7 June 1996

Ear spray could protect wheat yields – ADAS

By Robert Harris

EAR sprays on wheat could pay more than usual this year, especially on crops which were last treated before full flag leaf emergence.

"Many growers rightly sprayed earlier than normal to prevent disease becoming established on leaf two as well as the flag leaf," explains Bill Clark, ADAS national cereal pathologist based at Boxworth, Cambs.

"It follows that those fungicides are going to run out of steam earlier, so there is more justification for applying an ear spray. Sprays up to 10 days after ear emergence can still protect yield."

Septoria tritici is the main disease worry – there are reports of nodorum and brown rust in some areas, but only at low levels.

Boost grain fill

The aim, he explains, is to maintain the green flag leaf area as long as possible to boost grain fill, rather than to specifically protect the ear. "You will get incidental control of ear diseases like sooty moulds, but targeting quality diseases like blackpoint and fusarium is very difficult."

For that reason, he suggests as a starting point a quarter rate of a more persistent triazole like tebuconazole (Folicur), cyproconazole (Alto) or epoxiconazole (Opus). "Rates should be adjusted according to the timing of the last spray. Earlier ones may justify higher rates, especially if older triazoles are used," explains Mr Clark.

Crops in the north and west, which have received more rain, are likely to give the best returns, he adds. "If this dry weather persists, many crops in other areas will be droughted out and may not be worth treating."

Those growers who were able to spray after flag leaves were fully emerged should treat crops as normal, and spray to preserve quality.

&#8226 Richard Leech, fungicide manager for Ciba, which manufactures ear wash fungicide difenoconazole (Plover), maintains crops are at risk whatever happens.

Wet weather encourages Septoria nodorum, to which both Soissons and the widely-grown Brigadier are susceptible, he says. If warm and dry, brown rust could attack susceptible varieties like Rialto, Buster, Soissons and Haven, all of which have NIAB resistance ratings of three. And drizzly, damp weather favours sooty mould development, which can affect all varieties.

Ciba work in 1995 showed marked increases in yield across a range of varieties when Plover (difenoconazole) was applied at complete ear emergence (GS59), he says. The yield boost was due to improved grain fill leading to specific weight gains averaging 1.06kg/ha (0.43 g/acre).

he claims.