Video-The effects of spray drift on grapevine growth

2018 ASVO Seminar; Frontline pest and disease management for healthy vineyards
Symptoms and developmental implications of herbicide drift on grapevines

Dr Gerhard Rossouw, Commonwealth Scientific and Industrial Research Organisation (CSIRO)

Herbicide drift can have devastating consequences on grapevines and their developing crop. The source and type of herbicide causing the damage is, however, often difficult to identify, partially because the visual symptoms that develop after exposure to a specific herbicide have not yet been fully described in grapevines. The aims of this study were to (1) chronicle the symptoms of 2,4-D, Dicamba, MCPA and glyphosate drift on grapevines, (2) to investigate their impacts on leaf functioning, berry development and composition, and (3) to assess carry-over effects on vine productivity in the following season. Simulated herbicide drifts were applied to potted vines at the cessation of flowering and the progression of symptom development was monitored until fruit maturity. While the four herbicides induced similar visual symptoms, there were some unique features that could allow their differentiation. Dicamba exposure exhibited upward leaf rolling in conjunction with yellow and brown interveinal lesion development. Unlike MCPA, 2,4-D damage did not exhibit leaf margin necrosis, whereas severely deformed lateral shoot leaves developed only after 2,4-D exposure. Glyphosate related injuries emerged later than those induced by other herbicides. Photosynthesis of newly emerged mature leaves was impaired by prior 2,4-D, MCPA and glyphosate exposure. Fruit yield was significantly reduced by 2,4-D mainly as a result of bunch necrosis. This herbicide also increased juice titratable acidity but most of the other basic compositional parameters were not affected. While root structural development was limited by 2,4-D, Dicamba and MCPA, none of the herbicides altered root carbohydrate reserve levels. Primary bud necrosis was pronounced especially following 2,4-D and Dicamba exposure. Therefore, 2,4-D presents a significant hazard not only on the yield of the current season, but also for the next.