tailieunhanh - Herbicides Environmental Impact Studies and Management Approaches Part 8

Tham khảo tài liệu 'herbicides environmental impact studies and management approaches part 8', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Managing Weeds with Reduced Herbicide Inputs Developing a Novel System for Onion 129 provided greater control than two sequential micro-rate applications averaged over all herbicides data not shown . Some redroot pigweed continued to emerge after the last micro-rate application suggesting that additional micro-rate applications should be considered to control later flushes and may be used to replace a standard bromoxynil plus oxyfluorfen application. Onion injury was not observed the first year but in the second year onion treated with oxyfluorfen displayed approximately 15 injury. These seedling plants one- to two-leaf had leaves that were constricted at the soil surface. Constricted leaves occasionally resulted in onion seedling death but most plants initiated the next true leaf after injury and outgrew the symptoms. Slight injury approximately 5 was noticed from bromoxynil at these locations and all plants outgrew the injury symptoms. Environmental conditions may have contributed to this injury because the average daily temperatures from April to May during the second year were C cooler with numerous cloudy days that may have enhanced herbicide injury. Herbicide Rate Common lambsquarters Redroot pigweed Twoa Three Two Three -- g ha Bromoxynil 18 35c 49 43 66 Bromoxynil 35 60 82 66 89 Bromoxynil 70 92 99 89 97 Oxyfluorfen 18 31 44 38 49 Oxyfluorfen 35 49 71 55 81 Oxyfluorfen 70 69 78 75 95 Metribuzin 5 38 35 34 38 Metribuzin 10 31 41 34 47 Metribuzin 21 38 54 48 63 Acifluorfen 18 32 32 31 44 Acifluorfen 35 30 38 32 54 Acifluorfen 70 43 56 62 76 DCPAb 79 58 Hand weeded 100 100 LSD 13 - - 12 a Two and three refer to the number of applications in the micro-rate system. b Conventional herbicide management check DCPA preemergence at 11 kg ha bromoxynil postemergence at 280 g ha and oxyfluorfen postemergence at 1 120 g ha. c Visual estimates of weed control using a 0 to 100 scale where 0 is equal to no visible control and 100 equal to complete kill. Table 4. .