Bush.control studies in the drier areas of Kenya. 6. Effects of fenuron (3.phenyI-.l,l. dimethylurea).
Abstract
In field tests with fenuron pellets, Commiphora spp. and broad.leaved shrubs (Maytenus putter. lickioides, Premna oligotricha and Tarchonanthus camphoratus) were mostly tolerant of the recommended dose of about 7 g a.i. applied at the base of established plants, but most Acacia spp. and Dichrostachys cinérea were sensitive to treatment, especially Acacia mellifera ssp. mellifera and A. reficiens ssp. misera under arid conditions, where mortality was 100%. Between 75 and 80% control of A. drepanolobium was obtained with fenoprop at 3 g a.i./tree applied basally at the onset of a rainy season, followed by burning 6 months later, but when application was deferred 7 weeks or burning was omitted or deferred 2 years the kill was nearer 50%. Mortalities of 50% were obtained also with 0.75 and 1.5 g a.i., provided that burning followed soon after treatment, suggesting that a double application of very low dosages might prove the most economical way of using fenuron. F.s.-J.L.M.