THE TREATMENT OF THE SHOOT . 167 



resorted to for the purpose of stimulating the scion itself to 

 the formation of roots. In this case the numerous incisions 

 are made in the bark of the scion alone at its lowest end, and 

 the incisions are covered up tightly with stimulating soil. 

 Roots should then soon make their appearance,' and thus the 

 independent nutrition of the scion would be commenced. 

 This procedure would be applicable in the case of dwarf trees, 

 such as pears grafted on quince stock, and apples on Doucin 

 or Paradise stock. 



The slitting of the bark should be carried out soon before 

 the unfolding of the leaves, as the pressure of the bark is 

 greatest at this period, and the releasing of this pressure 

 will have the greatest effect upon the growth of the cambial 

 zone. 



If, however, the bark is slit in order to get rid of an ex- 

 cessive supply of water and nutritive material, then no special 

 time can be recommended for the operation. It may be 

 resorted to if at, or shortly after, the commencement of the 

 vegetative period, a number of organs which would naturally 

 have used up the nutritive material have been removed. A 

 very well known instance is the disease of the gooseberry, 

 which we have discussed in a preceding paragraph. The 

 swellings on the stem of the wild stock below the point of 

 insertion of the scion are formed because the water which the 

 roots of the stock have been forcing into the stem during the 

 winter is not sufficiently used up. For it is, unfortunately, 

 often usual to cut away the lateral shoots too soon ; con- 

 sequently the bark is over-loaded with water, and the cells 

 elongate in the region where they are youngest and where the 

 pressure of sap is greatest, i.e., at the uppermost portion of the 

 wild stock. Thus a spongy swelling is formed, which bursts 

 and then dries up, causing also the drying up of the graft. 

 This unhealthy condition may be avoided by getting rid of 

 the superfluous water and of the plastic material which was 

 intended for the lateral shoots ; both these results can be 

 attained by slitting the bark. 



Similar diseased conditions make their appearance, especially 

 in cherries and peaches, if too many superfluous eyes are 

 removed, or too many young shoots have their tips removed. 



