Minimal tillage chance to win grass weed war
Dont go over top on wheat
BEWARE of going for "wall-to-wall" wheat this autumn, warns Ted Bird of West Country Grain marketing co-op and manager of Cannington Grain store, Somerset.
"With such a lot of linseed grown this year it will be tempting to follow it all with wheat. But think carefully first. What effect will all that extra wheat have on the price of next years crop? And what will you follow all that wheat with?"
Now is the time to consider other break crops, he says. "Sit down, be businesslike and work out a plan. It is surely better to farm well than to try to farm the system and then come unstuck?" *
Lists good value?
DO the UK recommended lists for cereals give good value for money?
That is the question a new independent review commissioned by the Home-Grown Cereals Authority aims to answer.
"At present HGCA spends about £1m of levy payers funds on independent variety evaluation, so it is vital we ensure the money is spent wisely," says Graham Jellis, research director at the HGCA.
The review will be led by Roger Plumb, former deputy director of IACR-Rothamsted. Industry views should be sent to Prof Plumb, IACR-Rothamsted, Harpenden, Herts AL5 2JQ (Fax: 01582 760981) e-mail: roger.plumb@bbsrc.ac.uk *
DNA malting check
NEW HGCA-funded DNA fingerprinting tests developed by the Scottish Crop research Institute are beginning to unravel the complex gene interactions controlling barley malting quality. The technique is said to offer breeders the potential to select for malting performance without introducing unwanted characteristics. *
Minimal tillage chance to win grass weed war
The latest article in our
Grass Weed Action 2000
initiative, supported by
herbicide manufacturers
Monsanto, DuPont and
Cyanamid, examines one
advisers view of the changing
role of minimal cultivations.
Andrew Blake reports
KNOW your enemy, remember cultivations role and be prepared to use sequences and mixtures of robust herbicides if you hope to win the war against grass weeds.
That sums up advice to cereal growers this autumn from Masstock Arables technical manager, Clare Bend.
Minimal tillage has a key role to play, she maintains. Far from re-creating the grass weed problems of the 1970s caused by direct drilling, it gives growers a great chance to win annual battles and so eventually the war on grassweeds.
"It allows you to get blackgrass especially up and out of the system by using shallow stubble cultivations and a total herbicide pre-drilling. It is also good resistance management. Our Crop Technology trials show rolling stale seed-beds can boost blackgrass germination for subsequent desiccation by 50%.
"But you may not see an immediate short-term gain," she warns. "It does take courage and commitment because you can get higher than normal germinations in years one and two."
But moves to early sowing reduce scope for stubble cleaning. "And if you suspect or know you have resistance, you may have to think about delaying drilling." Rotational ploughing remains useful, but growers should work more shallowly in successive seasons, Mrs Bend suggests. "If you operate at the same depth you can bring up to 30% of seed shed one year back to the surface the next."
Whatever the primary cultivation, seed-bed quality has a big impact on herbicide performance. "How you achieve it for good, rapid competitive crop establishment is an over-riding factor."
Although isoproturon herbicide still has its advocates, Mrs Bend considers it has only limited uses, mainly in combination with pendimethalin (as Trump) which extends its broad-leaved weed control and persistency against blackgrass in wet autumns.
"We prefer pendimethalin-based programmes, and in terms of blackgrass control Lexus is streets ahead of ipu." In particular she favours Lexus Millennium (flupyrsulfuron + thifensulfuron) + Stomp after trials last autumn.
On susceptible blackgrass a 100g + 2litre/ha mixture gave 98% blackgrass control. Ipu at the full rate of 5 litres/ha on the very wet soil managed only 17% control, compared with the 50-60% typically expected, she notes.
"The other advantage of Lexus Millennium + Stomp is that you can spray earlier, at the 1-2 leaf stage of the weed and so avoid the risk of not getting on." On resistant blackgrass near Swindon a 100g + 1 litre/ha mix applied then left only 7% uncontrolled. By comparison full rate trifluralin/ipu at the same stage gave only 72% control.
Trifluralin is a "cheap and cheerful" component largely superceded by the likes of Lexus. Granular Avadex (tri-allate) gives blackgrass an extra knock and also has some activity against brome, she says. "But crucially it must go on before blackgrass emergence and preferably within 48 hours of drilling."
Lexus, however, cannot be used on barley. "Blackgrass control in winter barley with residuals can be a struggle, though the crop is usually more competitive than wheat."
Dagger (imazamethabenz-methyl) plus Stomp or Merit (pendimethalin + simazine) at the 1-2 leaf stage of blackgrass has shown some promise. "It is not outstanding, but it is crop safe and offers a good base for applying contacts later on." *