RATE AND TIME OF BENTAZON ATRAZINE APPLICATION FOR BROADLEAF WEED-CONTROL IN CORN (ZEA-MAYS)/

The effects of herbicide-adjuvant combinations and times of applicatio n on weed density and corn yield were determined in a 3-yr field study . At a given rate and time of application of bentazon/atrazine, Assist and Merge were equally effective adjuvants. Assist would be the adjuv ant of choice for bentazon/atrazine rather than Merge because of its c urrently lower cost. Weed density depended on the rate and time of app lication of bentazon/atrazine. In general, bentazon/atrazine applied a t early stages (7 d after emergence) of the development of corn seedli ngs or at high or intermediate rate (1.6 or 0.8 kg ai/ha) maintained l ow weed densities, with a relatively small range of variation over yea rs. Delay in time (14 or 21 d after emergence) or reduction in herbici de rate (0.4 kg ai/ha) increased the risk of high weed pressure, altho ugh it was not always associated with yield loss. The best time for th e application of postemergence herbicide appears to be a few days prio r to the onset of the critical period of weed control.