Control of multiple-resistant Palmer amaranth populations in corn will rely heavily on the use of POST 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides. Therefore, field and greenhouse experiments were conducted to: (1) evaluate Palmer amaranth control with four HPPD inhibitors alone and in combination with atrazine at two application timings and (2) investigate the joint activity of HPPD-inhibiting herbicides and atrazine in atrazine-resistant (AR) and atrazine-susceptible (AS) Palmer amaranth populations. Control of the AR Palmer amaranth population varied among the HPPD-inhibiting herbicides with tolpyralate>tembotrione=topramezone>mesotrione based on GR50 values in the greenhouse. In the field, Palmer amaranth control was lower when the HPPD-inhibiting herbicides, with the exception of tolpyralate, were applied to 15- vs. 8-cm-tall Palmer amaranth. Tolpyralate controlled Palmer amaranth ≥95% at both application timings. The addition of atrazine (560 g ai ha−1) improved Palmer amaranth control with mesotrione and topramezone at the 8-cm application timing and with mesotrione and tembotrione at the 15-cm application timing. In the greenhouse, joint activity of mesotrione and atrazine and tembotrione and atrazine was synergistic with both the AR and AS Palmer amaranth populations. In the AR population, an additional 980 g ai ha−1 of atrazine (8X) was needed to cause a synergistic response compared with the AS population. Synergistic responses with mesotrione were detected with all atrazine rates for the AS population and for atrazine rates ranging from 280 to 2,240 g ai ha−1 for the AR population. Only additive responses were observed when atrazine was applied with tolpyralate and topramezone, indicating that joint activity in the form of synergism occurs more readily with the triketones compared with the benzopyrazoles. When faced with an AR Palmer amaranth population, the addition of atrazine to HPPD inhibitors may increase the overall success of weed management due to joint activity.

Teamwork in the maritime traffic system has been identified as an area of concern, and reports suggest there is room for improvement. Such improvements should be based on an understanding of how everyday activities are performed. This study was therefore aimed at gaining an insight into the everyday activity of navigating and manoeuvring ships in port waters. To get such an insight, the perceptions of ship masters, maritime pilots, tug masters and Vessel Traffic Service operators active in Australia were probed through qualitative research interviews. A conceptual framework based on Clark's work on joint activity was used to guide the study. Results indicate that in order to get the job done, these maritime professionals employ tools and procedures beyond those intended to be used, vary their level of participation, assume roles which differ from those prescribed, sometimes base their assumptions and expectations on poor quality evidence, and occasionally avoid communication. While such adaptations may be necessary to get the job done, they also reduce the participants’ ability to establish common ground – which is essential for coordination.