23 November 2001

Rape needs additional sulphur now

ADD elemental sulphur to second phoma sprays for oilseed rape, suggests Suffolk-based independent agronomist Dan Robinson.

"Several crops on marginal soils last year showed severe deficiency symptoms. By the time growers could get the sulphur fertiliser on it was too late," he says.

A foliar spray such as Thiovit now will help nip developing deficiency problems in the bud, save a pass through the crop, and buy some time before the spring sulphur-based fertiliser is needed.

Where phoma sprays have been completed and severe sulphur deficiency symptoms are developing a sulphur-based fertiliser such as Double Top should be considered, even though some of the nitrogen may be lost through leaching, he says.

On heavier soils with less severe deficiency an elemental sulphur fertiliser such as Tiger 90, which will breakdown over winter is an alternative, he adds.

"Hybrid rape varieties appear to be most susceptible to sulphur deficiency. Last year the problem showed up by increasing branching and flower production, to the extent that the crop wouldnt stop flowering and yield was consequently poor."

Meanwhile, Dalgetys Barry Barker warns that forward early flowering varieties like Disco, Winner, Borneo and Elan could run into pod-set problems in the spring.

"A few years ago the variety Contact – with an 8 for earliness of flowering – suffered from late frosts and in some cases collapsed under snow. Crops are probably further forward now than they were then.

"Unfortunately, there is little growers can do about how early the crop flowers. But they can regularly monitor disease levels and take agronomists advice on nitrogen, sulphur, micronutrient and fungicide applications." &#42