High disease pressure in winter barley crops means growers should consider treating susceptible varieties with an early fungicide, says agronomy firm Hutchinsons.
Mild, wet weather has favoured the spread of several diseases in early-sown crops across much of the UK – particularly net blotch, rhynchosporium, powdery mildew and brown rust, says technical development director David Ellerton.
Risk has been compounded by the large area of spring barley grown last season, which resulted in more barley volunteers emerging this autumn, from which infection can transfer to the new crop, he says.
“This combination of more inoculum on volunteers alongside mild, wet conditions, has been perfect for autumn barley diseases, although later drilled crops generally aren’t as badly affected.”
The situation is worst in varieties with low disease ratings of 4 or below – and where there are a lot of volunteers from previous winter or spring barley crops. Manganese deficiency can also make crops more susceptible to mildew infection.
Dr Ellerton says this increased disease risk may be enough to justify an autumn or early spring fungicide application prior to stem extension, to prevent disease infections reducing the crop’s tillering capacity and yield potential.
Yield responses of over 0.5 t/ha could be possible, says Dr Ellerton. Products containing prothioconazole will give the best control of net blotch, rhynchosporium
and mildew. Additional tebuconazole will be necessary for brown rust.
“These products should generally be applied at half to three quarters dose depending on disease pressure.”