Influence of Cover Crops on Canopy Density

Excessive canopy density can lead to fruit, leaf, and bud shading, which, in turn, can reduce fruit quality, increase disease intensity, and reduce fruitfulness in the current and subsequent year. Shaded fruit, relative to more fully exposed fruit, is often lower in anthocyanins, certain flavor and aroma compounds, sugar, and phenolics and may exhibit elevated titratable acidity and pH.¹
A range of vine and vineyard management tools is often used to compensate for excessive growth. Vine and canopy management options include:

• Shoot hedging
• Lateral shoot removal
• Leaf removal
• Modified training systems
• Use of size-limiting rootstocks

Vineyard management tools used to compensate for excessive growth include:

• Root pruning
• Aggressive use of cover crops
• Regulated deficit irrigation

Cover crops can be used to regulate vine vigor by providing an intentional competition with vines for water and other soil resources. A research paper written by Tremain A. Hatch, Cain C. Hickey, and Tony K. Wolf¹ compares the effectiveness of under trellis cover crops (UTCC) relative to conventional vineyard floor management with herbicides in controlling vine vigor.
The experiment consisted of root restricted versus non-root restricted vines on three different rootstocks, Riparia Gloire (Riparia) (Vitis riparia), 420A (V. berlandieri x V. riparia), and 101-14 (V. riparia x V. rupestris) undergoing either under trellis cover crops (UTCC) or herbicide treatments. The following graphical summary shows that regardless of root restriction or rootstock, the under trellis cover crops (UTCC) was much better at controlling canopy density when compared with herbicide treatment.

We will definitely be putting in a cover crop after we plant our vineyard to control canopy density and vine vigor which is one of the problems associated with eastern viticulture.
Reference:
1. Tremain A. Hatch, Cain C. Hickey, and Tony K. Wolf, Cover Crop, Rootstock, and Root Restriction Regulate Vegetative Growth of Cabernet Sauvignon in a Humid Environment, Am. J. Enol. Vitic., September 2011 62:298-311; doi:10.5344/ajev.2011.11001.