Growers warned over brown rust threat.
Adas cereal pathologist Bill Clark said: "Brown rust is rarely talked about with regard to T1 spray decisions but this year is a worrying exception. With so much Alchemy in the ground we have not been surprised to see brown rust through the winter and early spring."
Judith Turner of CSL confirmed that levels of brown rust reported to CropMonitor have built up over the past couple of weeks.
She said: "Earlier in the season both brown and yellow rust were present. Recently the hot weather has favoured brown rust but yellow rust is still present so both require monitoring on farm."
Jim McVittie, HGCA Recommended Lists manager, suggested that growers would not be surprised to see brown rust on susceptible varieties such as Solstice, Cordiale, Soissons, Zebedee, Deben, Consort and Alchemy. "What is more surprising is seeing the disease on Robigus and Oakley, but low levels were detected on these varieties in the 2006 disease virulence survey so they certainly need to be watched," he said.
Mr Clark added that people were not expecting to have to deal with brown rust at this stage but spring temperatures have been so high this season that brown rust has kept going and in the last two weeks it has taken off. Therefore growers may have to change their fungicide plans quickly.
He pointed out that even where T0 and T1 sprays have been applied the brown rust may have moved up on to newly emerged leaves. Yellow rust has been reasonably well controlled but the brown rust on newly emerged leaves is very active.
Mr Clark said that this posed a problem for many farmers and advisers and suggested that some crops may require a pre-T2 spray to protect leaf 2 and leaf 3.
Further information on wheat disease control can be found in the latest HGCA topic sheet Foliar disease control in wheat ( 2007 and in the updated The wheat disease management guide.
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|Publication:||The Journal (Newcastle, England)|
|Date:||Apr 26, 2007|
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