Author
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Wiles, Lori |
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Submitted to: Weed Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/24/2004 Publication Date: 1/20/2005 Citation: Wiles, L. 2005. Sampling to make maps for site-specific weed management. Weed Science. 53:228-235 Interpretive Summary: Herbicide use may be reduced with site-specific weed management. Growers could spray weed patches rather than entire fields and treat each patch with the most appropriate herbicide, but first scientists must develop cost-effective sampling plans to map weeds in a field. Sampling plans prescribe where and how to observe a pest for a management decision. Methods for designing sampling plans to decide whether to apply insecticide to a field have been developed, but other methods are needed for sampling for site-specific weed management. We have learned how sampling must differ from studies of weed patches in fields and the cost of identifying and counting weed seedlings and seeds, plus interviews with growers about how they decide to manage weeds in a field. Weed scientists must develop plans that prescribe how to make a map in addition to how to sample and should evaluate plans based on predicted profit, herbicide use and weeds left in the field with prescribed site-specific management rather than accuracy of the weed map. Costly observations must be minimized by substituting other information such as aerial photographs, weed maps from prior years, and the grower's perception of patches in a field. In general, weed scientists will be most effective in designing sampling plans for site-specific weed management by studying methods to sample soil for management rather than pests. Technical Abstract: Growers need affordable methods to map weed populations to reduce herbicide use with site-specific weed management. The paradigm for designing cost-effective sampling plans from integrated pest management is not sufficient for site-specific weed management because a map, rather than an estimate of average pest population in a field, is needed. Foremost, sampling must be thought of as a process over time that uses many types of information rather than a single event of collecting one type of information. Further, methods to make maps must be recommended as part of a sampling plan. Developing cost effective plans will be challenging. Weed scientists will need to identify common characteristics of the spatial distribution of weeds among fields and species; know more about the spatial dynamics of weed populations; and assess plans based on the usefulness of the site-specific prescription. Growers' knowledge of the distribution of weeds and past spatially variable management within a field may become as important as observations of the weed population for cost'effective mapping. A critical task will be demonstrating to growers that site-specific weed management will be cost-effective with methods developed. |
