9 August 2002

Weed beet is tightening grip

WEED beet infestations continue to spread, with some fields so badly smothered they have been taken out of production.

"Despite a lot of time and money spent on controlling the aggressive weed, the number of fields infested continues to escalate," says Stephen Brown of British Sugar. "It has tightened its grip on the UK crop. Ten years ago it could be found in 15% of beet fields, now it is in 70%."

He believes it is set to worsen as over 98% control is needed to make any impression on infestations. "That is seldom achieved.

"I know of a crop that was so badly infested it was not worth harvesting so it was sprayed off. The devastating build-up occurred over 15 to 20 years despite a lot of money being spent on hoeing and weed wiping," Mr Brown says.

Weed beet shade the crop and compete for nutrients and moisture, with just a single unwanted plant per square metre knocking yield by 10%. A more typical infestation of 8/sq m can halve yield.

"Allowing just a single weed to remain can rapidly lead to a massive infestation. Each one can produce 1500 seeds that can remain viable in soil for 20 or more years. So while control in the early stages of a build-up is relatively cheap, it needs to be effective, as costs rocket as populations take-off." &#42