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Field Validation of Weed Control Recommendations from HERB and SWC Herbicide Recommendation Models

Published online by Cambridge University Press:  12 June 2017

David R. Shaw ,
Alfred Rankins Jr. ,
Jon T. Ruscoe  and
John D. Byrd Jr.
David R. Shaw*
Affiliation:
Department of Plant and Soil Sciences, Mississippi State University, Mississippi State, MS 39762
Alfred Rankins Jr.
Affiliation:
Department of Plant and Soil Sciences, Mississippi State University, Mississippi State, MS 39762
Jon T. Ruscoe
Affiliation:
Department of Plant and Soil Sciences, Mississippi State University, Mississippi State, MS 39762
John D. Byrd Jr.
Affiliation:
Department of Plant and Soil Sciences, Mississippi State University, Mississippi State, MS 39762
*
Address correspondence to David R. Shaw, Mississippi State University, Box 9555, Mississippi State, MS 39762.
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Abstract

Field validation studies were conducted in seven Mississippi environments at three application timings to confirm postemergence (POST) recommendations generated by the computer herbicide decision aids HERB and SWC. HERB and SWC agreed on herbicide treatments in only 14% of the location–application timing combinations. Weed scientists involved in the study agreed on treatment recommendations approximately 33% of the time. The HERB model agreed with a faculty member on only one herbicide treatment, while the SWC model was slightly more agreeable in this regard. Subsequent weed flushes, varied production practices, and delayed weed emergence accounted for a majority of the underestimated predictions given by HERB. Only 55% of the predicted values presented for estimated weed control ratings were similar to actual weed control ratings. Over 75% of the predictions that differed from actual weed control values were underpredictions. Recommendations from both computer models were effective in reducing yield loss below that of the untreated check, and recommendations from the HERB model generally improved yield more than those from the SWC model in most instances. HERB and SWC predictions of yield losses with no weed control were not significantly different from the actual yield loss from the untreated check in nine of the 12 instances at Starkville, seven of the 12 instances at Brooksville, six of the 12 instances at Newton, and three of the six instances at Hollandale. The HERB model estimated yield loss similar to that of the actual yield loss 83% of the time, while predictions from the SWC model were accurate 76% of the time. HERB overestimated yield loss in six of 21 application timing–experiment combinations and underestimated yield loss only once. Yield loss was overpredicted as high as 78%. SWC overpredicted yield loss in five of 21 instances and also underestimated in five instances. SWC did not overpredict yield loss to the same magnitude as HERB in many instances.

Keywords

Soybean, Glycine max (L.) Merr. ‘Northrup King 5960,’‘Terra Vig 5452.’Decision aidmodelCI, competitive indexCL, competitive loadDAE, days after weed emergencefb, followed byPOST, postemergencePPI, preplant incorporatedPRE, preemergenceTCL, total competitive load
Type
Research
Information
Weed Technology , Volume 12 , Issue 1 , March 1998 , pp. 78 - 87
Copyright
Copyright © 1997 by the Weed Science Society of America 

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Footnotes

1

Approved for publication as Journal Article J-8939 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University. This research was a part of state project MIS 2357 and was funded by the Mississippi Soybean Promotion Board. Research was conducted in partial fulfillment of requirements for the M.S. degree in Weed Science at Mississippi State University.

References

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