Field evaluation of six pre-emergent herbicides for weed control in the cultivation of five leafy vegetables in Singapore.
Six pre-emergent herbicides, Afalon [linuron], Afalon-S [linuron + monolinuron], Devrinol [napropamide], Dual [metolachlor], Lasso [alachlor] and Tok E-25 [nitrofen] at 1.0 or 1.5 kg/ha were evaluated for the control of 15 common weeds in crops of Brassica chinensis, B. alboglabra, Amaranthus gangeticus[tricolor], Ipomoea aquatica and lettuce. All the herbicides tested were more effective for the control of weed seedlings than for vegetatively propagated weeds such as Cyperus rotundus. Afalon and Afalon-S were highly phytotoxic to all the vegetables except I. aquatica. Dual, Devrinol and Tok-E at 1.0 kg/ha were recommended for weed control in B. chinensis. Only Devrinol was suitable for use in B. alboglabra.