Thesis
Glyphosate use in Washington State high-density apple orchards: glyphosate absorption, translocation, effects on tree growth, and effects on soil microbial composition
Washington State University
Master of Science (MS), Washington State University
05/2016
Handle:
https://hdl.handle.net/2376/101704
Abstract
Postemergence (POST) directed applications of glyphosate are often applied in Washington apple orchards for weed management, particularly to control deep-rooted perennial weeds and weeds that escape a residual herbicide application. Scientists, agriculture professionals, and growers have concerns that POST-directed applications of glyphosate may have negative effects on apple trees due to increased reports of herbicide injury in high-density apple plantings that suggest glyphosate injury. Therefore, studies were conducted at the Washington State University Sunrise research orchard and within two commercial orchards near Quincy, WA to determine the effects of glyphosate on tree growth in high-density plantings of two commonly grown eastern Washington apple varieties, and to determine if applications of glyphosate influenced shifts in soil microbial density and composition. Additional greenhouse and laboratory experiments were conducted on absorption and translocation of glyphosate following basal applications vs treatments to single leaves on a mid-tree branch. Effects of glyphosate applications in field were observed. Similar to previous research, effects of glyphosate applications were variable and it is difficult to determine a primary factor that leads to increasing or decreasing tree growth following applications of glyphosate. No differences in fungal or bacterial community density or composition were observed at the Sunrise research orchard site or at either site established near Quincy, WA. Analysis of 14C-glyphosate absorption applied to above graft basal (AGB) bark, below graft basal (BGB) bark, and to leaves (Foliar) on a mid-tree lateral branch indicate greater absorption when glyphosate is applied to basal bark compared to absorption by a foliar application. Observation of translocation from the AGB, BGB, and Foliar applications of 14C-glyphosate indicates that glyphosate translocates to the roots.
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Details
- Title
- Glyphosate use in Washington State high-density apple orchards
- Creators
- Alan James Raeder
- Contributors
- Ian Cristofer Burke (Chair)Mark Mazzola (Committee Member)Timothy W Miller (Committee Member) - Washington State University, Crop and Soil Sciences, Department of
- 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] :
- Number of pages
- 82
- Identifiers
- 99900525177501842
- Language
- English
- Resource Type
- Thesis