Practical Field Guide to Grapegrowing and Vine Physiology by Schuster Daniel & Paoletti Andrea & Bernini Laura

Author:Schuster, Daniel & Paoletti, Andrea & Bernini, Laura [Schuster, Daniel]
Language: eng
Format: azw3
Publisher: Board and Bench Publishing
Published: 2018-10-14T16:00:00+00:00

ILLUSTRATION 3.7 Spring frost damage.

ILLUSTRATION 3.8 Well-supported spring VSP canopy, Tuscany.

ILLUSTRATION 3.9 Spring canopy secured with wire clips, Tuscany.

Symptoms of ‘spring fever’ growth distortions, chlorosis and marginal burn of leaves can appear in seasons of cold spring nights alternating with hot days, causing a physiological response in vines that find it difficult to take up and trans-locate nutrients within the rapidly expanding canopy of leaves.

Applications of seaweed preparations and foliar sprays of a complete, balanced nutrient mix, helps to moderate the most severe symptoms of this disorder, with normal growth rates and vine health returning with more settled and warmer weather. It will be noted that some varieties are more sensitive to ‘spring fever’ than others. Cabernet, Sangiovese or Petit verdot are, for example, more sensitive than Riesling or Chardonnay. On reaching optimal height and canopy size in late spring, balanced vines will reach trimming height some 10–12 weeks after budburst. The timing of trimming should ideally be at flowering or early fruit set, to cause a temporary flow of carbohydrates downward toward the fruit clusters.

Removal of lower sub-laterals, which compete for water and nutrients with nearby clusters, is done at this time for the same reason. From this point onward, the grower will aim to maintain the size and canopy density more or less constant, to create the optimal conditions for the growth, ventilation and maturation of the grapes without undue competition from vegetative growth. Trimming of the top and sides of the canopy is repeated as required during the post-flowering, berry growth period, whilst canopy environment is kept open at 1–2 leaf depth to maximise the effects of sunlight and disease control.

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