problem with volunteer OSR

Justin Hayward once sang: “my life will be forever autumn” and this is certainly how things feel in the South West at the moment.  Crop growth has carried on unhindered and early November drilled wheats after grass leys are now fully emerged. 

The damp, mild weather has allowed grassweeds to emerge, especially since the last spell of heavy rain wetted through cloddy areas of strong land.  Residual herbicide performance has not been as consistently excellent as last year.

The mild conditions and good levels of blackgrass emergence means conditions are ideal for autumn contact materials and a dry spell this week should see a lot of spraying completed.  Winged aphids are being detected in cereals, therefore, an aphicide will be prudent. 

Insecticidal seed treatments on early-sown crops will be nearing the end of their useful performance so should also be treated.

Forward winter barley, particularly Cassia, is heavily infested with mildew and a lower level of brown rust.  The dirtiest crops are receiving a morpholine fungicide to preserve biomass which is a key yield driver in this crop.

Soil acting herbicides, such as chlorotoluron and pendimethalin, really need to be on winter barley by now before any grassweeds surviving the pre-emergence treatment grow too big.

Apart from grassweeds, one of the biggest problems this season has been volunteer oilseed rape.  Second wheats after rape two years ago are showing combine lines of rape volunteers and Thor at 10g/ha (tribenuron) has been added to residual herbicide mixes.

Phoma levels remain low in oilseed rape. Where treatments are only just being applied this may well be a one spray season especially given the current size of rape leaves.  Finally, I will trot out the old mantra for oil seed rape; soil is still too warm for propyzamide and carbetamide.

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