Effect of temperature and cultivar on the response of broccoli and collard(Brassica oleracea) to oxyfluorfen

Growth chamber studies were conducted to investigate the effect of temperat ure, cultivar, and leaf wax content on the response of broccoli and collard to oxyfluorfen. Broccoli cultivars grown under cool temperatures (15/10 C) were more susceptible to preemergence (PRE) application of oxyfluorfen, an d broccoli and collard cultivars grown at cool temperatures were more susce ptible to postemergence (POST) application of oxyfluorfen than cultivars gr own under warm temperatures (25/20 C). Differences between the tolerant cul tivar 'Pinnacle' and the susceptible cultivar 'Packman' in response to PRE oxyfluorfen application were more distinct at warm temperatures than at coo l temperatures. Although the broccoli and collard cultivars used in the POS T study varied in leaf wax content, differences in wax content did not appe ar to be as important as other genetic factors in the differential response to POST oxyfluorfen application between cultivars.