Management Options and Factors Affecting Control of a Common Waterhemp (Amaranthus rudis) Biotype Resistant to Protoporphyrinogen Oxidase-Inhibiting Herbicides

Dana B Harder,Kelly A Nelson,Reid J Smeda

doi:10.1155/2012/514765

Dana B Harder, Kelly A Nelson + Show 1 more

Open Access

https://doi.org/10.1155/2012/514765

Copy DOI

Abstract

Repeated use of protox-inhibiting herbicides has resulted in a common waterhemp (Amaranthus rudisSauer) biotype that survived lactofen applied up to 10 times the labeled rate. Field and greenhouse research evaluated control options for this biotype of common waterhemp. In the field, PRE applications of flumioxazin at 72 g ai ha−1, sulfentrazone at 240 g ai ha−1, and isoxaflutole at 70 g ai ha−1controlled common waterhemp >90% up to 6 weeks after treatment. POST applications of fomesafen at 330 g ai ha−1, lactofen at 220 g ai ha−1, and acifluorfen at 420 g ai ha−1resulted in <60% visual control of common waterhemp, but differences were detected among herbicides. In the greenhouse, glyphosate was the only herbicide that controlled protox resistant waterhemp. The majority of herbicide activity from POST flumioxazin, fomesafen, acifluorfen, and lactofen was from foliar placement, but control was less than 40% regardless of placement. Control of common waterhemp seeded at weekly intervals after herbicide treatment with flumioxazin, fomesafen, sulfentrazone, atrazine, and isoxaflutole exceeded 85% at 0 weeks after herbicide application (WAHA), while control with isoxaflutole was greater than 60% 6 WAHA. PRE and POST options for protox-resistant common waterhemp are available to manage herbicide resistance.

Highlights

Common waterhemp (Amaranthus rudis Sauer) is a problematic weed in corn (Zea mays L.) and soybean
No differences were found in control between the PRE protoxinhibiting herbicides, flumioxazin or sulfentrazone, compared to the hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide isoxaflutole
Control of a biotype of common waterhemp that is resistant to protox herbicides exceeded 84% with PRE applications of flumioxazin, sulfentrazone, and isoxaflutole, and was >90% with POST applications of mesotrione in 2002

Summary

Introduction

Common waterhemp (Amaranthus rudis Sauer) is a problematic weed in corn (Zea mays L.) and soybean Common waterhemp has adapted to a range of growing conditions and crop production systems due to prolific seed production [4,5,6], competitiveness [7,8,9], genetic diversity, and herbicide resistance [10,11,12,13]. As resistant populations became more frequent, a population of common waterhemp exhibited multiple-resistance to both triazine and ALS-inhibiting herbicides [10]. Continuous usage resulted in common waterhemp biotypes resistant to POST applications of acifluorfen and lactofen in Illinois, Missouri, and Kansas [8, 9, 12, 17]. Li et al [17] determined that a resistant biotype of common waterhemp in Missouri required a 44-fold higher rate of lactofen to achieve similar reduction in plant biomass compared to susceptible plants. Over 30% of the fields in Northeast Kansas were reported resistant to a POST application of protox-inhibiting herbicides [12]

Objectives

Methods

Results

Conclusion