ACCIDENTS, DISEASES, PARASITES. 155 



CHAPTER X. 

 ACCIDENTS, DISEASES, PARASITES. 



IST. ACCIDENTS DUE TO UNFAVORABLE CONDITIONS. 

 Although vines are generally favoured in the regions 

 where they are cultivated with all the conditions required for 

 the normal development of the different phases of their 

 vegetation, it sometimes happens that modifications in the 

 meteorological circumstances injure the growth of the crop. 

 We will now study these different accidents, their effects, and 

 the means of avoiding them. 



(A.) FROSTS. 



Vines may be affected by frost in autumn, winter, and 

 spring ; but its action differs in each season and does not 

 have the same effects on account of differences of the 

 state of vegetation and in the intensity of the frost. 



(a) Autumn frosts. These are rarely to be feared in 

 regions where the vine is cultivated. However, they occur 

 sometimes in low-lying lands when heavy rains are followed 

 by north winds. According to Petit-Lafitte this occurs every 

 fourteen years in the Gironde.* 



Their general effect is to suddenly and prematurely check 

 vegetation and injure the ripening of the canes, which 

 generally dry. If the crop is still on the vine it may 

 suffer seriously, the berries being injured by the action of 

 cold, and always resulting in considerable loss. In countries 

 liable to autumn frosts one may remedy this accident by 

 planting cepages ripening early. 



(b) Winter frosts. The stoppage of the vegetation in 

 winter enables the vine to withstand low temperatures 

 without being injured. However, when the cold reaches ' 

 10 to 15C. some stumps may die altogether, others are cut 

 down to the level of the soil or lose some of their arms or 

 spurs ; at other times with less low temperatures 8C., but 

 in damp low-lying lands the buds alone are killed, and 

 shoots, generally sterile, grow on the old wood near the 

 surface. This is commonly termed " return of sap." 



* La Vigne dans le Bordelais, by Petit-Lafitte, Paris, Rothschild, 1868, page 460. 



