8 March 2002

Scots early spray OK…

By Andrew Swallow

AN early fungicide to clean up forward wheat and barley will pay in Scotland, says SACs Simon Oxley.

Mildew and rhynchosporium are present in many winter barley crops and a clean up fungicide should go on as soon as sprayers can travel, he says. Wheat growers may need to consider a four-spray fungicide regime.

"Effective control of rhynchosporium is very difficult, thats why you want to start with a T0 (in barley)." Corbel (fenpropimorph) will burn out both diseases and mixing with Unix (cyprodinil) will protect new growth from both diseases and eyespot, he says.

Growers should not rely too heavily on varietal rhynchosporium resistance ratings, he adds. "They can be a little unreliable – under high disease pressure a variety rated 7 or 8 can still get the disease."

Mildew is also present in some wheat crops and the eyespot risk is high. "Prochloraz is cost effective at T0 on eyespot, or you could use Unix. If it is on before mildew becomes a problem it will also provide some mildew protection."

If mildew is the sole target then Fortress (quinoxyfen) is preferred for protection, or mixed with a morpholine such as fenpropimorph (as in Orka) if existing disease needs knocking out.

"Straight Fortress will protect the emerging leaves, but it has no eradicant activity at all," he notes.

For many wheat growers, going at T0, GS25-30 timing will effectively commit them to a four-spray programme, he acknowledges. However, given forward crop growth and high disease pressure that investment should pay this season.

"There were a lot of crops sown early and we have had a mild and wet winter. Watch them like a hawk for disease and be prepared to go in early with a fungicide." &#42

SCOTTISH CEREALS

Many forward crops.

Disease pressure high.

Rhynchosporium, mildew, and eyespot main threats.

Watch and react as soon as can travel.