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Correct Flail and Spray Pivotal to Burndown Success – Agronomist and Arable Farmer – Rich Daubney

With flail and spray now the preferred option in potato desiccation, Rich Daubney explains key points that can help growers achieve a cost effective and timely burn down ...

Rich Daubney manages potato crops on mainly grade one silts in south Lincolnshire, north Cambridgeshire and Norfolk. His customers produce packing and chipping quality potatoes, including varieties such as Maris Piper, Melody, Agria, Markies and Sagitta. Yields average 45-60t/ha off the field.

Desiccation has been a key focus for his growers following the demise of diquat and his replacement product of choice is the stem desiccant Spotlight Plus.

“Desiccation quality relies on sunlight so as light intensity decreases over the season, growers need to be more patient with the speed of knockdown,” says Mr Daubney.

“Spotlight usually takes around seven days after application before activity becomes visual.”


He says that Spotlight Plus works most efficiently where it is being used in combination with a mechanical flail that has previously removed the leaf vegetation and other detritus, leaving the stem exposed to the full impact of the chemical. A flail and spray programme can be just as effective at killing off the crop canopy as diquat was before it was banned.

“With flail and spray now the preferred desiccation option, there are some very important and key factors to consider prior to adopting this technique,” he says. “A flailed crop should be left for 24 hours before applying Spotlight.

This gives time for debris to settle and stems to stand more upright after the flail press wheel. Attention should be taken to maintain just enough weight on the ridge to seal cracks, without causing too much disturbance and pressure. This increases the target area of the stem for the desiccant to hit.

“Also, ensure that forward speed is not too high, flail blades are sharp and have been set up to a correct stem cut length of about 6-7 inches, flailed debris is directed into the bottom of the rows away from ridge tops.”

Where flail and spray is being adopted, Mr Daubney urges growers to give extra consideration to their crop nutrition strategy, particularly avoiding excess nitrogen inputs and making an appropriate varietal choice.

“Excess nitrogen, in particular, can make skin set markedly more challenging by delaying senescence. This is not easy to predict, especially with the ever more sporadic weather events we now seem to experience,” Mr Daubney adds.

Skin set is critical, so the aim must be to push the crop on to bulk as early as possible, using foliar feed where necessary.

He advocates flailing a potato crop 24 hours before applying Spotlight Plus at 1l/ha followed potentially by a second application of Spotlight at 0.61/ha 7-10 days later, especially on indeterminate varieties.

“If a crop looks full and lush before the first desiccant application, do not wait too long to see what performance the 1l/ha rate gives,” advises Mr Daubney. “Plan to go in again before any regrowth is visible. But, one to two applications of Spotlight is often enough and growers rarely need to use other desiccants such as Gozai, which has a longer harvest interval.”

Correct nozzle selection can also have a significant impact on the effectiveness of the desiccation programme. Mr Daubney prefers a nozzle that produces optimum coverage rather than always relying on high water volumes to achieve the necessary crop coverage.

“We are aiming for good coverage with higher chemical concentrations within each droplet, and this can often give better results,” he adds.

“Nozzle technology has come on massively recently, so we are already achieving better coverage than in the past. As a result we rarely need to go in with Gozai after Spotlight – possibly on late crops near the end of September.”

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