25 July 1997

Treated seed good insurance – NIAB

TREATING seed with Baytan (fuberidazole + triadimenol) could help prevent yellow from rust running out of hand next spring, according to recent results from a NIAB trial.

Despite severe disease pressure Brigadier treated with Baytan was protected long enough for spring spraying to be deferred for several weeks.

Baytan treated plants showed 1.1% infection in early April, rising to just 1.4% by second node detectable (GS32). By contrast untreated plants showed 2.8% infection at the first date, and 6.3% by GS32.

Although rust can be controlled by sprays alone, paying £85/t for Baytan-treated seed insures against changeable weather and allows sprays to be timed more accurately for other diseases like septoria, says Bob Simons, agronomist for manufacturer, Bayer.

It also lets growers reduce the gap between first and second sprays. Allowing that gap to grow too long this spring contributed to the widespread yellow rust problems, he believes. "Crops grew very quickly after first sprays were applied, resulting in a lot of fresh, unprotected growth."

NIABs Phil Stigwood conducted the trial and reckons that Baytan will help growers cope with a potential massive source of inoculum this autumn, most notably from Brigadier volunteers in set-aside.

Controls early infection

"We have seen over the years that Baytan does control early infection. Yellow rust must be kept out early in the season, control is then relatively straightforward.

"If it establishes between November and March, a few mild spells allow it to get going. It does not matter how dry the weather then becomes. Given a few dews to allow spores to germinate, yellow rust will spread rapidly." &#42

Robert Harris