Objective:
The objectives of the research are to test for residual effects of five soil active herbicides on six crop species and a variety of agricultural weeds at three locations in Alaska. In addition the study will determine herbicidal response of these six crops to known doses of these herbicides in the field.

Approach:
Part 1 – Residual effects of five soil active herbicides Three sites – UAF Expt. Farms at Fairbanks, Delta Junction, and Palmer. Study to begin in May 2011 and end in September 2015 Six treatments – control, Chlorsulfuron (17.5 g ai/ha), Metsulfuron (4.2 g ai/ha), Dicamba (0.56 kg ae/ha), Clopyralid (0.56 kg ae/ha), Aminopyralid (123 g ae/ha) will be applied in the summer of 2011 to bare ground. Crops – Barley, Canola, Potato, Lettuce, Carrot, Kale, (others crops to be decided) and no crop will be planted in 6 ft wide strips through the plot starting in 2012. There is space for additional crops. Plot size – 30 x 42 ft Barley Canola Potato Lettuce Carrot Kale No Crop Experimental design– RCD with 4 replications at each site and 20 ft alleyways between plots Study area is 180 x 352 ft, crops may get some water. Herbicide sampling will occur before and multiple times after treatment at three depths. Weed and crop response will be measured each year and experiment will end when all crop growth is equal to control plots. Weed injury measures will begin in 2011 (autumn cover measures), crop injury measures will begin in 2011 three weeks after crops are planted and at harvest. Tolerant weeds will be controlled with tillage or other post-emergence herbicide. Measures will continue yearly until crop injury is not detected. Part 2 – Dose response study for soil active herbicides The same sites and herbicides as in Part 1 will be used in part 2. Crops will be planted perpendicular to strips of herbicide applied at a variety of rates. Study to begin in May 2011 and end in September 2012. Plot size – 6 x 30 ft (below is diagram of a plot of one replication of chlorsulfuron treatments). There will be 2 ft between every herbicide application (plot area will be 30 x 26 feet) 1X chlorsulfuron 0.5X chlorsulfuron 0.25X chlorsulfuron 0.125X chlorsulfuron 0.062x chlorsulfuron No herbicide Again this will be set up as a RCB with 4 replications. Study area will be 130 x 158 ft This study will be set up and sprayed early in 2011, with crop planted immediately after spraying. Herbicide injury to weeds and crops will be measured about 3 wk after treatment and at harvest. The study will be repeated in 2012.