Excessively low vigour is generally attributed the following;

• Drought stress: use irrigation
• Low soil fertility: increase fertilisation, drainage, soil organic matter, etc...
• Disease: diagnose & treat

Excessively high vigour can be more difficult to control. Possible strategies include:

• Selection of low vigour rootstocks
• Water stress in irrigated vineyards
• Cover cropping in alleys
• High density planting: this only works in low potential sites
• Removing alternate vines along the row: this allows vines to spread along a greater length of trellis, thus reducing shoot vigour and canopy density
• Root pruning: a subsoiling tine is passed through the vineyard at 30 – 50 cm from the vine row after harvest or pre-budburst. Difficult to predict response as pruning will stimulate root growth.
• Retro-fitting a more complex trellis system: e.g., going from VSP to Scott Henry by increasing post length