Herbicides for weed control in the root crops Ullucus tuberosus and Amorphophallus konjac

Ullucus tuberosus and Amorphophallus konjac are new root crops being evaluated for commercial development in New Zealand. Eighteen herbicides were screened in glasshouse experiments for pre- or postemergence use in these crops. Methabenzthiazuron, chlorpropham, diuron and linuron were well tolerated by Ullucus when applied preemergence, while dimethanamid, oryzalin and simazine warrant further study. All the post-emergence treatments damaged Ullucus although linuron might show acceptable tolerance at a lower rate. Acetochlor, chlopropham, dimethanamid, linuron, methabenzthiazuron, oryzalin, oxadiazon, oxyfluorfen and pendimethalin were all well tolerated by Amorphophallus when applied pre-emergence, while asulam, flumetsulam and tribenuron were safely used post-emergence. Bromoxynil was also safe on Amorphophallus if applied before leaves emerged from the developing shoot.