40 



3. Spraying. In spraying the aim is to destroy the spore- 

 pustules on the wood by means of a caustic winter wash, but 

 the treatment is only in an experimental stage. The chief 

 difficulty is to wet the pustules thoroughly, as on account of 

 their powdery nature the spraying fluid runs off. This can 

 partly be overcome by the addition of soft soap. The mixture 

 which has proved most promising is as follows : 



1 lb. - caustic soda. 

 1 Ib. soft soap. 

 10 gal. water. 



The best time for applying a winter wash depends to some 

 extent upon the season. It should be applied as late as possible, 

 but not too late to run the risk of damaging the opening buds. 

 Generally speaking, the correct time is about the end of 

 February or the beginning of March, but in a cold, late season 

 the spraying may be delayed until the end of March. 



THE DIE-BACK DISEASE OF FRUIT TREES. 



(Cytospora leucostoma or other species.) 



Many varieties of fruit trees in almost every part of the 

 world are subject to a disease characterised chiefly by a dying- 

 back of the branches (see Fig. 1). This disease is caused by 

 a fungus named Cytospora. Plums, peaches, apricots, apples 

 and cherries (both wild and cultivated) have all been found 

 to be attacked by various species of this fungus. The dying- 

 back, which may extend to the large branches and even cause 

 the death of entire trees, is common to them all, but as the 

 symptoms vary somewhat, a brief description of the disease as 

 it occurs on the different kinds of trees is given below. 



Plums. Young, vigorous growing trees suffer more often 

 than older ones, the varieties " Victoria," " Czar," " Purple 

 Egg Plum " and " Prince of Wales " being frequently 

 attacked. The first sign of disease is a withering of the leaves, 

 often of a single branch. At the same time areas of bark which 

 may be on the main shoot or on a side branch, collapse and 

 turn brown, and the shoot or branch attacked commences to 

 die back. The dying-back does not as a rule confine itself to 

 the younger branches, but extends downwards and gradually 

 involves the largest branches and the trunk, and may then 

 endanger the life of the tree. 



After the branch or main stem has been dead some time, 

 the fungus produces Ifcs fructifications which can be recog- 

 nised externally as pimples or minute pustular swellings in 

 the bark (see Fig. 2). The fruit-bodies themselves, which 

 are found within these pustules, soon rupture the bark 

 horizontally and are seen on the surface as more or less 

 elliptical, flattened bodies, white in colour and perforated by 



