Crop Watch: Top up nutrients with sprays

Early fungicide timings are the ideal opportunity to correct nutrient deficiencies in oilseed rape and wheat crops, according to our Crop Watch agronomists.


In Cambridgeshire, oilseed rape tissue sampling indicated low levels of phosphorus, potassium, magnesium and molybdenum, said UAP agronomist Will Foss. “Foliar applications of these nutrients will be included with fungicide treatments to support the crop in this period of high demand.”

Plant growth regulator fungicides would be applied once oilseed rape had reached stem extension, he noted. “Any backward crops will be monitored for light leaf spot, but will probably not get a fungicide until late green bud/early yellow bud.”

Spring barley had generally been drilled into good seed beds, although some of the later-ploughed, heavier soils still needed to dry out. “Pre-emergence herbicides are being applied to spring barley where grassweeds are an issue.”

In Gloucestershire, wheat was approaching the T0 fungicide timing, said Countrywide Farmers agronomist Neil Donkin. “T0 is also a good time to correct trace element deficiencies, with manganese being the most obvious requirement at present.”

T0s were generally applied around 20 March and there was mildew in most crops as well as septoria, he said. “Wheat will very often grow away from mildew so whether a specific mildewicide should be added at the T0 stage is a matter of opinion.”

Varietal susceptibility and severity of the mildew would be the main considerations, he noted.

Many growers in the area were preparing ground for maize drilling, said Mr Donkin. “Before applying farmyard manure, it is worth assessing weed growth and applying glyphosate if necessary to ensure a clean start once the crop is drilled.”

AICC agronomist Hamish Coutts from Perthshire said some compound fertiliser had been applied to crops that missed out in the autumn, as well as straight nitrogen on oilseed rape and winter barley. “However, all this activity has ground to halt over the weekend with heavy rain and up to 5cm of snow in many parts of the country,” he said.

Evidence of old mildew and the occasional trace of net blotch or rhynchosporium had been spotted on winter barley. “When weather permits, a low-cost fungicide should be sufficient to clean the crop up until GS31, which is the optimum timing for disease control.”

Winter wheat crops looked reasonably clean, but Oakley, Robigus and Viscount would be monitored for yellow rust and all crops needed to be checked for mildew, he added.

In Kent, problem blackgrass was being treated with Atlantis (mesosulfuron + iodosulfuron), said Masstock agronomist Colin Sharp. “We’re putting on full rate with Biopower plus extra adjuvant for penetration and water conditioning. This combination has given a valuable 2%-3% extra control in some of our trials.”

High levels of mildew had been seen in wheat and barley and all varieties were being affected. “It shouldn’t be a problem with our good strong, healthy crops, but we’re keeping a careful eye on more backward ones that could suffer badly.”

Most wheat crops would be treated with a triazole plus chlorothalonil at T0, he said. “We’ll be adding a mildewicide wherever we have any doubt, to nip problems in the bud.”

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