GRAPE DISEASES 263 



may be noted : certain fungi, insects, lack of phosphoric-acid 

 and meteorological conditions. Those agencies which are 

 thought to increase or favor shelling are : a weakening of the 

 vines due to overbearing, heavy vegetative growth, excessive 

 nitrogen supply emphasized by over-tillage, prolonged drought 

 or excessive rains followed by drought, and a poorly developed 

 root-system. One authority concludes that a lack of potash 

 is in many cases the primary cause. There is considerable 

 evidence, however, that this is not a factor. The agencies 

 already listed as favoring the trouble may be regarded as 

 exciting causes. 



Control. 



Since the main cause of shelling is apparently deficient 

 nourishment, steps should be taken to correct such conditions. 

 The soil should receive attention; potash should be applied 

 where needed. Cultivation of poorly-nourished vines aggra- 

 vates shelling ; proper cultivation is essential. Care should be 

 taken to properly handle vines that overbear; such plants 

 need an adequate food-supply. In France it has been advised 

 that shoots be pinched or cut off after the development of six 

 to eight leaves where the grapes are borne ; or twelve to fifteen 

 on those shoots not carrying fruit. This diverts the elaborated 

 food from the shoots to the berries. This procedure is said 

 to give satisfactory results in France. 



REFERENCES 



Sturgis, W. C. Notes on the so-called "shelling" of grapes. Con- 

 necticut Agr. Exp. Sta. Kept. 1896 : 278-281. 1897. 



Rainsford, E. H. Coulure, or non-setting of grapes. Queensland Agr. 

 Jour. 10:41-42. 1902. 



Clinton, G. P. Report of the botanist for 1906. I. Notes on fungous 

 diseases, etc., for 1906. Grape, Vitis sps. Shelling and rot. Con- 

 necticut Agr. Exp. Sta. Rept. 1906 : 315-316. 1907. 



Lodeman, E. G. Some grape troubles of western New York. Shelling 

 or rattling. Cornell Univ. Agr. Exp. Sta. Bui. 76:413-440. 

 1894. 



