RESPONSE OF VARIOUS BROAD-LEAVED WEEDS, AND TOLERANCE OF CEREALS, TO SOIL AND FOLIAR APPLICATIONS OF DPX-4189

Abstract

DPX-4189 (2-chloro-N-[4-methoxy-6-methyl-1,3,5-triazin-2-yl) amino-carbonyl]-benzenesulfonamide), applied at relatively low rates to the soil (40–200 g/ha) or foliage (1–100 g/ha), generally provided excellent control of a variety of broad-leaved weeds, but poor control of green foxtail (Setaria viridis (L.) Beauv.). Wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) showed excellent tolerence. At equivalent dosages, foliar applications were more effective than soil applications in the year of application. With foliar applications, herbicidal activity on a variety of annual broad-leaved weed species was reduced with application at later (four to eight) versus earlier (two to four) leaf stages. Preplant incorporated (PPI) treatments were more effective for control of Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) than soil surface (PE) or preemergence incorporated (PEI) treatments. DPX-4189 provided weed control 8 mo after application at 20 g/ha in the greenhouse and 12 mo after application at 40 g/ha in the field. Canada thistle (Cirsium arvense (L.) Scop.) topgrowth control during the year of application, and control of regrowth 1 yr after application of DPX-4189 at 50 g/ha under field conditions was excellent. DPX-4189 may be transported from the leaves to the roots of Canada thistle, but soil residue carryover is probably more important for control during the second year. DPX-4189 was readily leached in a silt-loam soil.