56 



" Curl " of Peach Leaves. 



has been widespread and severe, and flowering peaches in 

 shrubberies planted for ornamentation have suffered seriously ♦ 

 The leaves of infected trees dry up and ultimately fall. If fruit 

 is formed, it soon drops when the leaves are much affected, and 

 the whole tree is rendered unhealthy and barren. It has 

 been erroneously thought that this disorder is occasioned 

 by aphides. Aphides are frequently found in the folds 

 of the infected leaves, as they very often infest leaves of 

 many plants and trees that are unhealthy, but on the same 

 tree curled leaves may constantly be seen which have no 

 trace of aphides upon them. 



In the first stage of this attack the green skin, or 

 epidermis of the leaf, becomes much thickened and assumes 

 a velvety appearance. The leaf becomes more and more 

 curled and contorted, and is finally of a light red colour, 

 generally upon the edges of the folds or " curls." 



If a very thin section is taken from a part of the " curl " 

 and placed under the microscope, the mycelium of the fungus 

 may be seen upon the walls of the leaf tissues. The 

 mycelium has many branches, or ramifications, which finally 

 assume the form of rounded cellules, from which asci are 

 formed containing the spores of the fungus. There are from 

 six to eight spores in each ascus. The spores are nearly 

 globular and colourless. Prillieux says that the spore is 

 able to emit a tube of germination which in favourable 

 circumstances is able to penetrate the cells of the epidermis 

 of the leaf. The fungus is also found on the young shoots 

 of peach trees, and causes a thickening of the part affected. 

 In this way the fungus is, undoubtedly, preserved during the 

 winter, and the spores coming from the shoots in the early 

 spring infest the leaves near them. The spores are borne 

 by the wind from leaf to leaf, and, unless the progress of the 

 fungus is arrested, in the course of two or three years the 

 whole of the peach trees in a garden may become infested. 

 Some trees were noticed last year having several "curled" 

 leaves upon them, and this year these trees are very badly 

 diseased, having 50 per cent, of their leaves distorted. The 

 long-continued cold winds in the latter part of April and 



