SUMMARY Glyphosate sprayed at 1.1, 2.2, 4.5 or 6.7 kg/ha on to bracken decreased the total carbohydrate content of the storage rhizome 20 months after spraying, the decrease being greater when spraying was carried out at the beginning rather than at the end of August. Asulam, benazolin and metribuzin, although reducing frond numbers, showed no significant effect on the rhizomes over the same period.