Flails look useful aids to desiccation techniques

17 September 1999

Flails look useful aids to desiccation techniques

There was technical advice

aplenty at last weeks

British Potato 99 event

organised by the British

Potato Council at Newark,

Notts. But growers were

warned to look beyond the

farm gate to be successful.

Andrew Blake and

Andrew Swallow report the

highlights over the following

two pages. See page 72 for

machinery developments

FLAILING is proving promising as an aid to chemical and flame desiccation, according to Simon Bowen of Greenvale AP.

"Sulphuric acid is still the number one desiccant. But it is under increasing pressure so we are working hard to find alternatives and that includes re-visiting flailing."

Desiccants like Harvest (glufosinate-ammonium) and Reglone (diquat) perform well in warm weather, but can be slow to act in cooler conditions. "Reglone takes ages to work if it is cold."

Added tin blight sprays speed the effect of Harvest. But flailing ahead of either product can be helpful, as demonstration plots of Cara showed.

Concerns about spreading disease has been reduced with modern flail units, said Dr Bowen. "And its OK if you do it on a dry and healthy crop. The problem is that you very quickly get re-growth which you must finish off. All the while its there the skins wont set." A sequence of flailing and 4litres/ha of Reglone had worked particularly well.

Another approach was a one-pass system with a front-mounted flail ahead of a two-row Greenburner as offered by Sands Agricultural Services and Greenvale. Speed of operation, already slow, appeared critical, noted Dr Bowen. "You can definitely go too fast. 3mph is a waste of money." But surprisingly 2mph proved more effective than 1mph, probably because of haulm build up at the slower speed.

Skin set scores six days after the treatments showed distinct variation (see table). But Dr Bowen expected the differences to be less by lifting time. "We would generally leave them 21 days for a full skin set."

Whatever the approach, the proper place to check skin set was at the "rose" end of the tubers. Setting was much faster at the "heel" and could be misleading, he warned.

Skin set scores

(%) after six days

Untreated 50.3

Flail 60.2

Flail & Reglone 63.4

Flail & burn 63.6

Reglone 70.1

Harvest & tin 70.1

Harvest 73.5

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