Thesis
Chemical control of rush skeletonweed (Chondrilla juncea L.) during summer fallow in eastern Washington
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000004085
Handle:
https://hdl.handle.net/2376/125049
Abstract
Rush skeletonweed (Chondrilla juncea L.) is a problematic weed for growers in the wheat-fallow regions of eastern Washington. Dense infestations result in major yield loss due to competition and inadequate soil moisture for wheat germination. Chondrilla juncea flourishes during the fallow year in the absence of crop competition. Summer fallow is a critical time to control C. juncea prior to planting winter wheat. Previous research on chemical control of C. juncea shows the effectiveness of synthetic auxin and sulfonylurea herbicides. However, these products are expensive when applied at rates adequate for control of C. juncea in fallow, or leave chemical residue in the soil that can have damaging effects on a future crop. A weed-sensing sprayer was used to evaluate the role of increased spot-spraying rates for control of a perennial weed, and an economic analysis was done to compare application cost through the weed-sensing sprayer to a broadcast sprayer. Several different synthetic auxin herbicides and a sulfonylurea were applied to C. juncea on fallow ground. When populations of C. juncea were sparse, the weed-sensing sprayer allowed for good control while simultaneously reducing the cost of application in comparison to broadcast spray application. Dense populations resulted in economic loss due to increased rates used through the weed-sensing sprayer. A separate greenhouse study related to fallow management of C. juncea was conducted in order to evaluate the interaction in tank-mixtures of aminopyralid or clopyralid with glyphosate. Results of the study conclude that additive or synergistic interactions occur between aminopyralid or clopyralid and glyphosate when applied to C. juncea. Growers interested in using glyphosate for the control of other weeds in summer fallow can tank mix glyphosate with aminopyralid or clopyralid without fearing a loss of efficacy on C. juncea.
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Details
- Title
- Chemical control of rush skeletonweed (Chondrilla juncea L.) during summer fallow in eastern Washington
- Creators
- Jacob W. Fischer
- Contributors
- Drew Lyon (Advisor) - Washington State University, Department of Crop and Soil Sciences
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Crop and Soil Sciences
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900890788101842
- Language
- English
- Resource Type
- Thesis