Investigations of Field Performance and Physiological Effects of Metsulfuron and Metsulfuron Combinations on Field Bindweed (Convolvulus arvensis L.)

Field bindweed (Convolvulus arvensis L.) is a noxious perennial weed of many fallow and cropland fields all over the world. Present control methods are not satisfactory for field bindweed. Metsulfuron, 2[[[[(4-methoxy-6-methyl-1,3,5-triazine-2-yl) amino] carbonyl] amino] sulfonyl] benzoic acid, is a new herbicide that has been shown to have activity on bindweed especially when tank mixed with other herbicides. This study was conducted to investigate the field performance and some physiological effects of metsulfuron on field bindweed. Neither metsulfuron alone nor metsulfuron combinations gave persistent control of field bindweed. Metsulfuron usually increased the activity of other bindweed herbicides. Herbicide application to field bindweed in the full bloom growth stage did not control the weed as well as the same treatments in the prebloom growth stages and treating regrowth the fall after tilling bindweed in full blossom. Application of metsulfuron at full bloom decreased seed weight, seed size seed viability and seedling vigor of field bindweed but did not alter seed set. Metsulfuron at 23 g/ha and above caused unacceptable injury to barley (Hordeum vulgaris L.) and oats (Avena sativa L.). Higher rates of metsulfuron resulted in greater phytotoxicity. Metsulfuron stopped photosynthesis of field bindweed within two weeks regardless of herbicide dosage used. Field bindweed seedlings were observed growing in the field under light intensities of 28 to 62 μmoles m-2 s-1 which was below the light compensation point obtained for greenhouse grown bindweed plants (about 65 μmoles m-2 s-1). Higher quantities of 14C labelled metsulfuron per mg plant dry weight were recovered in the above treated leaf sections than in any other parts of bindweed plants. Metsulfuron applied as a foliage spray two days prior to administering 14C metsulfuron significantly increased absorption to the radiolabelled herbicide in field bindweed plants.