Growers considering chlorotoluron (CTU) as an IPU alternative in black-grass control programmes need to be aware of sequence restrictions with Atlantis WG, a leading herbicide expert has warned.

Increased emphasis on autumn Atlantis treatment has reduced the need for a “holding spray” but, for growers delaying sulphonylurea treatment until later in the season, CTU will be seen - and is already being advocated - as a potential IPU alternative. Experts at Bayer CropScience warn, however, that this move could backfire later in the season if not carefully planned.

Gordon Anderson-Taylor of Bayer said: “Where CTU is followed by Atlantis, growers must leave a four to six week gap between treatments otherwise they run the risk of antagonism with Atlantis. Failure to plan for this could mean Atlantis treatments are pushed into the spring which, experience has shown, is not the best timing.

“After several years of use, we are now into the sixth season of Atlantis. It is clear that, wherever conditions allow, Atlantis should be applied in the autumn. Spring-applied Atlantis may deliver a clean looking crop but by delaying treatment, competition will reduce crop density, increase resistance risk, and compromise yield potential.

“Autumn applied Atlantis plus bio-power and a residual partner at the 2-3 leaf stage of black-grass has given the most consistent control and optimum yield,” he added.

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