dare YOU GO lower?
How should wheat management best be adapted to make the most of Agenda 2000? One large supply company is finding out, as Gilly Johnson reports.
IT SOUNDS like a contradiction in terms: a seed supplier investigating low seed rates. But thats just what Mike Jeffes of Dalgety Arable is up to at the companys trial site of Throws Farm, near Dunmow in Essex. Agenda 2000 is his motivation; hes confident it will mean a large increase in winter wheat. And with the continuing trend towards larger units managed by fewer staff, thats going to bring problems for growers who will be forced to extend the autumn drilling period in order to cope.
Earlier drilling, and so low seed rates, will become the norm, he suggests. "But its not a straightforward change. Some varieties are not suited to early drilling, and some varieties are not suited to low seed rates."
The Dalgety trials, which include 40 varieties drilled at three different timings (4 September, 17 September and 9 October), will sort the sheep from the goats. Physiological development is being checked through the season. Already at the end of February, some varieties such as Chablis were racing towards growth stage 31 in the early drilled plots. Cantata was also showing fast development.
As a low vernalisation wheat, Chablis is an extreme case, says Mr Jeffes. But even the classic winter varieties such as Consort, Equinox, Riband, Spark and Buster were looking well ahead in the early drilled strips. "Its easy to underestimate the impact of early drilling on plant development," he warns.
"Wheat plants produce leaves as a response to accumulated temperature. So early drilled plants grow more quickly, because there is more heat about. For every third leaf that appears, a tiller is produced. Its temperature, not plant density, thats the trigger.
"But you need to keep the seed rate lower to ensure that each tiller will be strong enough to support an ear without lodging, and isnt crowded out."
Many growers have been experimenting with low seed rates but without the backing of variety trial comparisons, says Dr Jeffes. "Were aiming to be able to give precise advice on best sowing dates and seed rates for the whole range of varieties, so that growers can plan a drilling schedule and give the right varieties the most appropriate slot in the programme."
Seed rates and drilling dates have been varied across two contrasting varieties – slow developing, high tillering Claire and fast developing, shy tillering Buster. Seed rates are:
l 100 seeds/sq m (extremely low)
l 200 seeds/sq m
l 300 seeds/sq m (nearer the conventional rate)
Drilling dates are:
The thinking is that Claire would be more suited to early drilling than Buster – but will this be borne out by results? The trial is being repeated in Yorkshire to give regional information.
"We would have liked to go even earlier if we could have done, but the season was too wet," says Mr Jeffes.
Overlaid on this trial will be the root stimulant treatment Axis. "This should have most effect on the later drillings, at the lower seed rates." Four seed treatments are being compared:
l a single purpose product, Sibutol
l experimental product triticonazole
l fluquinconazole, the take-all and foliar seed treatment from AgrEvo expected to be available for drilling this autumn, subject to approval.
Disease control will be another factor to consider with early drilling, says Bob Bulmer, national technical co-ordinator with Dalgety Arable. Experience with new seed treatment fluquinconazole is persuading him that this could be a useful tool in holding back disease where crops are drilled early.
Even in February, the fluquinconazole seed treatment was showing septoria disease control. Basal leaves on the untreated plot of Buster had tritici spores – none were visible on the treated plot, "This product looks effective against take-all, eyespot and early septoria, which would make it ideally suited to early drilling," says Mr Bulmer. "But whether its worthwhile will depend on how much it costs…."
Developmental stage in early Feb
Sowing date 4 Sept 17 Sept 9 Oct
leaves/tillers leaves/tillers leaves/tillers
Abbot 5/5 4/3 3/1
Brigadier 5/6 3/4 3/1
Buchan 4/3 4/3 3/1
Buster 4/6 3/3 3/2
Cadenza* 5/3 4/3 3/2
Chablis** 5/5 3/3 3/2
Charger 5/5 4/4 3/1
Claire 5/6 3/3 3/2
Consort 5/4 3/5 3/2
Equinox 4/7 4/5 3/2
Hereward 4/5 3/4 3/1
Hussar 4/5 3/4 3/2
Madrigal 5/7 3/3 3/1
Malacca 4/7 3/5 3/1
Reaper 4/4 3/4 3/1
Rialto 4/6 3/4 3/2
Riband 4/5 3/4 3/2
Savannah 5/5 3/4 3/2
Shamrock 4/4 4/3 3/1
Shiraz** 5/7 3/3 3/2
Soissons 4/4 4/4 3/2
Spark 4/5 3/5 3/2
* at growth stage 30, stem extension ** at growth stage 31, first node
Source: Dalgety Arable