Tolerance of corn to PRE- and POST-applied photosystem II–inhibiting herbicides

Jacob T Richburg,Trent L Roberts,Jason K Norsworthy,Tom Barber,Edward E Gbur

doi:10.1017/wet.2019.119

Jacob T Richburg, Trent L Roberts + Show 3 more

Open Access

https://doi.org/10.1017/wet.2019.119

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Journal: Weed Technology	Publication Date: Nov 14, 2019
Citations: 3	License type: CC BY 4.0

Affiliation: University of Arkansas at Fayetteville

Abstract

AbstractWeed control in corn traditionally has relied on atrazine as a foundational tool to control problematic weeds. However, the recent discovery of atrazine in aquifers and other water sources increases the likelihood of more strict restrictions on its use. Field-based research trials to find atrazine alternatives were conducted in 2017 and 2018 in Fayetteville, AR, by testing the tolerance of corn to PRE and POST applications of different photosystem II (PSII) inhibitors alone or in combination with mesotrione or S-metolachlor. All experiments were designed as a two-factor factorial, randomized complete block, with the two factors being (1) PSII-inhibiting herbicide and (2) the herbicide added to create the mixture. The PSII-inhibiting herbicides were prometryn, ametryn, simazine, fluometuron, metribuzin, linuron, diuron, atrazine, and propazine. The second factor consisted of either no additional herbicide, S-metolachlor, or mesotrione. Treatments were applied immediately after planting in the PRE experiments and to 30-cm–tall corn for the POST experiments. For the PRE study, low levels of injury (<15%) were observed at 14 and 28 d after application and corn height was negatively affected by the PSII-inhibiting herbicide applied. PRE-applied fluometuron- and ametryn-containing treatments consistently caused injury to corn, often exceeding 5%. Because of low injury levels caused by all treatments, crop density and yield did not differ from that of the nontreated plants. For the POST study, crop injury, relative height, and relative yield were affected by PSII-inhibiting herbicide and the herbicide added. Ametryn-, diuron-, linuron-, propazine-, and prometryn-containing treatments caused at least 25% injury to corn in at least 1 site-year. All PSII-inhibiting herbicides, except metribuzin and simazine when applied alone, caused yield loss in corn when compared with atrazine alone. Diuron-, linuron-, metribuzin-, and simazine-containing treatments applied PRE and metribuzin- and simazine-containing treatments applied POST should be investigated further as atrazine replacements.

Highlights

Weed control is a necessity for corn producers because poor weed control can negatively affect yields
We tested the tolerance of corn to the aforementioned photosystem II (PSII)-inhibiting herbicides alone and in combination with mesotrione and S-metolachlor to determine their potential as replacements for atrazine
Given that both experiments were conducted on the same soil texture, with similar organic matter and pH, it is likely that any differences in herbicide performance depended on rainfall timing and rate after herbicide application

Summary

Introduction

Weed control is a necessity for corn producers because poor weed control can negatively affect yields. Several of these PSII-inhibiting herbicides, including diuron, linuron, metribuzin, and propazine, are generally applied to crops for residual weed control at lower rates than used for atrazine (Shaner 2014). We tested the tolerance of corn to the aforementioned PSII-inhibiting herbicides alone and in combination with mesotrione and S-metolachlor to determine their potential as replacements for atrazine.

Results

Conclusion