Semester of Graduation

Spring 2018

Degree

Master of Science (MS)

Department

The Department of Plant, Environmental, and Soil Science

Document Type

Thesis

Abstract

ABSTRACT

Research was conducted at the LSU AgCenter Dean Lee Research and Extension center near Alexandria, La in 2016 and 2017 to evaluate the growth characteristics and control of Nealley’s sprangletop. Nealley’s sprangletop is a relatively new weed with little research available to understand its growth habit and effective control strategies.

Nealley’s sprangletop undergoes a more drastic height increase of 212 to 742 mm, 4 to 6 WAE than Amazon sprangletop 377 to 612 mm in the same time frame. Averaged across harvest interval tiller and leaf number of Nealley’s sprangletop was approximately 50 and 40% less than Amazon sprangletop. Nealley’s sprangletop reached a maximum LAR 4 WAE of 52.2 cm2 g-1at the same harvest interval Amazon sprangletop LAR was 91.5 cm2 g-1, which may be a function of lesser photosynthetic capacity. Amazon sprangletop NAR was greater than Nealley’s sprangletop 4 to 6 WAE with 30 g cm2 d-1 compared with 12.9 g cm2 d-1, respectively. There were no differences for RGR between the two species, however SLA, a major contributor to RGR yielded differences. Averaged across harvest interval Amazon sprangletop SLA was 157.2 cm2 g-1 which was greater than Nealley’s sprangletop at 112.9 cm2 g-1. The lowest SLR coincided with the highest LAR harvest interval at 4 WAE harvest interval, indicating the period in which plant growth is most rapid regardless of species. There were no differences between Amazon and Nealley’s sprangletop SLW.

All glyphosate based applications initialized at 10 cm were greater than 94% control 28 DAT. When treatments were delayed to 31 cm Nealley’s sprangletop, the addition of graminicides increased control >94% 28 DAT. Glufosinate applied alone failed to control Nealley’s sprangletop at 10 or 31 cm timings regardless of the addition of sequential applications. Quizalofop co-applied with glufosinate to 10 cm resulted in 95% control 28 DAT, however was ineffective at 31 cm timing with 77% control 28 DAT with a single application. Clethodim or quizalofop co-applied with glufosinate in sequential applications resulted in 86 and 98% control 21 DAT compared to 77% by glufosinate alone at 31 cm Nealley’s sprangletop.


Date

3-26-2018

Committee Chair

Webster, Eric

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