Identifier

etd-03212017-093754

Degree

Master of Science (MS)

Department

Plant, Environmental Management and Soil Sciences

Document Type

Thesis

Abstract

A glasshouse study was conducted on the Louisiana State University campus in Baton Rouge to evaluate herbicide activity on Nealley's sprangletop. Herbicides were applied to Nealley’s sprangletop plants in the one-two tiller stage with height of 20-30 cm. Nealley's sprangletop control, leaf number, height, tiller number, and fresh weight biomass were evaluated. Nealley's sprangletop treated with glyphosate, quizalofop, fenoxaprop, and clethodim was controlled 89 to 99%. A field study was conducted at the LSU AgCenter Rice Research Station (RRS) and a grower location (GL) to evaluate herbicide rates and timings for control of Nealley's sprangletop in drill-seeded rice. Herbicide treatments were cyhalofop at 271, 314, and 417 g ai ha-1 and fenoxaprop at 66, 86, and 122 g ai ha-1 applied pre- or post-flood, propanil at 3360 g ai ha-1 applied pre-flood, and propanil plus thiobencarb at 5040 g ai ha-1 applied pre-flood. Cyhalofop increased control of Nealley's sprangletop compared with control observed with propanil plus thiobencarb. Nealley's sprangletop treated with fenoxaprop at 86 or 122 g ha-1 pre-flood resulted in increased control of Nealley's sprangletop over propanil or propanil plus thiobencarb. Field studies were conducted at the RRS and a GL on drill-seeded rice to evaluate removal timings of Nealley's sprangletop and the impact on rice yield. Fenoxaprop was applied at 122 g ha-1 at 7, 14, 21, 28, 35, and 42 days after emergence (DAE). Rice from the 7 DAE removal yielded 1910 kg ha-1 more than the nontreated. Delaying the initial herbicide application from 7 to 42 DAE caused a rice yield loss of 1790 kg ha-1 with a net loss of $460 ha-1, or $13 ha-1 loss per day. Field studies were conducted at the RRS and a GL in drill-seeded rice to evaluate Nealley's sprangletop infestation densities in rice and the impact on rice yield. Analysis indicated significance for Nealley's sprangletop density on rice yield where the linear effects of density were significant (P < 0.0064). Based on economic evaluations, Nealley's sprangletop at densities of 5 to 10 plants m2 are sufficient threshold levels for treatment.

Date

2017

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Webster, Eric

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