GRAPE VINES COLOURING GRAPES. 307 



moist, and is followed by a period of cold and dry weather check to growth, 

 contraction of the skin rust. Prevention of rust must be sought in careful 

 management. 



Warts on Vine Leaves. This affection seriously cripples the leaves and hinders the 

 due performance of their functions. It is caused by a sudden exposure of the young 

 growths to cold and dry air after they have been made in a close and warm atmosphere 

 excessively charged with moisture. Small green excrescences form on the under side 

 of the leaves, and the upper surface is furrowed and uneven. It is not an indication of 

 ill health, but of irrational treatment. Therefore, avoid late and imperfect ventilation 

 on bright mornings, admit air carefully on the return of bright weather after dull periods, 

 and when the external air is sharp, do not allow it to drive full upon the foliage nor 

 produce cold dry currents. 



Colouring Grapes. This commences with the last swelling. Air without a cold 

 draught is the chief essential. Sufficient healthy foliage, fully exposed to light and air, 

 is also an important factor in the colouring of grapes. Upon the amount of chlorophyll, 

 formed by the foliage from the unfolding of the buds to the berries showing colour, 

 depends the dense black of dark or the rich amber of light grapes. It is too late 

 to seek colour when the grapes are ripening on vines that have had the foliage 

 crowded, or when it is thin by too rapid forcing, insufficiency of nourishment, or 

 exhausted by red spider, or when the vines are overcropped. Hamburghs require 

 about six weeks to ripen thoroughly when colouring has commenced ; Muscats take 

 nine weeks to finish. Thick-skinned grapes continue swelling after the colouring 

 appears perfect, and require three months from the first tinge of colour to complete the 

 ripening process. 



It is an imperative necessity to retain the earliest developed foliage on Muscats as 

 long as possible consistent with the ripening of the wood. The best way to effect this 

 is by maintaining a genial atmosphere, and say a minimum temperature of 65, with 

 the usual rise by day, the damping and watering to be done in the same way as 

 during the earlier part of the season. Suppose the grapes commence colouring at the 

 end of July, this treatment should be continued till October, when a little less heat, 

 say 60 as the minimum, will suffice. Early in November the temperature should be 

 55 at night, and so continue until the leaves fall. This, in the case of Muscat of 

 Alexandria started in March, occurs about the middle of December. We allude in a 

 special manner to the autumn treatment of this most valuable grape, because when 



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