Need for increased persistence this autumn

UK - September 20, 2009



With high levels of grass-weed seeds in the seed bank plus the recent advice that black-grass dormancy will be high, the need for longer lasting, persistent weed control will be greater this autumn, according to Dow AgroSciences.

"Grass-weed control in many cereals crops last year wasn't great and many "dirty" crops at harvest would have added to the weed seed bank.  On top of this ADAS have advised that black-grass seed dormancy will be high this year.  This means that black-grass germination will be extended, even with adequate moisture.  Finally in the Eastern counties oilseed rape has been drilled into dry seedbeds and so germination of both crop and weeds has been delayed.  These factors combined will require high levels of persistent weed control with robust herbicides" says Rene Pollak, Regional Business Manager for Dow AgroSciences.

"Most farmers, particularly those that were caught out by dreadful conditions last autumn, have concentrated on getting their crops sown on time.  Once drilled up, the priority has been to apply a residual herbicide to cover the first flush of broad-leaved and grass weeds.  However in many cases the pre emergence herbicides slot has been missed and in others dry conditions are likely to lead to less than optimal activity.  Under such circumstances, it is a good thing that farmers can rely on Kerb Flo with its highly potent residual grass and broad-leaved weed activity to give long lasting residual control in both winter oilseed rape and beans."

Rene says when conditions are ideal, Kerb will give highly persistent control of black-grass in excess of three months. "If everything is perfect and it is applied in cool, moist conditions, propyzamide will still be working in January, February and even March.  In ADAS trials it gave 98% control of black-grass, a level that few herbicides in rape or cereals can achieve these days. In further trials applied in October, it gave 100% control of annual meadow-grass."

"In order to get the best from propyzamide, soil temperatures need to be low, between 5ºC and 10ºC.  Ideally the soil temperatures should be below 8ºC and the plants growing slowly.  At these lower temperatures, breakdown of the chemical is slowed down and so longer persistence is achieved throughout the weed germination period.  Good levels of soil moisture are also needed to help the herbicide distribute evenly in the top few cms of the soil, as Kerb is absorbed by the roots," says Rene.

He explains that Dow AgroSciences provides advisors with regular reports at a local level on soil temperature and moisture deficits to help them achieve optimum conditions for application.  "This support is invaluable to get the best out of Kerb.  We work hard to keep tank mix compatibilities up to date and advise on and work with many other organisations to extend the use of Kerb Flo into other crops.  Online topical support can be found on the Dow AgroSciences web site, www.dowagro.com/uk."