Understanding and mitigating the impact of off-target herbicide drift

Research output: Contribution to specialist publicationArticle

Abstract

Herbicides are widely used to control weeds in broadacre crop fields, often during springtime. Grapevines, however, are sensitive to the phytotoxic effects of many herbicides, especially during the stage of early shoot growth and around flowering. Climatic conditions, including prevailing winds, low relative humidity and high atmospheric temperatures can all increase the risk for off-target spray vapour drift, potentially moving for several kilometres (Felsot et al. 2010). Phenoxyacetic acid type herbicides, including 2,4-D, are particularly renowned for causing drift incidents, and may impair fruit yield and canopy growth in exposed vineyards (Ogg et al. 1991, Al-Khatib et al. 1993). Other herbicides, including glyphosate, are sometimes used in vineyards to control weeds between vines and may therefore be absorbed through grapevine leaves and roots.

A simulated herbicide drift study was conducted at the National Wine and Grape Industry Centre in Wagga Wagga during the 2017/18 growing season. The study formed part of Wine Australia’s Incubator Initiative with the NSW Wine Industry Association as regional partners. Four commonly used herbicides (2,4-D, Dicamba, MCPA and glyphosate) were applied to five-year-old potted Tempranillo grapevines at the cessation of flowering to simulate drifts of approximately 10% relative to the label rates. The hormonal-type herbicides, 2,4-D, Dicamba and MCPA, mimic the action of the natural plant hormone auxin in plants, and ultimately cause uncontrolled cell division and high ethylene production in affected tissues (Cobb and Raede 2010). Glyphosate, on the other hand, works by inhibiting the biosynthesis of aromatic amino acids (phenylalanine, tryptophan and tyrosine) in the target plant, subsequently affecting many aspects of plant metabolism including the production of phenolic compounds (Cobb and Raede 2010). The main aim of this study was to better understand the repercussions of the four herbicides on vegetative and reproductive grapevine development until fruit maturity. The visual foliar, shoot and fruit injuries caused by the different herbicides were additionally documented. Photographs and a detailed description of these injuries are available in the 2018/19 NSW DPI Grapevine Management Guide.
Original languageEnglish
Specialist publicationAustralian Society for Viticulture and Oenology (ASVO)
Publication statusPublished - 2018

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