Feed barley gets nod
Rise in number of grass weeds causes concern
by Andrew Blake
GRASS weeds have increased markedly throughout the UK, according to a Cereals 99 survey.
Over half the 230 interviewed growers, managing nearly 120,000ha (300,000 acres) of arable from Scotland to Sussex, report at least one grass weed problem on more than half their winter cereals area.
Wild oats and blackgrass are most troublesome, with 95% and 84% of farms, respectively, affected. 32% of growers have blackgrass problems on more than half their winter cereals, while 21% report similarly severe wild oat troubles.
Brome, couch and ryegrass are seen as troublesome by more than two-thirds of growers, but are much more localised and confined to less than 25% of the cereals area in most cases.
Most farms say their problems have risen over the past five years, most notably with blackgrass and brome. Indeed, nearly one-third have worsening blackgrass and a quarter burgeoning brome.
Wild oats
Wild oats are increasing on just under 20% of units, while 10% and 5% of farms, respectively, say ryegrass and couch are getting worse.
Larger units are experiencing the biggest increases in blackgrass.
Wild oats are particularly evident on smaller farms and in southern England, western counties and Wales. Scotland and northern England have seen a dramatic rise in brome, while ryegrass is proving especially troublesome in southern England, and couch in western counties and Wales.
The fact that 40-50% of growers report no easing of difficulties with any of the five main grass weeds, despite best endeavours, underlines the seriousness of the challenge.
Herbicide resistance (or poor chemical control) is seen as the main reason. Over 66% of growers interviewed consider resistance a problem. Just under a quarter say it is serious.
Resistance concern
Although most prominent in East Anglia, concern about resistance is apparent in most parts. In all regions except Scotland and northern England well over half the growers identify resistance as a current problem and about 75% feel it will become so. Even in the north, it is seen as a problem by 45% and expected to become so by more than 60%.
Post-emergence autumn isoproturon remains the most popular control chemical, being applied (generally in combination with other treatments) by three-quarters of those surveyed. But worries over the environment, resistance and poor performance in particular, mean more than half plan to use less IPU this autumn, suggesting big changes in chemical control strategies.
Ploughing is used for grass weed control by over 90% of growers, with break crops employed by 38% and spring cropping by 32%. 29% use stale seed-beds and 26% consider set-aside valuable for control.
Economics of inputs on trial
WHICH combination of seed rate, fertiliser and fungicides will extract best gross margin from winter wheat after oilseed rape on light land?
That is the question Robert Pask hopes to answer at Heydour Lodge, Grantham, with 20 Hydro Agri/ Zeneca field-scale tramline trials on the Drake. He has spent between £65/ha (£26/acre) and £166/ha (£67/acre) on the three inputs. But only harvest will tell which approach proves most economic.
Sowing rates of 100, 160 and 250seeds/sq m are being compared with his conventional 375, the low rates going in on Sept 3, the conventional at the end of the month.
"A single BYDV spray didnt master the problem on the early drillings," says Mr Pask. In future seed treatment may be needed.
All drillings received 40kg/ha (32 units/acre) of N at GS23 (main shoot plus three tillers). Later dressings were determined using Hydros N Tester to measure leaf chlorophyll levels. At GS32 (second node) this suggested rates of 20, 45, 65 and 90kg/ha (16, 36, 52 and 76 units/ acre), increasing with sowing rate.
"I think the 20kg was too low for the low drilling rate. I should have had a trial at a higher level," he says. By GS39 (flag leaf), the N Tester indicated dressings of 74, 56, 68 and 90kg/ha (59, 45, 54 and 72 units/acre) were appropriate. "The combine will show if the 74kg has boosted yield enough at 100seeds/sq m."
Fungicide treatments are comparing three Amistar (azoxystrobin) programmes with one involving Landmark (kresoxim-methyl + epoxiconazole) and another based on Opus (epoxiconazole)/Folicur (tebuconazole).
"This year is unique," says Mr Pask, who highlights the absence of any greening effect from the strobilurin fungicides. "Except for tiller count there are no differences between the plots. My gut feeling is that 160seeds/sq m drilling rate will be best.
Fields too dirty?
Worried that your fields are getting dirtier? If so Grass Weed Action 2000 is for you. This joint initiative by Cyanamid, Du Pont and Monsanto and leading agrochemical specialists, intends to relay through farmers weekly the best possible advice on controlling grass weeds.
The nationwide campaign, starting today, stems from the firms determination to encourage integrated controls as widely as possible. It will consist of a series of topical articles and a special supplement setting out the latest advice, technical information and practical experience from independent specialists, agronomists and growers.
"Research and practical experience show there are huge benefits to be gained from well planned winter cereal herbicide sequences effectively integrated with appropriate cultural control measures," says GWA 2000 co-ordinator Chris Gamble of Monsanto. "Our aim is to help farmers weekly readers really get on top of their grass weed problems this season."
Cleavers killer is a UAPtrials success
NEW cleavers killer florasulam (Arable, June 11) seems set to find a place in growers and agronomists broad-leaved weed control plans in cereals next spring.
"This is our third years work with the product and it has been extremely consistent at early timings," says UAPs senior trials officer Derek Lewis. "But at later timings, as with Eagle, you can get more re-growth."
Applications of florasulam on Feb 12 in Kent gave nearly 100% control at both full and two-third rate applications. "The cleavers were at 10cm. It was quite a stiff test for the product," says Mr Lewis. But reducing rates where such large cleavers are the target is not recommended as substantial re-growth has been recorded in previous years, he warns.
Starane (fluroxypyr) plus HBN also worked well in the trial, but 14C (57F) temperatures at the time were exceptional, he says. Current early cleaver control standard, Eagle (amidosulfuron) managed only 91% control at full-rate.
An April application saw control from florasulam fall to 80%, and Eagle to 78%.
In addition to cleavers, the new herbicide, which is expected to be called Boxer, controls volunteer oilseed rape, chickweed, mayweed and groundsel. That wider spectrum, plus the fact it is not a sulfonylurea, appeals to JSR Farms technical director Phillip Huxtable.
As a seed and malting barley grower, his policy is to go in as early as possible to take out cleavers.
"Eagle is a very good fit with early chlormequat timings and still leaves the opportunity to go back if we have to, though that is seldom necessary. But with Eagle the control gaps come after cleavers and volunteer oilseed rape," he adds.
Feed barley gets nod
FORGET malting and go for feed, is the message to winter barley growers north of the border from SAC cereals specialist, David Cranstoun.
Modern varieties have a much higher yield potential, and stronger straw means more nitrogen can be used to take advantage of that. Yields of 10t/ha (4t/acre) should be achievable, he says.
"In the past the yield to nitrogen response curve for barley has gone up quickly, but tended to come down quickly too, due to lodging. With these stiffer varieties we can extend that curve upwards."
Already recommended variety Regina, and candidate variety Artist are the best bet to push for yield in the two-rows, says Dr Cranstoun. Rated at 105 and 107 for yield, respectively, both score 9 for standing power, and Artist offers good specific weights and net blotch resistance, too. While Regina is approved by the Institute of Brewing for malting, it is unlikely to be widely used by distillers, he notes.
In the six-rows, Angela and Siberia are a leap ahead of Manitou, he says.
For maximum yields, drilling should be in September at 300seeds sq m rather than the traditional 500/sq m, and growers should consider using strobilurins, Dr Cranstoun advises. *