8 September 1995

Choose lower-fungicide wheats with care – ARC

By Andrew Blake

BE careful when choosing wheats for reduced fungicide strategies.

That is a new message from the Arable Research Centres 1996 winter wheat descriptive list. It highlights big regional differences in the response of varieties to inputs, albeit after one years experiments in a low disease year.

Growers in Essex using three sprays last season would have wasted money on most varieties and been better off with a single flag leaf treatment, it suggests. But Dorset farms would have seen a three-spray approach rewarded on all but five varieties.

With results from early and late drilling trials as well as those on autumn-sown spring wheats, the 40-page booklet aims to give ARC members detailed management guidance for their own areas. Growers are far less interested in the national picture on varieties than in how they perform on their own farms or within their own area, claims director Dr Mike Carver.

A notable feature of this years trials of 33 varieties across 15 sites is how some established names, such as Riband, Beaver and Haven, which still account for much of the market, were beaten "hands down" by newer ones, he says. "Farmers should be more adventurous if they want to start improving their performance."

The new fungicide work came partly because modern, more persistent triazoles "have fundamentally changed the approach to wheat husbandry", says technical co-ordinator Nick Poole. And with farms growing in size, single-pass tactics have become more logistically attractive.

All 33 varieties were tested at four sites comparing one- and three-spray programmes. Moving to three sprays on Hereward had little impact on average yield. "We are reasonably confident it can be farmed with just one fungicide," says Mr Poole.

Riband generally responded well to three sprays giving a 9.1% mean yield increase. "But means can be meaningless," he warns. The figure masks a big range – from a cut in output of 0.2% to a boost of 20.4% depending on site.

In septoria-prone Dorset, where a 4.6% lift was needed to cover the extra fungicide cost, only five varieties – Optimist, Spark, Dynamo, Cadenza and Hereward – would have been more profitable with one spray, he says.

In Essex, where a 6% boost was required to offset slightly higher spending on yellow rust, the picture was completely reversed.

&#8226 Sowing date trials, outlined for the first time in the new ARC list, "blow a hole in the theory that early drilling boosts yield", according to Dr Carver. It all depends on location and variety, he suggests.

A range was tested in various slots. In Bedford sowing in early September cut yields by 17% on average compared with the more conventional end of September/ early October timing. But in Lincolnshire mean output was raised 14%. However, there were big varietal differences according to site – Ritmo ranging from -21% to +17%. &#42

Winter wheat

&#8226 New data on: Reduced fungicide management. Early & late drilling. Autumn-drilled spring varieties.

&#8226 Highlights regional differences.

&#8226 Early sowing no guarantee of increased yield.

&#8226 Late drilling loss range 0.6-1.4t/ha (0.2-0.6t/acre).