Crop Watch: Phoma present in OSR at threshold levels

Continued poor weather means many workloads are falling further behind for our Crop Watch agronomists this week, with concerns rising over phoma levels and blackgrass control.

Procam agronomist Nick Brown was reminded of Morecambe Bay at low tide when walking his earlier drilled wheat crops this week. “The very worst fields look like Morecambe Bay when the tide has gone out.

“Of the wheat that has been planted some is emerging well, with little slug activity. The bulk of the area planted to date follows oilseed rape and a combination of extreme slug pressure, an inability to roll, seed with seemingly poor vigour and waterlogged soils causing seed to rot means much of the drilled area does not look pretty,” says Mr Brown.

A little further east, Strutt and Parker’s Ryan Hudson is happy to have 80% of his planned area in the ground. In the west, Neil Donkin urges growers not to give up on winter drilling just yet and points out that broadcasting cereals is a viable last resort.

“The very worst fields look like Morecambe Bay when the tide has gone out.”
Nick Brown, Procam agronomist

It’s not just drilling being affected, pre-emergence sprays are also being delayed by the weather. “To avoid herbicide damage where the crop has not been rolled my advice is be careful, check seed depth and, if necessary, wait until rain settles the loose soil covering the seed before application,” advises Mr Brown.

Where clomazone has been included as part of the oilseed rape herbicide package, familiar bleaching symptoms are appearing, says AICC agronomist Hamish Coutts. “These should disappear in due course as the crops grow on.”

Propyzamide will be the active ingredient of choice for those fields not yet treated. “Wait till the soil temperature has dropped and the leaves have waxed up prior to application,” says Mr Cooutts.

Mr Donkin agrees it’s too early, but suggests this may change “rapidly if today’s weather forecast is accurate.”

Phoma is now present at threshold levels, warns Mr Brown, but there is a reluctance to spend money on these for fear of them “not making it through winter”. But if these small crops are not treated as soon as phoma appears, yield potential will be severely limited and the yield loss could be as high as 30-40%, he adds.

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