TAKING A CLOSER look at your nitrogen regime should help achieve malting specification, but pay attention to trace elements and fungicides too, urge Dalgety advisers.
In Scotland, the two distinct markets for malting barley need different fertiliser approaches, says business manager Martin Orr. “In the north, varieties like Optic, Decanter and Chalice are grown for the distilling industry, with its demand for low N grain. “In the south, Cocktail and Optic are grown for brewing, with its slightly higher grain N requirement.”
Starting with the right sowing rate is essential, he says. “Drilling towards the end of March needs a seed rate of 350-375 seeds/m sq. If drilling gets delayed, the rate should be increased.”
Between 50 and 60% of the total nitrogen should be applied in the seed-bed, providing drilling takes place before April. “For distilling, you”ll need around 90 units/acre in total. So put 45-50 units in the seed-bed, with the rest going on as soon as you can see the tramlines.”
Where drilling is delayed until April, all the N should go into the seed-bed.
Spring barley destined for brewing needs 110 units/acre, or 140kg/ha, he suggests. “Don’t apply more than this, or there’s a danger it will go into the heads.”
Sulphur is essential for spring cereals, he says. “The nitrogen to sulphur ratio must be right. Applying 15-20kg/ha of sulphur in the top dressing will ensure that demand is met. Potash should go on then, too.”
Green leaf retention is the aim with fungicides, he adds. “Scottish growers have had problems with abiotic spotting and ramularia in the past couple of seasons.”
For this reason, he recommends a triazole/strobilurin/chlorothalonil mix at the flag-leaf timing. “The strobilurin element helps with ramularia, and the chlorothalonil seems to act like a sunscreen and prevents spotting.”
At T1, rhynchosporium and mildew are threats. “Of the two, rhynchosporium is the main concern. You need to use the strongest chemistry on this disease early to get on top of it.”
New Bayer fungicides, which should be available for spring 2005, will help, Mr Orr believes. “Prothioconazole is very good against rhyncho, so it should be easier to control than before.”
Both manganese and copper can be short in parts of Scotland, but such trace element deficiencies are easy and inexpensive to correct. “The light land tends to be short of manganese. It can be applied as a foliar treatment, or added as a seed treatment.”
Copper problems tend to occur in Aberdeenshire and around Inverness.
Where Pearl is grown in England for malting, growers should aim for 280-300 plants/m sq in the spring, advises the firm’s technical manager Colin Lloyd.
On lower yielding land, the total nitrogen input should not exceed 130kg/ha (104 units/acre). “And that should have all been applied by the beginning of April. GS30 is a good reminder.”
Heavier land can receive up to 140kg/ha in two applications. “The threat with nitrogen is that if there’s a dry spell, it increases the risk of higher grain nitrogen. So it’s best to go early.”
Potash and sulphur are also needed. “Put potash on early in the spring and add 45-50kg/ha of sulphur with the first nitrogen dressing.”
Strobilurin fungicides still provide good disease control, he says. “The biggest response comes from the T1 spray in winter barley, so growers should invest at this stage.”
He suggests using Amistar (azoxystrobin) and Unix (cyprodinil), but recommends adding a triazole if rust is present. “The main disease threats at T1 are rhyncho and net blotch. Occasionally rust will come in early.” Abiotic spotting is not an issue in East Anglia and the south, he says. “The T2 spray has a different role in England. Much depends on disease levels, but a strobilurin/triazole mix, such as Amistar + cyproconazole, is often warranted.”
Growth regulators help to lower screenings and even up tillers, he adds. “Use chlormequat at the end of tillering and a low dose of a Terpal-type product at flag leaf.” Magnesium input must be considered on light soils, he warns.
“If the plant runs short of magnesium, it will strip it out of the flag leaf. As we want the leaf to stay green, applying foliar magnesium to the flag leaf will prevent this occurring.”