DISEASES OF PLANTS. 733 



''Some cln.stt'is upon a vino sccmii to be more free from shelling than others upon 

 tlie siiuio pliiut. This seems to be duo in many cases to its location npon the caue, 

 but there are so many exceptions tliat no definite rule can be laid down. In general, 

 however, it may be said that of the clusters found upon a certain cane the one whicli 

 is situated farthest from the main stem of the plant is most seriously affected. . . . 



"Another peculiarity which may sometimes be seen, although cases of it are very 

 rare, is the shelling of bei-ries upon only one portion of the vine, as, for instance, 

 those borne upon the canes which spring from an arm, the difficulty thus affecting 

 only one half of the plant. . 



"It very commonly occurs that plants in certain jjortious of a vineyard shell, while 

 the large majority of them do not. The lino is sometimes so sharply drawn that the 

 aff'ected plant may be entirely surrounded by healthy vines; and it is uot uncommon 

 to find a healthy vine in the midst of those which shell. Occasionally the plants in 

 a row are quite different as regards the amount of fruit which is lost, some retaining 

 all, while others lose fully 75 per cent. Such vineyards, however, do not represent 

 the large majority. In these, the shelling is more or less uniform throughout the 

 vineyard, and only in exceptional cases does the loss reach 50 per cent of the crop. 

 The total loss will probably not exceed 5 jier cent of the entire yield this year. 



"The taste of shelled grapes differs decidedly from that of those remaining upon 

 the upper portion of affected clusters, and still more from that of berries which are 

 borne upon vines iu which no shelling takes place. This difference is very notice- 

 able in Concords. Grai)es of this variety, when grown under favorable conditions, 

 are sweet and very agreeal)le to the taste, on account of a llavor which is peculiar 

 to the variety. Shelled grapes are extremely insipid, and are unpalatable, not only 

 from a want of taste but also from a certain disagreeable flavor which, though sel- 

 dom strong, is still perceptible. Berries which remain npon shelly vines lack flavor, 

 but otherwise they do uot appear to possess any particularly disagreeable qualities." 



Vines wbicb have shelly grapes are said to be nearly always affected 

 by diseased foliage. This condition usually appearing iu July or 

 August, causes the death of the leaf tissues. The leaves on the extrem- 

 ities of the shoots show a yello\v coloration more or less following their 

 periphery. Soon the yellow portion turns brown, causing the leaf to 

 curl. In severe cases the brown foliage becomes conspicuous. Tiie 

 shelling is not always accompanied by a decided discoloration, but the 

 two are usually associated. A dark discoloration is often found between 

 the i^rincipal veins and is attributed to the same cause as that causing 

 the death of the edges. In some of its aspects this disease resembles 

 apoplexy and rougeot, common in parts of Europe, but the author 

 doubts their identity. In 1890 D. Cr. I'airchild, of the Division of 

 Vegetable Pathology of this Department, investigated and reported 

 on' a dise&.se of grapes i^robably the same as here described. 



The ascribed causes of the shelling are grouped by the author under 

 4 heads — (1) injuries due to parasites, (2) improper conditions of the vine, 

 (3) conditions of the soil, and (4) conditions of the atmosphere. In con- 

 sidering the various causes the author thinks that insects do not cause 

 the disease, but that fungi may aggravate it, and that the dying of the 

 leaves is a manifestation of the disease. The conditions of the vine, 

 causing the stems to shrivel and the fruit to ripen prematurely probably 

 cause this trouble. Premature ripening of the wood and overbearing 



» Jour. Mycol., vol. 6, p. 96 (E. S. E., 2, p. 455). 



