252 



The Canadian Horticulturist. 



THE PEACH LEAF CURL. 



HIS peculiar disease is widespread both in this countty and in 

 Europe, occurring wherever the peach is grown. It often severely 

 injures nursery stock ; young, thrifty-growing trees are more sub- 

 ject to its attacks than those more mature. The curl is limited to 

 the period when the young shoots and leaves are most tender ; 

 after the tissues of these parts are fully formed or matured they are 

 no longer affected. The disease shows itself as'soon as the leaves 

 are expanded. By the first or middle of June the only signs of the malady are 

 the withered leaves on the ground and the shriveled shoots on the tree ; new 

 leaves have already developed on the lateral twigs. The illustration. Fig. 797, 

 shows the characteristic appearance of a peach leaf affected with the curl, and the 

 same engraving illustrates a twig diseased from the same cause. Frequently the 

 entire leaf is involved, the diseased part being somewhat thicker and of a more 

 fleshy texture than that in health. The under surface is usually smooth, but the 

 upper has a more or less mealy appearance. When the leaf stock is affected it 

 swells to several times its normal thickness and seldom attains its full length. 

 These portions have a pale green color, the surface is swollen and uneven, and 

 turns black and dies. The cause of peach-leaf curl is a minute fungus called 

 Taphrina deformans. It is closely related to the fungus which causes " plum 

 pockets." The mvcelium or spore-producing part of this fungus forms a net- 

 work of threads resembling a string of beads m 

 the tissues of the peach leaf. This is illus- 

 trated in Fig. 798. From these threads the 

 spores or seeds are produced by which the 

 disease is spread from tree to tree. These 

 falling on young tender shoots penetrate their 

 substance and cause them to curl up and 

 finally die. So little is really known of the 

 life history of the curl that little can be said 

 regarding preventive measures. Removing 

 and destroying all the leaves and young shoots 



Fig. 797. — Leaf CURL, affected leaf 



AND TWIG. 



Fig. 798.- 



-Leaf curl F1LAME?'T.S 

 magnified. 



