26 May 1995

Get flag-leaf sprays on now – ADAS

WHEAT growers who have not yet applied their all-important flag-leaf fungicide sprays should do so now, urges ADAS.

Recent rainfall – in places twice the normal average – has raised septoria risks significantly.

This means crops sprayed at GS32/33 (second/third node detectable) in the hope of delaying the main fungicide until ear emergence will probably need treating soon after full flag to ensure adequate disease protection.

Many fields were due to be sprayed this week. But a feature of the season is the wide spread of development, says Cambs-based John Garstang. That means some growers, especially in the north, can still make timely applications.

Although newer fungicides give longer protection than older chemicals, high risk varieties should be treated as soon as possible, he says. "Now is the time for action."

Growers who omitted an earlier spray can ill afford to cut dose rates, says colleague Peter Gladders. "There is yellow rust around and our forecast is that the risk is higher than last year."

Serious disease

There is also concern over brown rust, a "serious" disease which can develop quickly in warm weather, as happened two seasons ago, he warns.

In North Humberside ADASs Brendan OConnor has the following reminder. "If you could only apply a single fungicide spray to winter wheat then GS39, flag leaf ligule/collar just visible, would be the most profitable timing."

Most winter barleys should have had a spray against brown rust by now. Many came into ear earlier than usual increasing the length of protection needed says ADAS. Crops are generally clean, but the wet weather could trigger rhynchosporium.

Spring barley fungicide spraying is in full swing in the south. "Weve had no disease," reports Steve Cook of Hants Arable Systems. "But with humid conditions there is always the potential for rhynchosporium." Cutting doses too hard could prove false economy this year, he suggests. "Spring barley should be worth a bit and it looks good. Well probably be sticking to three-quarter rates."