The spraying of herbicides to keep the undervine area free from competing vegetation is a common practice in vineyards. However, as concerns about negative effects of herbicides rise and with increasing numbers of growers wanting to grow grapes in a sustainable manner, alternative methods to herbicides must be investigated. A three-year trial on the effects of various forms of vegetation management in the undervine area of vineyards in New Zealand was therefore undertaken. Herbicide spray was compared with undervine cultivation or mowing. The trial was carried out in Pinot noir and Sauvignon blanc vineyards in the Marlborough region and in Merlot and Syrah vineyards in the Hawke’s Bay region. Trials were set up as randomized block designs with six replications of each treatment in each variety. Vines with undervine mowing showed reduced vegetative growth in the first year, but devigoration only became evident in the cultivation treatment in the third year of the trial. The change in vine trunk circumference over the course of the trial showed the largest gain from the herbicide treatment and the smallest gain from the mowing treatment except in Sauvignon banc. Harvest yield was generally lower in the mowing treatment, at least partly explained by reduced berry size. Mowing significantly and consistently reduced YAN compared with herbicide in all varieties, but there were few other differences in must basic composition. There was a consistent reduction in IBMP in Sauvignon blanc fruit and wine due to mowing. The treatments also significantly affected the species of plants found in the undervine area at the end of the study. This shows that choice of undervine weed management strategy has significant effects on vine growth and productivity, potential wine quality, and the ecology of the vineyard as a whole.

Funding Support: New Zealand Winegrowers, MAF Sustainabe Farming fund, EIT