Palmer Amaranth (Amaranthus palmeri) Growth and Seed Production When in Competition with Peanut and Other Crops in North Carolina

Denis J Mahoney,Andrew T Hare,Wesley J Everman,Ramon G Leon,Charles W Cahoon,Nilda Roma-Burgos,David L Jordan,Matthew C Vann,Katherine M Jennings

doi:10.3390/agronomy11091734

Denis J Mahoney, Andrew T Hare + Show 7 more

Open Access

https://doi.org/10.3390/agronomy11091734

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Abstract

Palmer amaranth (Amaranthus palmeri S. Wats.) is a highly competitive weed that can be difficult to manage in many cropping systems. Research to date has not quantified the growth and development of A. palmeri in a manner that allows direct comparisons across cropping systems. Research was conducted to compare the growth, development, and seed production of A. palmeri when competing with corn (Zea mays L.), cotton (Gossypium hirsutum L.), peanut (Arachis hypogaea L.), and soybean [Glycine max (L.) Merr.] when emerging with crops or emerging three weeks after crops emerge. Regardless of when A. palmeri emerged, seed production was greatest and similar in cotton and peanut and exceeded that of corn and soybean; seed production in soybean exceeded that of corn. However, seed production was approximately 10-fold greater when A. palmeri emerged with crops compared with emergence three weeks later. These results illustrate the importance of controlling weeds during the first three weeks of the season relative to contributions of A. palmeri to the weed seed bank and is the first report comparing seed production in presence of these crops in a manner allowing a statistical comparison of seed production and highlighting the importance of crop sequence for seed bank management.

Highlights

IntroductionWats.) is regarded as one of the most problematic weeds in the United States [1]
Timely herbicide applications are needed to control this weed if a residual herbicide was not applied
Amaranthus palmeri was 10 cm in height approximately 17 to 18 d after it emerged with corn, cotton, peanut, or soybean

Summary

Introduction

Wats.) is regarded as one of the most problematic weeds in the United States [1]. It possesses robust growth habits [2,3] and has been shown to effectively compete against crops for nutrients [4], light [5], and water [6]. Amaranthus palmeri is an obligate cross-pollinator, which contributes to its high genetic variation [7]. Its pollen can move long distances [8]. Along with immense herbicide selection pressure, these characteristics have led to A. palmeri populations having resistance to several mechanisms of action with some populations expressing multiple resistance [9,10]

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