Preliminary Screening of 17 Tropical Grasses for Tolerance to Eight Gramineaceo Herbicides

Successful seed production of tropical grasses depends on effective weed control. In particular, annual grass weeds compete strongly with perennial grass seed crops during establishment, and invasion by other perennial grasses can also occur. Glasshouse screening experiments involving 15 tropical grass cultivars and two perennial grass weeds were carried out to identify herbicide and grass combinations warranting more detailed investigation. Herbicides at standard ·rates for arable crops were applied either pre-emergence (at sowing) or post-emergence (14 days after sowing). Metribuzin and four herbicides developed for wild oats control (diclofop-methyl, flamprop-methyl, tralkoxydim, tri-allate) showed almost no useful selectiviiy. Marked differences, however, were recorded between species in their tolerance to atrazine and two sulfonylurea herbicides, chlorsulfuron and metsulfuron methyl