Chlorosis | A disorder from which vines and other (crop) plants may suffer, especially when grown on limestone. Chlorosis is the manifestation of a mineral deficiency, which yellows part or all of the vines foliage due to a lack of chlorophyll.
Cause | ‘High free lime content in soil restricts access to iron and, to a slightly lesser degree, manganese. This interferes with the synthesis of chlorophyll, an essential green colouring matter in the leaves which uses sunlight to convert simple elements into plant food, causing chlorosis, which is the yellowing of the plant’s leaves. This is normally countered by the selection of highly [resistant] rootstock varieties,’ says Tom Stevenson (1988, p54).
See also | Urticae 500.
Tom Stevenson, Champagne (Sotheby’s, 1986; second updated impression 1988).