24 August 2001

For best burn-down

WITH many potato crops still growing vigorously, growers should be prepared to make two passes to achieve effective burn-down, says SACs Fraser Milne.

"Think about how dense the canopy is – will you be able to do the job in one hit?"

If spray will not penetrate to the stems then opening up the canopy first with a low dose of desiccant is recommended.

"In a dense crop acid is best but Reglone is cheaper and if agronomy is right it is a good alternative."

Syngenta recommends 0.5 litres/ha then 3.5 litres/ha if haulm is senescing, or where growth is still vigorous 1 litre/ha followed by 3 litres/ha. Cost is about £32/ha, says the firms Gary Stobbart.

Being SMART

To check desiccation with Reglone (diquat) will not cause intra-vascular browning, do the SMART test – Soil Moisture Assessment for Reglone Treatment – before application, says Syngenta. In each field at several points, including known dry spots, dig down to about 5cm below the deepest tuber in the centre of the ridge. Squeeze soil into a ball by hand and if it holds then there is sufficient moisture for safe application.