VIDEO: Crop Watch – rape suffering in drought

Oilseed rape is suffering the most in the spring drought with reports of flower abortion particularly affecting light land crops, say our Crop Watch agronomists.

Parched crops are sitting at the yellow bud stage with flowers aborting before they open, says Buckinghamshire’s ProCam agronomist Nick Brown.

“Crops on thin, brashy soils have been hit hardest, but damage is variable,” he adds. “Some crops grown on brash look really well while others look awful – a dirty yellow colour with few, if any open flowers.”

DK Cabernet is one of the worst affected varieties and most hybrids generally look much better, he says.

In Shropshire, oilseed rape crops range from 25-80% flowering, according to AICC agronomist Bryce Rham.

Cubic is the most forward with the main raceme having 80% developed pods and petals dropping with a percentage sticking to the leaves,” he says.

Mr Rham has also found seed weevils in some crops and seen two crops with significant club root symptoms.

Despite the continued dry weather, our agronomists are sticking to their spring spraying programmes.

Sclerotinia sprays are being applied even though conditions are dry, says Suffolk agronomist Brian Ross, of Frontier Agriculture.

“Heavy dews are enough to allow apothecia to release spores, especially with recent high temperatures. But with overnight temperatures remaining above 7C, the threat of developing sclerotinia remains.”

In Yorkshire, AICC agronomist Patrick Stephenson says oilseed rape crops have either received a sclerotinia spray or are due one imminently.

“My favoured mix has been based around prothioconazole with a partner product,” he says.

“Most models for sclerotinia risk were triggered earlier this month, but with no rain and no flowers, I have advocated delaying applications until petal fall.”

Meanwhile, an explosion of yellow rust in winter wheat crops on 10 April triggered the spraying programme in some crops which had not received a T0 fungicide spray, says Mr Stephenson.

But for varieties not prone to the disease, discussions have been focusing on when to spray and whether it is possible to reduce rates of active ingredients given the dry conditions.

“In short, you should still spray and you can cut rates, but not by huge amounts,” he recommends.

Mr Ross says Oakley has been hit hardest by yellow rust, but Viscount, Duxford and Solstice have also been affected, albeit less seriously.

“We have the armoury to deal with it, but it is yet another cost despite high wheat prices,” he adds.

For potato growers, weeds are emerging and the dry conditions are making herbicide choices challenging as the residual element relies on moisture, says Yorkshire-based SAC agronomist John Sarup.

“I will probably use linuron at the maximum allowed 600g of active plus a low rate of metribuzin, where variety allows, plus diquat or carfentrazone, depending on emerged weed spectrum with a follow up post-emergence application of rimsulfuron,” he adds.


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