Author
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Wiles, Lori |
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Submitted to: Precision Agriculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/12/2008 Publication Date: 3/22/2009 Citation: Wiles, L. 2009. Beyond Patch Spraying: Site-specific Weed Mmanagement With Multiple Herbicides. Precision Agriculture.Publisher Springer Netherlands: ISSN 1385-2256(Print) 1573-1618 (Online); Volume 10, Number 3/June, 2009;pp 277-290 Interpretive Summary: Growers can control weeds with less herbicide using the technology of precision agriculture for patch spraying. They do not spray areas in a field without weeds or with few weeds. A single herbicide is used on the rest of the field. Some growers do not like this technique compared to spraying the entire field, however, because weeds in the unsprayed areas can produce large quantities of seeds. Technology of precision agriculture has advanced so growers can now spray two or more herbicides in a single trip across a field. We did computer simulations to investigate the value of patch spraying with two or more herbicides in 16 irrigated corn fields of eastern Colorado. Compared to patch spraying with a single herbicide, using two herbicides increased net return by $5.39 ha-1 with just 4% more of the field treated. Although 30% of the field was left unsprayed with two herbicides, weed control was better than spraying the entire field in ten fields. The benefits of using more than two herbicides in a field were small compared to the increase in herbicide use. With the improved weed control, more growers may be willing to adopt patch spraying to reduce herbicide use if more than one herbicide is used in a field. Technical Abstract: Site-specific weed management can include both limiting herbicide to areas of the field where weed pressure is above the economic threshold (patch spraying) and varying the choice of herbicide for most cost-effective weed control of local populations. The benefits of patch spraying with multiple, postemergence herbicides in irrigated corn was evaluated in simulation studies using weed counts from 16 fields. Patch spraying with one, two or the number of herbicides that maximized net return for a field was simulated. With patch spraying with one herbicide, the average area of a field left untreated was 34.5%. Net return increased $3.09 ha-1 and crop yield decreased by 0.05% of weed-free yield compared to a uniform application Patch spraying with two herbicides increased net return to $8.43 ha-1 with just 4% more of the field treated. Weed control was better in 10 fields and herbicide use was reduced in 12 fields compared to a uniform application. More than two herbicides for patch spraying had small benefits compared to the increase in herbicide use. Growers may be more willing to adopt patch spraying if more than one herbicide is used in a field. Limiting the number of herbicides in field to two simplifies the complex task choosing the appropriate herbicide for a field, but a grower concerned about leaving weeds in a field may prefer to use more than two herbicides. |
