CREEPING THISTLES are an increasing problem in sugar beet fields and the problem could get worse, experts have predicted.

Over the past decade the weed has increased by wind-dispersed seed from naturally regenerating set-aside and poor control of established populations, said Brooms Barn’s Keith Jaggard.

“Deep-rooted rhizomes make it very difficult to kill completely and its thistledown seeds can be blown over many miles.”

Just one creeping thistle stem per m² can cause a yield loss of 1t/ha in sugar beet, he noted.

In many cases, glyphosate and in-crop cereal herbicides fail to give adequate control, added Dow AgroSciences’ Colin Bowers. “With the area of fallow margins set to increase, the weed population is likely to rise further.”

Spot spraying affected areas is one option, although this often means weeds are missed and an overall spray may be more appropriate, he said.

In such cases, he recommends using Dow Shield (clopyralid), with the first application when thistles are at rosette stage and a follow-up three to four weeks later.