The fungicide tridemorph as a selective herbicide for the control of Holcus lanatus in ryegrass and of Bonus sterilis in barly

Summary The potential of the fungicide tridemorph selectively to control established plants of Holcus lanatus L. in ryegrass ( Lolium perenne L) and Bromus sterilis L. in barley ( Hordeum vulgare L.) was examined in glasshouse trails. A dose of 4.2 kg ha −1 tridemorph gave selectively between H. lanatus and ryegrass similar to, but more costly than, that which would be provided by 1.2 kg ha −1 asulam. B sterilis was more sensitive to tridemorph than was barley. Two additives, glycerol and the oil‐surfactant mixture ‘PF’ enhanced this selectivity when tridemorph was applied at 2.1 kg ha −1 .