27 September 1996

Cutting mayweed cost

FARMERS can reduce the cost of mayweed control in oilseed rape by about 30% if sprays of clopyralid (Dow Shield) are applied before the first severe frosts this year, according to manufacturer DowElanco.

"Herbicides find it more difficult to penetrate the waxy outer layer of weed leaves once they have been hardened by frost," explains Donald Westwater of DowElanco. "A higher dose rate is required if control is left until later in the season.

"If applied early – before the weed has developed more than four true leaves – rates can effectively be cut by one third to 0.35 litres/ha without compromising control.