Archive Article: 2001/10/20 - Farmers Weekly

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Archive Article: 2001/10/20

20 October 2001

Xi19 on trial

NEW wheat Xi19 is not one for early sowing, according to trials done by Advanta Seeds.

By early, the company means up to mid-September. If sown then, rapid development – perhaps just 187 days – up to first node (GS31) might create a too "leggy" plant, and put the embryonic ear at risk from frost in late February to early March. For comparison, early sown Consort or Savannah take 203 days to reach GS31.

When drilled in October, Xi19 shows slower development. Last seasons results show the variety to mirror Consort and Savannah, in trials sown on 26 October. In a look-see at late February drilling dates, the wheat reverts to fast development, reaching GS30/31 after just 87 days, far ahead of Consort at 95 days.

"This confirms our advice that Xi19 should not be drilled in the first half of September," says Advantas Paul Hickman. "The earliest optimum drilling date for Xi19 in the southern half of the UK should be early October, but that date could be brought forward to the latter part of September as you move north of the Wash."

Yield results from the 2001 harvest, in NIAB trials commissioned by Advanta, show the variety gave 13.7t/ha when drilled on 26 September, compared with 13.4t/ha drilled on 14 Oct (see graph).

To achieve top milling protein spec with Xi19, fertiliser management may need attention. Trials done by the Arable Research Centre point to best results, and a 12% DM protein, from a late foliar N treatment of 40kg/ha, with sulphur, over and above what would be standard N application for feed wheat. The addition of sulphur lifted grain protein by 0.5%.

"If more nitrogen is applied, Xi19 does take in more. Liquid N plus sulphur shows the best overall protein yield results," says Mr Hickman.

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Archive Article: 2001/10/20

20 October 2001

"We are seeing more and more leaves chewed off at ground level in early drilled wheats after grass leys and grassy set-aside. I am having to recommend seed treatment with Secur to prevent crop losses."

Also localised, gout fly have had a stab at reducing populations by eating out the central shoot. But if no more than a quarter of plants have gouted shoots, there are probably enough left, stresses Mr Oakley. The threat is now dwindling.

"The gout flys small, white cigar shaped eggs will all have been laid by now on the upper leaves of wheat plants. You may see some of the tiny, yellow larvae if you open up the shoot, but the damage is already done. So unless the pest has taken out too many plants, theres nothing you need to do."

Slugs are a different matter. Slug activity is high where seedbeds were cloddy at drilling, particularly where rain has recently fallen.

The only other pest to cause concern is the wheat bulb fly, a particularly high risk after potatoes, beet and set-aside fallow. While problems wont show up until the New Year, its time to assess the risk before its too late. Any fields at risk should be sampled, ideally, before cultivations disturb the soil, he warns .

Egg counts in soil will indicate the likelihood of later infestation. Early counts suggest average levels this season, though the risk is higher than in previous years in potato growing regions of Scotland, says Dr Evans.

If there is a history of the pest on the farm, or egg numbers exceed the threshold, he and Mr Parish recommend growers use the seed treatment tefluthrin (Evict) on late sown crops rather than wait until damage appears and use an egg hatch or a deadheart spray. Evict and follow-up sprays work best if seed is drilled to less than 40mm (1.5in) and the seedbed is consolidated, according to the results of a small, continuing trial carried out by ADAS and Bayer.

Turning to diseases, winter wheat drilled exceptionally early, as some were in the south, may be at greater risk from mildew as the autumn progresses. Oilseed rape is in more immediate danger, from phoma in the south and light leaf spot in the north and Scotland.

The first phoma lesions appeared a few weeks ago in the far south, says Mr Power. The inoculum came from neighbouring rape stubble, which is becoming a lower risk as cereal drilling progresses. Infection can take only 10 days from start to finish, he warns.

If lesions can be found on 10-20% of plants, he advises starting a two-spray programme four to six weeks apart of either flusilazole and carbendazim (Punch C) or difenoconazole (Plover). Half rates of each should hold the disease, he adds.

In Scotland, where light leaf spot is high risk, Dr Evans is recommending Punch C or tebuconazole (Folicur) at this stage, the optimum timing for control. There is a large reservoir of inoculum and the weather is favouring disease development.

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Archive Article: 2001/10/20

20 October 2001

Headache for oilseed rape

TARGET site resistant blackgrass is a bigger headache in oilseed rape than wheat, according to ADASs David Parish. Some of his Bedfordshire farming clients are switching to winter beans in order to take advantage of the opportunity to plough and kill the first weed flush with glyphosate.

He is very concerned about the increasing incidence of target site resistant blackgrass and estimates that probably 75% of his clients farms have it at some level, although not in all fields. Samples analysed at ADAS Boxwoth show that in 1999, 30% of samples analysed were target site resistant. In 2000 this leapt to 50% and is now 53% this season, although fewer blackgrass samples have been analysed.

Target site resistant blackgrass limits product choice in oilseed rape "Once you have taken out Aramo, Laser, Falcon, Fusilade and Pilot (fops and dims) from your weed control armoury you are only left with trifluralin, Butisan, Kerb or Carbetamex."

They all have their limitations: "Trifluralin needs incorporating into the soil. Butisan cannot be used pre-emergence where oilseed rape crops are broadcast or Autocast. Kerb and Carbetamex cannot be applied before 1 October; by then blackgrass plants may already be tillering. In good conditions Kerb can give good control, but in a dry autumn or on deep-rooted blackgrass it can be less effective. Carbetamex is more soluble than Kerb so can be less effective in wet winters."

So what should growers do? Key areas to address include:

1 Cultural controls

The importance of controlling weeds pre-drilling cannot be overstated. But it is hard work to do; given recent autumns it is more tempting to drill than wait 24 hours to spray off an early weed flush

2 Gear product strategy to residuals

Avadex, Crystal, Stomp and Lexus post emergence as well as chlortoluron and ipu give residual activity. Unfortunately enhanced metabolic resistant blackgrass are tolerant, to varying degrees, to this group of herbicides

3 Quality of seedbed

The residual route rests entirely on obtaining a good seedbed; without it, the effectiveness of these products falls off rapidly. Also ensure an adequate drilling depth so that the choice of herbicide is not limited

4 Choice of break crop

Achieving control of target site resistant blackgrass in oilseed rape is become increasingly difficult. Winter beans offer greater cultural and product flexibility

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