Thesis
Herbicide effects on growth and seed germinability of broadleaf dock (Rumex obtusifolius)
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/103132
Abstract
Knowing which herbicides to use against a weed species coupled with a knowledge of when the seeds are most likely to germinate allows growers to devise successful management programs. To obtain these values for broadleaf dock (Rumex obtusifolius L.) growing under Pacific Northwestern (PNW) environmental conditions, two field herbicide trials were established in a highly infested fallow field near Mount Vernon, Washington, USA, and a subsequent seed germination test was conducted. In the first trial, 16 herbicides registered in blueberry (Vaccinium corymbosum L.) were applied May 23, 2016 to bolting broadleaf dock and, in a second trial, 18 herbicides were applied October 28, 2016 to broadleaf dock regrowth approximately one mo after mowing. Seed from broadleaf dock plants surviving spring herbicide application were collected to assess the herbicidal impact to germination. In both herbicide trials, glyphosate at 3.86 kg ae ha-1 provided the greatest broadleaf dock control (94% at 8 wk after spring treatment and 20% at 3 wk after fall treatment). Also in the spring trial, terbacil (2.69 kg ai ha-1), diuron (2.69 kg ai ha-1), and dichlobenil (4.39 kg ai ha-1) gave 85%, 68%, and 65% control at 8 wk after treatment, respectively. Fall-applied pronamide (2.24 kg ai ha-1) and dichlobenil (4.39 kg ai ha-1) provided >85% control on April 21, 2017. Among spring-applied herbicides, only clopyralid (0.14 kg ae ha-1) reduced seed germination compared to seed gathered from nontreated plants (27%), indicating that this herbicide applied to bolting broadleaf dock may slow the spread of this weed in PNW berry fields. Further, because broadleaf dock seed was shown to optimally germinate at 20oC, it appears that preemergence herbicide treatments should be applied prior to the beginning of summer in the PNW to optimize control of germinating broadleaf dock seeds.
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Details
- Title
- Herbicide effects on growth and seed germinability of broadleaf dock (Rumex obtusifolius)
- Creators
- Wiharti Oktaria Purba
- Contributors
- Timothy W. Miller (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525168101842
- Language
- English
- Resource Type
- Thesis