Leaf variegations of perennial delphiniums

Abstract

does not appear. First page follows. Leaf variegations and variegations in flowers are not uncommon among ornamental flowering plants. In perennial delphiniums two types of leaf variegations, for which the names “golden-leaf” and “silver-leaf” variegations are proposed, have been observed in seedbeds, in cold frames covered with muslin, in commercial fields of delphiniums grown for seed production and for the cut-flower trade, in nurseries, and in home gardens. Reichert (14)3 lists among diseases of ornamental plants in Palestine a nonparasitic yellow-leaf discoloration of Delphinium sp. A leaf variegation somewhat similar to the leaf variegations of delphinium has become serious in certain strawberry varieties, affecting 25 to 50 per cent or all of the plants. The disease has been called “strawberry mosaic” (1), “suspected strawberry mosaic” (2), (8), “noninfectious chlorosis” (4), “June yellows” (11), “yellows” (9), (10), and “gold leaf” (8); and at present the accepted name is “leaf variegation” (3), (5), (6), (7), (12). Berkeley (1), Guba (8), Plakidas (11), and Demaree and Darrow (7) failed to transmit leaf variegation in strawberries by insects, sap inoculations, and grafting of diseased and healthy runners, and thus presented conclusive evidence that the disease is noninfectious and not caused by a virus. Berkeley (2) was first to suggest that leaf variegation in strawberries was of genetic origin. Clark (4) expressed the opinion that the disease was caused by a gene mutation and was hereditary. The evidence as a result of breeding work, according to Demaree and Darrow (7), suggests a. sporting or mutation, which has been considered in most instances as the appearance of a recessive character in somatic tissue; they state: “Evidence so far indicates that leaf variegation is not due to a single gene. Even if by selfing no yellow plants appear, this is by no means evidence that a complimentary gene for yellowing may not be in the variety.”