THE PLUM ] 47 



should commence along with the first appearance of new 

 foliage, and continued at intervals of ten to fifteen days 

 until the first rains of autumn. In the second year some 

 watering may be done, especially in late spring and early 

 summer to keep the vigour of the young trees and pro- 

 mote their growth. However, in good soils with a fairly 

 moist subsoil, plum trees which have become well esta- 

 blished, will derive little benefit from irrigation. In fact 

 it is not possible to grow summer vegetables in the plum 

 orchard, because the frequent watering which is neces- 

 sary for the vegetables, besides impairing the quality of 

 the fruit will cause the plum trees to gum freely and to 

 die off after a short term of sickly existence. 



Gumming of a dangerous character is also too 

 frequently the result of the excessive use of stable manure 

 and of other badly fermented organic fertilizers. Manures 

 too rich in nitrogen behave in the same manner, and 

 therefore the complaint cannot be ascribed solely to the 

 fermentable material. It is not to be supposed that the 

 plum tree is not in need of fertilizers, but these should 

 be used with caution. It is a good plan to apply stable 

 manure as a top dressing in autumn when the soil is 

 tilled for the first time after the rains, and in the autumn 

 of the following year the soil is trenched superficially to 

 a depth of 10 to 15 c.m. thus bringing the fertilised 

 upper layer of the soil in contact with the roots. On light 

 porous soils which are frequently poor in potash, a 

 dressing of wood ashes, along with some superphosphates 

 may be applied in autumn just before trenching, and 

 this treatment of the soil along with the operation of 

 trenching should be done every fourth year. Green- 

 manuring necessarily imparts to the soil much ferment- 

 able material and on that account is not very recom- 

 mendable for the plum tree. The best It guminose plant 

 for this purpose is the bitter vetch (Vicia or Ervum Ervi- 

 lifi) as it decays quickly when interred. The bitter vetch 

 may he sown broadcast in December or January, at the 



