@article{wilkerson_price_bennett_krueger_roberson_robinson_2004, title={Evaluating the potential for site-specific herbicide application in soybean}, volume={18}, ISSN={["0890-037X"]}, DOI={10.1614/WT-03-258R}, abstractNote={Field experiments were conducted on two North Carolina research stations in 1999, 2000, and 2001; on-farm in Lenoir, Wayne, and Wilson counties, NC, in 2002; and on-farm in Port Royal, VA, in 2000, 2001, and 2002 to evaluate possible gains from site-specific herbicide applications at these locations. Fields were scouted for weed populations using custom software on a handheld computer linked to a Global Positioning System. Scouts generated field-specific sampling grids and recorded weed density information for each grid cell. The decision aid HADSS™ (Herbicide Application Decision Support System) was used to estimate expected net return and yield loss remaining after treatment in each sample grid of every field under differing assumptions of weed size and soil moisture conditions, assuming the field was planted with either conventional or glyphosate-resistant (GR) soybean. The optimal whole-field treatment (that treatment with the highest expected net return summed across all grid cells within a field) resulted in average theoretical net returns of $79/ha (U.S. dollars) and $139/ha for conventional and GR soybean, respectively. When the most economical treatment for each grid cell was used in site-specific weed management, theoretical net returns increased by $13/ha (conventional) and $4.50/ha (GR), and expected yield loss after treatment was reduced by 10.5 and 4%, respectively, compared with the whole-field optimal treatment. When the most effective treatment for each grid cell was used in site-specific weed management, theoretical net returns decreased by $18/ha (conventional) and $4/ha (GR), and expected yield loss after treatment was reduced by 27 and 19%, respectively, compared with the whole-field optimal treatment. Site-specific herbicide applications could have reduced the volume of herbicides sprayed by as much as 70% in some situations but increased herbicide amounts in others. On average, the whole-field treatment was optimal in terms of net return for only 35% (conventional) and 57% (GR) of grid cells.}, number={4}, journal={WEED TECHNOLOGY}, author={Wilkerson, GG and Price, AJ and Bennett, AC and Krueger, DW and Roberson, GT and Robinson, BL}, year={2004}, pages={1101–1110} }
 @article{jordan_wilkerson_krueger_2003, title={Evaluation of scouting methods in peanut (Arachis hypogaea) using theoretical net returns from HADSS (TM)}, volume={17}, ISSN={["1550-2740"]}, DOI={10.1614/0890-037X(2003)017[0358:EOSMIP]2.0.CO;2}, abstractNote={A perceived limitation to incorporating herbicide application decision support system (HADSS™) into routine peanut weed management decisions is efficient scouting of fields. A total of 52 peanut fields were scouted from 1997 through 2001 in North Carolina to determine the weed density in a 9.3-m2 section for each 0.4-ha grid of the field. These weed populations and their spatial distributions were used to compare theoretical net return (TNR) over herbicide investment for various scouting methods and weed management approaches. HADSS was used to determine the expected net return for each treatment in each 0.4-ha section of every field under differing assumptions of weed size, soil moisture conditions, and pricing structures. The treatment with the highest net return averaged across all 0.4-ha grids was considered to be the optimal whole-field treatment. For all 52 fields, TNR for the best whole-field treatment and for site-specific weed management (applying the most economical recommendation on each 0.4-ha grid) averaged $414 and $435/ha, respectively. Estimated return from the commercial postemergence herbicide program of aciflurofen plus bentazon plus 2,4-DB followed by clethodim (where grass was present) averaged $316/ha across all 52 fields. For fields of 5 ha or more (17 fields) in which 12 or more samples were taken, TNR was $500, $510, and $516/ha for three-sample (one pass through the middle of the field with samples taken on both ends and the center of the field), six-sample (two passes through the field with three stops per pass), and full-sample (one stop for each 0.4 ha) approaches, respectively.Nomenclature: Peanut, Arachis hypogaea L.Additional index words: Economic thresholds, prescription weed management, weed interference, weed scouting, weed thresholds.Abbreviations: HADSS, herbicide application decision support system; TNR, theoretical net return over herbicide investment.}, number={2}, journal={WEED TECHNOLOGY}, author={Jordan, DL and Wilkerson, GG and Krueger, DW}, year={2003}, pages={358–365} }
 @article{krueger_wilkerson_coble_gold_2000, title={An economic analysis of binomial sampling for weed scouting}, volume={48}, ISSN={["1550-2759"]}, DOI={10.1614/0043-1745(2000)048[0053:AEAOBS]2.0.CO;2}, abstractNote={Full-count random sampling has been the traditional method of obtaining weed densities. Currently it is the recommended scouting procedure when using HERB, a herbicide selection decision aid. However, alternative methods of scouting that are quicker and more economical need to be investigated. One possibility that has been considered is binomial sampling. Binomial sampling is the procedure by which density is estimated from the number of random quadrats in which the count of individuals is equal to or less than a specified cutoff value. This sampling method has been widely used for insect scouting. There has also been interest in using binomial sampling for weed scouting. However, an economic analysis of this sampling method for weeds has not been performed. In this paper, the results of an economic analysis using simulations with binomial sampling and the HERB model are presented. Full-count sampling was included in the simulations to provide a benchmark for comparison. The comparison was made in terms of economic losses incurred when the estimated weed density obtained from sampling was inaccurate and a herbicide treatment was selected that did not maximize profits. These types of losses are referred to as opportunity losses. The opportunity losses obtained from the simulations indicate that in some situations binomial sampling may be a viable economic alternative to full-count sampling for fields with weed populations that follow a negative binomial distribution, assuming no prior knowledge of weed densities or negative binomial k values.}, number={1}, journal={WEED SCIENCE}, author={Krueger, DW and Wilkerson, GG and Coble, HD and Gold, HJ}, year={2000}, pages={53–60} }