26 October 2001

Precise spray for blackgrass

GROWERS who suspect they have herbicide resistant blackgrass need to get populations tested to identify the exact type of resistance involved.

Without such information farmers and advisers may do more harm than good, warns UAP herbicide specialist Brin Hughes.

"There appears to be an increasing trend for growers to carry on regardless and use Laser or Aramo type chemistry to control blackgrass in their break crops." With no up-to-date knowledge on the resistance involved growers can encourage target site resistance, Mr Hughes maintains.

His advice, even for growers who dont feel they have a serious problem, is to check for the type of resistance using Rapid Test petri-dish analysis developed by IACR Rothamsted. Control strategies can then be adjusted accordingly.

Results from UAP customer tests suggest target site resistance can then be managed. This year 8% of populations tested by UAP had target site resistance, compared with 24% in 1999. &#42

That suggests UAPs policy of integrated use of glyphosate, cultivation and pre-em chemistry, plus an appropriate post-em spray, can be effective at minimising resistance build-up, concludes Mr Hughes.