Tools for Improved Management of Buffelgrass in the Sonoran Desert

Persistent Link:
http://hdl.handle.net/10150/325503
Title:
Tools for Improved Management of Buffelgrass in the Sonoran Desert
Author:
Bean, Travis M.
Issue Date:
2014
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Embargo:
Release 1-Aug-2015
Abstract:
Buffelgrass (Cenchrus ciliaris L.) is an invasive, perennial, C₄ bunchgrass. Buffelgrass has a rapid invasion rate, a tendency to displace native vegetation, and presents a fire risk to native plant communities, adjacent developed areas and their associated infrastructure. Mechanical control is impractical and unable to keep pace with regional spread. Chemical control has offered the most promise for successful and cost-effective management on a regional scale. The predominant herbicide used to control buffelgrass is glyphosate, which requires active vegetative growth when applied for optimum uptake and translocation to meristematic tissue. The timing and duration of active growth is difficult to predict. In this dissertation I addressed three related topics to improve effectiveness of buffelgrass management in the Sonoran Desert. First, I used digital time-lapse photography and weather data to predict the timing and length of future active growth based on day of year and antecedent weather at three sites in the Sonoran Desert near Tucson, AZ that were representative of habitats currently infested by buffelgrass in the region. I was able to correctly predict greenness above or below a threshold of herbicide susceptibility at 81 to 95% for a basin floor site and at 61-88% for slope sites. Second, I evaluated the effects of different rates of two herbicides (imazapic and clethodim), alone or in combination with different rates of glyphosate, for pre- (imazapic only) and postemergence control of buffelgrass. I found a minimum glyphosate application rate of 2.52 kg ae ha⁻¹ glyphosate consistently killed mature buffelgrass plants; clethodim at had no effect on mature buffelgrass; and imazapyr was successful in killing mature plants when applied during the dormant season at 0.56 kg ae ha⁻¹ and provided preemergence control. Imazapic severely damaged but did not kill mature buffelgrass plants at the maximum label rate of 0.21 kg ae ha⁻¹. Finally, we evaluated results from a helicopter broadcast herbicide application trial conducted in the Tucson Mountains. We demonstrated that most species and life forms were less affected than buffelgrass to glyphosate deposition rates achieved in the study, but asserted that procedural changes were necessary to achieve effective buffelgrass control.
Type:
text; Electronic Dissertation
Keywords:
Cenchrus ciliaris; chemical control; invasive plants; phenology; Natural Resources; aerial herbicide application
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Natural Resources
Degree Grantor:
University of Arizona
Advisor:
Smith, Steven E.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen
dc.titleTools for Improved Management of Buffelgrass in the Sonoran Deserten_US
dc.creatorBean, Travis M.en_US
dc.contributor.authorBean, Travis M.en_US
dc.date.issued2014-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.releaseRelease 1-Aug-2015en_US
dc.description.abstractBuffelgrass (Cenchrus ciliaris L.) is an invasive, perennial, C₄ bunchgrass. Buffelgrass has a rapid invasion rate, a tendency to displace native vegetation, and presents a fire risk to native plant communities, adjacent developed areas and their associated infrastructure. Mechanical control is impractical and unable to keep pace with regional spread. Chemical control has offered the most promise for successful and cost-effective management on a regional scale. The predominant herbicide used to control buffelgrass is glyphosate, which requires active vegetative growth when applied for optimum uptake and translocation to meristematic tissue. The timing and duration of active growth is difficult to predict. In this dissertation I addressed three related topics to improve effectiveness of buffelgrass management in the Sonoran Desert. First, I used digital time-lapse photography and weather data to predict the timing and length of future active growth based on day of year and antecedent weather at three sites in the Sonoran Desert near Tucson, AZ that were representative of habitats currently infested by buffelgrass in the region. I was able to correctly predict greenness above or below a threshold of herbicide susceptibility at 81 to 95% for a basin floor site and at 61-88% for slope sites. Second, I evaluated the effects of different rates of two herbicides (imazapic and clethodim), alone or in combination with different rates of glyphosate, for pre- (imazapic only) and postemergence control of buffelgrass. I found a minimum glyphosate application rate of 2.52 kg ae ha⁻¹ glyphosate consistently killed mature buffelgrass plants; clethodim at had no effect on mature buffelgrass; and imazapyr was successful in killing mature plants when applied during the dormant season at 0.56 kg ae ha⁻¹ and provided preemergence control. Imazapic severely damaged but did not kill mature buffelgrass plants at the maximum label rate of 0.21 kg ae ha⁻¹. Finally, we evaluated results from a helicopter broadcast herbicide application trial conducted in the Tucson Mountains. We demonstrated that most species and life forms were less affected than buffelgrass to glyphosate deposition rates achieved in the study, but asserted that procedural changes were necessary to achieve effective buffelgrass control.en_US
dc.typetexten
dc.typeElectronic Dissertationen
dc.subjectCenchrus ciliarisen_US
dc.subjectchemical controlen_US
dc.subjectinvasive plantsen_US
dc.subjectphenologyen_US
dc.subjectNatural Resourcesen_US
dc.subjectaerial herbicide applicationen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineNatural Resourcesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorSmith, Steven E.en_US
dc.contributor.committeememberSmith, Steven E.en_US
dc.contributor.committeememberKarpiscak, Martin M.en_US
dc.contributor.committeememberPapuga, Shirley A.en_US
dc.contributor.committeememberMcCloskey, William B.en_US
dc.contributor.committeememberRuyle, George B.en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.