Complete vineyard floor cover crops favorably limit grapevine vegetative growth

- Five, complete vineyard floor cover crops were evaluated in a humid climate.
- Elite II and KY-31 tall fescues were the most persistent and effective cover crops in regulating vine vigor and size.
- Complete vineyard floor cover crops improved grapevine canopy architecture.
- Vine water potential and estimated soil water use were minimally affected by cover crops.
- Grape crop yield was minimally affected by cover crops over six years of study.

Complete vineyard floor cover crops were evaluated in a long-term study for their ability to regulate excessive vegetative growth of the grapevine (Vitis vinifera L.) variety 'Cabernet Sauvignon'. Treatments were: tall fescue (Festuca arundinacea Shreb.) 'KY-31′ and 'Elite II', hard fescue (Festuca ovina L.) 'Aurora Gold', perennial ryegrass (Lolium perenne L.), orchardgrass (Dactylis glomerata L.), and an under-trellis herbicide strip combined with KY-31 fescue interrows. Compared to herbicide-treated soil strip, Elite II fescue reduced vine pruning weights (kg/vine) 28%, individual cane weight (g) 20%, and canopy leaf layer number 25%. KY-31 fescue produced the greatest biomass and stand density, while perennial ryegrass produced the least biomass and Aurora Gold hard fescue produced the lowest stand density. Elite II fescue produced less biomass but equivalent stand density compared to KY-31 fescue. Treatments minimally impacted vine water potential (Ψmd, Ψstem), indicating that the grasses were not overly competitive with grapevines for soil moisture. All grass treatments tended to depress grapevine nitrogen levels relative to the under-trellis herbicide strip treatment, but no treatment resulted in vine nitrogen levels below the acceptable sufficiency range. Because of its establishment and growth characteristics, desired suppression of vine vegetative growth, and its low impact on crop yield, we considered Elite II fescue the optimal cover crop evaluated.