Abstract: Site-specific herbigation using a linear-move irrigation system equipped with an automated irrigation control system was evaluated in a series of field trials conducted at the University of Idaho Aberdeen Research and Extension Center near Aberdeen, ID. In the first study, the experimental area was divided into site-specific management zones that were randomly assigned herbigation treatments of metolachlor at 0, 1.8, 2.7, or 3.6 kg ai/ha. In a second study, site-specific herbigation treatments of metribuzin at 0, 0.28, 0.42, or 0.56 kg ai/ha were applied. The tests covered a range in system flow rate from 29 to 90% of maximum design flow. Average metolachlor rates applied were within 1, 2, and 4% of the target 1.8, 2.7, and 3.6 kg/ha rates, respectively, and average metribuzin rates were on target at the 0.28 kg/ha rate and within 5 and 2% of the 0.42 and 0.56 kg/ha target rates, respectively. In a third study, potato (Solanum tuberosum) fields were divided into management zones, and low, medium, or high populations of Indian mustard (Brassica juncea) and foxtail millet (Setaria italica) were seeded in each zone. Different rates of a metolachlor plus metribuzin mixture were herbigated in each zone—higher rates in zones with high populations and lower rates in zones with low populations. Weed control was excellent in all zones. Results suggest good potential for site-specific herbigation when linear-move or center-pivot irrigation systems are equipped with the automated irrigation control system.
Nomenclature: Metolachlor, 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide; metribuzin, 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5-(4H)-one; Indian mustard, Brassica juncea (L.) Czern. et Coss. #3 BRSJU ‘Common Brown’; foxtail millet, Setaria italica (L.) Beauv. # SETIT; potato, Solanum tuberosum L. ‘Russet Burbank’ # SOLTU.
Additional index words: Chemigation, herbicide application, precision agriculture, variable-rate application technology, Chenopodium album, Amaranthus retroflexus, AMARE, CHEAL.
Abbreviations: CV, coefficient of variation; DF, dry flowable; EC, emulsifiable concentrate.