Creeping thistle too competitive for beet crop

UK - May 20, 2004

High levels of creeping thistle are appearing in sugar beet crops across the country warns Dow AgroSciences.

“Growers and distributors alike are starting to report significant levels of creeping thistle which is incredibly competitive in sugar beet,” says Rene Pollak, agronomist with Dow AgroSciences.

“Failure to control the aggressive, tall-growing perennial weed can reduce yields by up to two-thirds by shading and competition for moisture. Even after harvest the weed can cause troubles such as heating in the clamp.”

Trials data shows that just one thistle a square metre can cause losses of up to one t/ha of clean sugar beet yield. Thistle patches are invariably denser than this.

Mike May from Broom’s Barn Research Station advises Dow Shield^† as part of the post-emergence weed control programme to control creeping thistle effectively. “The first treatment should be at 0.5l/ha while the thistle crops are at a rosette stage. For complete control this should be followed up with a further application of 1.0l/ha up to four weeks later, but before the end of June.”

The first spray stops thistle plants developing with a loss of apical dominance. The weed then compensates by stimulating the emergence of shoots from other parts of the thistle rhizome.

“The second, higher dose spray, then literally gets down into the root of the problem. It’s translocated through the thistle plant — top growth and roots — to give complete weed control,” explains Mr May.

“Growers regard Shield as an expensive product, but the economics of creeping thistle control means for every £1.00 spent protecting yield loss from thistles, there is a potential £10 return in clean beet yield. And it also assures a clean entry for following crops in the rotation,” adds Mr Pollak.

^† Trademark of The Dow Chemical Company