THE PEACH AND THE NECTARINE ] 335 



margin. In upper Italy Cercosporella persica Sacc. forms 

 whitish spots on the upper surface of the leaf; and 

 Clasterospomum Amygdalearum Sacc. which is also un- 

 known here but is frequent all over the continent, causes 

 the formation of dry circular or roundish brown yellow 

 blotches, surrounded by a dark red or blackish margin. 

 Corineum Beyerinckii Oud. is another fungus rather 

 frequent in Italy which forms small irregular red patches 

 or blotches which afterwards turn brown, on the under 

 surface of the leaf. 



The rust of the plum, Puccinia Pruni-spinosae Pers. is 

 occasionally seen on the leaves of the peach in autumn, 

 but a much more frequent parasite is Sp hae roth tea pannom 

 Lev. which is the cause of the mildew of the peach as well 

 as of the rose. This mildew develops as a mealy powder 

 on the growing twigs of the peach in summer, and is 

 more frequent on young trees, and on trees growing on 

 irrigated lands. The mildew of the peach may be kept 

 in check by dusting with powdered sulphur containing 

 3 to 5 p. cent, of sulphate of copper, or by spraying with 

 a solution of sulphide of potash or with sulphur-lime 

 mixture. 



Exoascus deformans Fckl. is the cause of the well 

 known peach leaf-curl. The disease may develop early 

 in spring along with the new foliage, but is more frequent 

 about midsummer following in the wake of an attack of 

 Aphis. As a result of this infection the foliage becomes 

 blistered, wrinkled and curled, and the growing twigs 

 become swollen and contorted, with the formation of an 

 excessive number of slender lateral twigs, which usually 

 die off in winter. The disease also sometimes attacks 

 the fruit in Italy, where it is frequent enough on the fruit 

 of the plum, but in these Islands neither the peach nor 

 the plum is ever attacked by the fungus. The diseased 

 twigs should be cut back to the healthy wood, as it is not 

 possible to expect from it either the production of fruit 

 or of healthy wood. 



