South: Tackling disease in cereals and OSR

We had 6mm of rain last week and another 7mm two weeks before that. This has helped green up crops, particularly the winter barley which was beginning to look very yellow.

Nitrogen has been applied to winter barley and oilseed rape, which should start to grow rapidly now that temperatures are rising.

Winter wheat crops are carrying a lot of septoria on the lower leaves and Claire and Solstice have mildew present. As the T0 fungicide timing approaches at GS30, consider applying a triazole fungicide with a broad-spectrum activity.

Winter barley crops are at GS28 -30 and in about 10 days time should be approaching GS31 when the T1 fungicide will need to be applied. A fungicide such as Jaunt, which is based on prothioconazole + fluoxastrobin + trifloxystrobin would be a good choice.

The addition of the strobilurin component will help improve net blotch, rhynchosporium and rust control . Make sure at least a 50% to 60% doze is used since the earlier T1 timing is more important for disease control in barley.

Oilseed rape is at the stem extension to yellow bud stage. A large number of pollen beetles have arrived and are at the threshold level 15 beetles per plant in many fields.

If the threshold levels have been exceeded then a pyrethroid product such as Markate (lambda cyhalothrin) or Biscaya (thiacloprid) can be used. The latter is effective against the resistant type of pollen beetle.

In dense crops where the green leaf area (GAI) is expected to exceed 3.5 then a plant growth regulator fungicide should used to hold the crop back. This is also the time to consider the threat of sclerotinia and an appropriate fungicide such as Galileo (picoxystrobin) or Filan (boscalid) should be sprayed, depending on the weather.

Remember that all the sclerotinia fungicides are protectant only and therefore need to be sprayed before the infection has occurred on petals.

Spring barley crops are now through and will need inspection for weeds which will quickly appear after the recent rain.

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