Date of Graduation

Fall 2019

Degree

Master of Science in Plant Science (Agriculture)

Department

College of Agriculture

Committee Chair

Chin-Feng Hwang

Abstract

Dicamba is a synthetic auxin herbicide which acts systematically and selectively controls broadleaf plants and has become increasingly popular in the past several years for weed control in commercial agriculture following widespread adoption of dicamba-resistant, transgenic soybean and cotton. Dicamba may be better acknowledged by growers of specialty crops, like grapes, for its capacity to drift miles away from the site of application and deposit on fields, remaining potent enough to cause crop damage and yield loss to vulnerable plants. Grapes are among the most susceptible agronomic crops to dicamba drift, showing visible injury at rates less than 1% of standard commercial applications. To counter the threat dicamba poses to the grape and wine industry, this study investigates the potential for the Vitis interspecific hybrid chambourcin to be utilized as a source of resistance to dicamba in future grape breeding efforts. Few reports on dicamba tolerance in grapes exist; however, previous field studies have implicated chambourcin as resistant. chambourcin and proposed susceptible cultivar Vitis vinifera cabernet sauvignon will be subject to sub-lethal, spray drift simulating treatments of dicamba as well as lab-based detached leaf assays that mimic the vapor drift of dicamba while simultaneously mitigating the effect of confounding environmental factors. Injury status will be determined in vivo by tracking shoot length to several weeks after treatment and by visual assessment of dicamba’s distinctive leaf cupping damage and stem and petiole distortion. In vitro, injury will be observed through leaf cupping and necrosis. The goal of these experiments is not only to determine the differential effects of dicamba drift on these two grapevine cultivars, but to produce valid and replicable experimental protocols by which to assess the severity of dicamba drift damage in any grapevine cultivar.

Keywords

dicamba, synthetic auxin, grapevine, herbicide drift, simulated drift, vapor drift, chambourcin, cabernet sauvignon, vitis vinifera, herbicide resistance

Subject Categories

Agricultural Science | Botany | Fruit Science | Weed Science

Copyright

© Bryce David Bentley

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