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Common Waterhemp Growth and Fecundity as Influenced by Emergence Date and Competing Crop

Permanent URL:
http://handle.nal.usda.gov/10113/13205
File:
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Abstract:
Common waterhemp (Amarathus rudis Sauer) is a frequent weed in glyphosate-resistant (GR) crops in the midwestern USA due, in part, to the delayed emergence of its seedlings. Variable waterhemp emergence was simulated by transplanting seedlings into both corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] and bare plot areas at differing crop growth stages during two growing seasons in western Minnesota. Growth and fecundity were measured. As expected, late planted weeds produced little dry matter and few seeds, and competition from corn or soybean reduced waterhemp dry weight and fecundity by >or= 90% compared with isolated plants. Interestingly, common waterhemp was affected differently by crop and transplanting date. Common waterhemp grown with corn was always shaded by the crop canopy but produced seeds even when transplanted as late as the V10 growth stage. In soybean, weeds transplanted before the V4 growth stage were taller than soybean and produced more seeds than those transplanted into corn at a comparable growth stage; however, those transplanted after V5 produced no seeds. Consequently, control of late-emerging common waterhemp plants in soybean may not be needed, whereas control of late-emerging plants in corn may be justified because of relatively high levels of seed production.
Author(s):
Uscanga-Mortera, E. , Clay, S.A. , Forcella, F. , Gunsolus, J.
Subject(s):
Zea mays , corn , grain crops , Glycine max , soybeans , Amaranthus , broadleaf weeds , seedling emergence , phenology , crop-weed competition , seed productivity , plant growth , dry matter accumulation , shade , height , weed control , integrated weed management , Minnesota
Format:
p. 1265-1270.
Note:
Includes references
Source:
Agronomy journal 2007 Sept-Oct, v. 99, no. 5
Language:
English
Year:
2007
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.