No studies have been conducted to explore the influence of stress caused by uncontrolled weeds on traits associated with drought tolerance. Two hypotheses were tested: 1) Delaying weed control would lengthen the anthesis-silking interval (ASI) in both a drought tolerant and non-drought tolerant maize hybrid and 2) The presence of drought tolerance genetics comes at a physiological cost, resulting in greater yield reductions under weedy conditions. Field studies were conducted to compare the response of a drought tolerant hybrid with its non-drought tolerant near-isoline to seven weed control timings. There was no treatment by hybrid interaction at any site-year for any parameters evaluated. Delaying weed control reduced height, leaf number, biomass, kernel number and grain yield and lengthened ASI for both hybrids. The drought tolerant hybrid had a shorter ASI, a lower kernel number and higher kernel weight. No yield differences were observed between hybrids at any weed control timing. / Natural Science and Engineering Research Council of Canada (File CRDPJ 425128-11), Syngenta Crop Protection Inc. and Ontario Ministry of Agriculture, Food, and Rural Affairs