Late-Season Weed Escape Survey Reveals Discontinued Atrazine Use Associated with Greater Abundance of Broadleaf Weeds

Atrazine has been used for control of many weeds, primarily broadleaf weeds, in U.S. corn fields since 1957. Recently, the adoption of glyphosate-resistant corn hybrids have led to glyphosate eclipsing atrazine as the most commonly used herbicide in corn production. However, the evolution and spread...

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Bibliographic Details
Published in:Weed technology 2015-07, Vol.29 (3), p.451-463
Main Authors: Recker, Ross A, Mitchell, Paul D, Stoltenberg, David E, Lauer, Joseph G, Davis, Vince M
Format: Article
Language:English
Subjects:
Agriculture
Amaranthus
Atrazine
Binding sites
Community composition
Corn
Crop production
Crops
Drinking water
glyphosate resistance
herbicide resistance
Herbicides
Hybrids
Polls & surveys
Relative abundance
Water wells
Weed community composition
WEED MANAGEMENT—MAJOR CROPS
Weeds
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Summary:Atrazine has been used for control of many weeds, primarily broadleaf weeds, in U.S. corn fields since 1957. Recently, the adoption of glyphosate-resistant corn hybrids have led to glyphosate eclipsing atrazine as the most commonly used herbicide in corn production. However, the evolution and spread of glyphosate-resistant weeds is a major concern. Atrazine use in Wisconsin is prohibited in 102 areas encompassing 0.49 million ha where total chlorinated residues were found in drinking water wells at concentrations > 3 μg L−1. Atrazine has been prohibited in many of those areas for > 10 yr, providing an opportunity to evaluate weed community composition differences due to herbicide regulation. In question, has the abundance of broadleaf weeds increased, coupled with an increased reliance on glyphosate, where atrazine use has been discontinued? To answer this, an online questionnaire was distributed to Wisconsin growers in June and then weeds present in 343 fields in late July through mid-September in 2012 and 2013 were counted. Data were summarized for frequency, uniformity, density, and relative abundance to compare weed community composition in fields with discontinued vs. recent atrazine use. Growers used glyphosate in 70 vs. 54% of fields with discontinued vs. recent atrazine use, respectively (P = 0.021). Moreover, broadleaf weeds were found more frequently, (73 vs. 61%; P = 0.03), they had 50% greater in-field uniformity (P = 0.002), and density was 0.4 vs. 0.19 plants m−2 (i.e., twofold greater; P 
ISSN:0890-037X
1550-2740
DOI:10.1614/WT-D-14-00122.1