VOLUNTEER POTATOES are an increasing problem in many crops and can significantly reduce sugar beet yields in particular, Dow AgroSciences has warned.

A population of five potatoes/m²  can reduce beet yields by up to 22t/ha, so removing them is essential for that beet crop and following potato crops, said the firm’s Colin Bowers.

Volunteers also act as a reservoir for various diseases, including spraing, potato cyst nematode, scurf, black dot and aphid-transmitted viruses, said Dow’s John Sellars.

“Shorter rotations, use of rented land and growing certain varieties, such as Maris Piper, Saturna and Cara, that tend to produce chats, are all conducive to the increase in the volunteer problem.”

Growers should adopt an integrated approach to their control, using a variety of chemical and cultural means, he advised.

In a survey of control options by Dow AgroSciences, 70% of growers used glyphosate pre-harvest, 56% used Starane (fluroxypyr) in cereals and 46% avoided ploughing after the potato crop had been harvested.

The company recommends growers use a split application of 0.5l/ha Dow Shield (clopyralid) with Betanal Flo (phenmedipham) and Nortron Flo (ethofumesate), with the first application when potatoes are 5-10cm tall and the second at 10-20cm, 7-14 days after.