io6 THE FRUIT GROWER'S GUIDE. 



especially where the borders are cropped, heavily manured, and the roots wounded in 

 digging. 



3. Fungus on the Roots. This is generally the result of using manure or leaf 

 mould that frequently contains woody matter, the mycelium of the fungus being 

 introduced with those substances, and spreading to the roots of peach or nectarine 

 trees, weakening or killing them. Drought at the roots also favours the development 

 of the destructive mycelium, and should be guarded against. Flooding the border with 

 lime water sometimes proves effectual, but in bad cases it is necessary to remove the 

 trees and soil. 



4. Sunburn. Trees against walls and on roof trellises sometimes have the branches 

 and trunks so dried by the sun as to become enfeebled and prevent the flow of the sap, 

 the branches dying or falling a prey to "borers." The prevention of sunburn is 

 important. It is best secured by keeping the trees so furnished with young wood and 

 leaves as to shade the branches, young shoots being trained over naked limbs for that 

 purpose. Strips of straw mat also shield the main branches. 



DISEASES. 



Blister. This is caused by a fungus (Exoascus deformans, Fig. 30), and is chiefly 

 confined to the leaves, but it also attacks young shoots and causes their malformation. 

 The affected parts become swollen and distorted, and the leaf or shoot twists and curls 

 into peculiar forms. A pale bloom appears on the attacked leaf, best seen on the under 

 surface, and this under the microscope is found to consist of innumerable erect, slender 

 cells containing eight spores each ; these issue from the mycelium that derives its support 

 from the tissue of the leaf, and destroys its functions. Ultimately the leaves affected 

 with the fungus wither and fall prematurely. Blistered leaves and shoots are common 

 on wall trees in cold springs, especially after frosts and cutting winds, and protection by 

 some of the means described on page 81 is very desirable. Spraying the trees with 

 precipitated carbonate of copper in suspension (Vol. I., page 241) once before the buds 

 unfold, again when the fruit is set, and a third time three weeks afterwards, is also 

 recommended for preventing attacks of the disease and hindering its spread. The 

 remedy is to cut off and destroy the affected shoots and leaves, but this must be done 

 gradually, removing some of the worst first, and so on at intervals of a few days until 

 the whole are removed and burned ; then, with genial weather, the trees will make clean, 

 healthy growth. 



