Weed seed return as influenced by the critical weed-free period in corn (Zea mays L.)

Seed return from later emerging weeds is a concern in weed management syste ms based on critical periods of control. A study in Ontario found that esti mated weed seed return to the soil surface was influenced by the duration o f weed control in corn and the prevailing environmental conditions. Weeds e merging after the 8- to I I-leaf stage of corn growth did not cause an incr ease in total seed number compared to the residual seed bank in the weed-fr ee control.