Abstract
Three experiments were conducted in the greenhouse to study the biology and the effectiveness of several herbicides on Alexander grass (Brachiaria plantaginea). The first experiment, designed to establish the length of stolons to be used in further experiments, showed that two-node runners (regardless of the size of the fragment) was the best planting material. In the second experiment the following herbicides were applied to plastic trays (20 cm x 20 cm x 23 cm) filled with soil and planted to Brachiaria runners (2 per tray) as a pre-emergence treatment: hexazinone [(3-cyclo-hexyl-6-(dimethylamino)-1- methyl-1,3,5-triazine-2,4(1H,3H)-dione)] at the rate of .5 kg/ha and 1 kg/ha; bromacil (5-bromo-3-sec-butyl-6-methyl-uracil) at the rates of 2 and 4 kg/ha; diuron [(3-(3,4-dichlorophenyl)-1,1-dimethylurea)] at the rate of 4 kg/ha; metribuzin [(4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)-one)] at the rates of 2, 4 and 8 kg/ha; Krovar I (1:1 bromacil + diuron) at 4 kg/ha and Krovar II (.53 bromacil + .27 diuron) at 4 kg/ha; a combination of ametryn [(2- ethylamino-4-(isopropylamino)-6-methylthio-s-triazine] + atrazine [(2-chloro- 4-(ethylamono)-s-triazine] at 2 + 2 kg/ha; a combination of ametryn + metribuzin at 2 + 2 kg/ha. All individual herbicides and their combinations were highly effective in controlling the sprouting of the runners for a 2-month observation. In contrast, in the non-treated trays, runners sprouted 100%. In the third experiment, runners were pre-rooted in nontreated soil and transplanted to trays filled with soil treated 2 months before with the above mentioned herbicides were totally injured, and eventually killed after 30 days. Untreated runners developed under normal conditions up to 30 days.