This section is from the book "The Gardener V2", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
We are not able to say what has caused your Grapes to shank. You give no data. The cause of shanking is a deficient supply of nutriment to the Grapes by the roots and foliage. The causes of this deficiency are various - the roots unhealthy, the foliage injured, and the crop too heavy. These evils present, and shanked berries are sure to prevail. You must judge whether any or all of these evils prevail with you, and remedy them as directed by us in the Practical Treatise on the Grape Fine, which is too long for quotation here.