Watch out for late emerging weeds in beet

Recent wet weather could encourage a flush of late emerging weeds in sugar beet and growers need to monitor crops closely and be prepared to spray, the British Beet Research Organisation (BBRO) has advised.

While many weed control programmes are coming to an end, particular attention should be given to tall weeds such as fat-hen, redshank, pale persicaria, volunteer oilseed rape, black nightshade and black bindweed, said Broom’s Barn’s Mike May.

“Where these weeds emerge, it is likely that residual herbicide activity is very low, therefore subsequent sprays should be selected as though they were first in the programme (i.e. some contact and some residual).”

Creeping thistles and volunteer potatoes also need to be controlled, he said.

Controlling volunteer potatoes in sugar beet can help reduce potential problems in later rotations, added The Arable Group’s Martin Lainsbury.

Trials in 2004 showed that the addition of DowShield (clopyralid) to Betanal Flow (phenmedipham) and Nortron Flo (ethofumesate) gave the highest reduction of daughter tubers and the best foliage knock back, as well as recording the highest yield gain, he said.

“A total of 1.0 l/ha of DowShield provides a good kill of volunteer potatoes as well as reducing yield and viability of daughter tubers.

“As potato emergence can be protracted, we recommend at least two applications 10-14 days apart for best results. First applications should be made when the most forward tubers have 10cm of leaf growth.”