7 June 2001
Move fast to prevent barley spotting
By Andrew Swallow
APPLY spring barley fungicides to prevent ramularia and physiological spotting before symptoms are seen, advises the Scottish Agricultural College.
“As soon as the ear is out, the spots just come in, almost as if it is a growth stage trigger,” said senior cereal pathologist Simon Oxley.
“The optimum time to spray is on to a pristine crop at the boot stage.”
Forward crops in Scotland and Northumberland — areas which have been hammered by the phenomenon before — are almost at that stage now.
“Waiting for ear fully emerged could be too late to prevent yield loss,” warned Dr Oxley.
A strobilurin fungicide seems to be the key to control, said Dr Oxley.
“It does not matter whether it is Amistar, Twist or the Opus co-formulation Landmark, but it should always be in a mixture with a fungicide with another mode of action.”
All spring barley crops in at-risk areas warrant a second fungicide, believes Dr Oxley, but severity and response to treatment does vary. Chariot is most severely hit.
“Yield responses can be up to 1t/ha.” Typically a 40% dose of strobilurin plus 40% dose of partner product should be sufficient, he says.
- Barley leaf spot strategy, FWi, 09 February, 2001
- Use strobs to combat mystery leaf spot, say Scots, FWi, 03 March, 2000
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