20 September 2001
Watch weather with pre-em sprays

By FARMERS WEEKLY staff

GROWERS have been advised to consider changing their pre-emergence treatment for blackgrass on early drillings if forecast warmer weather persists.

Bob Mills of Banks Cargill has warned that higher temperatures serve to shorten the residual life of Avadex (tri-allate) – mainly an issue on early-drilled crops.

“For maximum sensitisation you need four to six weeks before applying a post-emergence treatment,” he advises.

Mr Mills believes the residual activity and different mode of action of Crystal (flufenacet + pendimethalin) make it more robust in milder conditions.

Target weed should also decide pre-em choice: “Crystal definitely has the edge where ryegrass and meadow grass are an issue.”

Where blackgrass is the sole problem the two choices perform about the same, he says, while Avadex probably has the edge if wild oats are also present.

Full-rate Crystal costs about 32/ha and can be applied with a farm sprayer. Avadex costs less at 22/ha, but application costs may add another 7.50-8/ha.

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