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Accepted manuscript

Critical Period for Italian ryegrass (Lolium perenne L. spp. multiflorum) Control in Winter Wheat in North Carolina

Published online by Cambridge University Press:  13 January 2025

Diego J. Contreras Open the ORCID record for Diego J. Contreras [Opens in a new window] ,
Ramon G. Leon Open the ORCID record for Ramon G. Leon [Opens in a new window] ,
Angela R. Post Open the ORCID record for Angela R. Post [Opens in a new window]  and
Wesley J. Everman Open the ORCID record for Wesley J. Everman [Opens in a new window]
Diego J. Contreras*
Affiliation:
Research Assistant, North Carolina State University, Raleigh, NC, USA
Ramon G. Leon
Affiliation:
William Neal Reynolds Distinguished Professor and University Faculty Scholar, North Carolina State University, Raleigh, NC, USA
Angela R. Post
Affiliation:
Associate Professor, North Carolina State University, Raleigh, NC, USA
Wesley J. Everman
Affiliation:
Professor, North Carolina State University, Raleigh, NC, USA.
*
Author for correspondence: Diego Contreras, Research Assistant, North Carolina State University, Williams Hall, 101 Derieux Pl, Raleigh, NC, 27607. Email: djcontre@ncsu.edu
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Abstract

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Field studies were conducted in North Carolina to determine the critical period of weed control (CPWC) for Italian ryegrass in winter wheat. Soft red winter wheat was planted in late fall in 2017 and 2018 in no-till fields near Salisbury, NC. Treatments consisted of allowing weeds to grow from crop emergence for different intervals until removal (“weedy”), maintaining “weed-free” conditions from crop emergence for the same intervals, and then letting the weeds emerge and compete with the crop for the duration of the season. In 2017, weed removal occurred in two-week intervals from crop emergence up to 18 weeks after crop emergence (WAE) and three-week intervals up to 18 WAE in 2018. Additional biological measurements, including Italian ryegrass density and height, were collected at 6, 12, and 18 WAE to characterize the effect of crop-weed interactions on the CPWC and weed populations. Non-linear regression analysis was conducted to relate the timing of weed removal and yield loss. The analysis was done using growing degree days (GDD) accumulated at corresponding WAE. Italian ryegrass density ranged from 292 to 824 plants m-2, which created intense competitive conditions with wheat. In the absence of weed control, yield loss surpassed 60%. Using 5% yield loss as an accepted threshold, the CPWC for Italian ryegrass in no-till planted wheat was estimated to be from 1100 to 1900 GDD. This relatively short period makes it possible to reduce weed control intensity if control actions are properly timed.

Keywords

weed managementyield lossthresholdcultural practices
Type
Research Article
Information
Weed Technology , Accepted manuscript , pp. 1 - 16
Creative Commons
Creative Common License - CCCreative Common License - BYCreative Common License - NCCreative Common License - ND
This is an Open Access article, distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives licence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is unaltered and is properly cited. The written permission of Cambridge University Press must be obtained for commercial re-use or in order to create a derivative work.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Weed Science Society of America