RESISTANT VINEYARDS GRAFTING, PLANTING, CULTIVATION. 117 



All the vital processes progress more rapidly when the cuttings are 

 kept warm. To delay them, therefore, we keep the sand cool, and to 

 hasten them we make it warm. In the beginning of the season and 

 up to the middle of March we keep the sand cool. This is done by 

 keeping the bed covered during the day when the sun is shining, and 

 uncovering occasionally at night when there is no fear of rain. If the 

 black-and-white wagon-cover is used the white side should be placed 

 outward to reflect the heat. The temperature should be kept about 

 60 F. or lower. 



About the middle of March the temperature of the bed should be 

 raised. This is done by removing the cover during warm days and 

 carefully covering at night. If necessary the layer of moss or straw 

 should be removed on sunny days and then replaced. The temperature 



68 F. 77 F. 86 F. 



FIG. 16. Callus formed at various temperatures in eight days. 



of the sand at the level of the unions should be about 75 F. during 

 this period. If the temperature rises higher than this there will be a 

 more abundant production of callus, but it will be soft, easily injured, 

 and liable to decay. 



At the end of four weeks after warming the bed, the union should be 

 well cemented. The callus should not only have formed copiously 

 around the whole circumference of the wound, but it should have 

 acquired a certain amount of toughness due to the formation of fibrous 

 tissue. It should require a pull of several pounds to break the callus 

 and separate stock and scion. When the callus has acquired this quality 

 the grafts are in condition to be planted in the nursery, and may be 

 handled without danger. If taken from the bed while the callus is 

 still soft, many unions will be injured and the grafts will fail, or unite 

 only on one side. 



If left as long as this in the callus ing bed most of the scion buds 

 will have started and formed white shoots. These shoots, however, 



3 BUL. 180. 



