356 [ T PLUM 



form cracks along which the tissues are reduced to a 

 brownish mass. 



The roots are liable to two forms of root-rot, that 

 caused by Armillaria mellea Vahl, and that due to the 

 presence of Dematophora necatrix Hart, which is hardly 

 less dangerous and is manifested by a close network of 

 white or whitish mycelium which covers the root and 

 destroys the woody tissues reducing them to a soft and 

 brown mass. Fomes fulvus Fr. is a frequent cause of 

 dry rot on the stems and branches of our plum trees, and 

 this species is replaced on the continent by two other dry 

 rot fungi, viz: Poiyporus ignarius Fr. and P. nigncans Fr. 



The plum is subject to harbour several species of 

 Aphis, viz : (a) Aphis Pruni Fb. of which the wingless 

 insect is oblong and of a light green colour, covered by a 

 white powder, (b) A. Persicae Sulz. the wingless insect 

 being light green, and then dull green, and finally 

 greenish yellow with tranverse black lines, (c) A. Insi- 

 titiae Koch, of which the wingless insect is reddish or 

 rust colour with a dark brown back, (d) A. Humuli Schrk. 

 the wingless insect of which is light greenish yellow with 

 a deep green line on the back A. PrumK.och. (non Fb.) 

 of which the wingless insect is oblong and green with 

 black markings. The first two species are sometimes met 

 with on our plum trees, and they may cause some injury 

 to the foliage as well as to growing twigs, but an attack 

 of Aphis on the plum is far from being so dangerous as 

 in the case of the peach and nectarine, and the treatment 

 may be carried out on the same lines as suggested 

 for the peach. 



The erinosis of the plum, a rare disease in our or- 

 chards is due to Phytoptiis phlaeocoptes Nal. In Italy small 

 galls in the shape of nodules are formed on the leaf and 

 especially along its margin by Volvulijex Pruni Am,, 

 and tiny bottle-shaped red galls on the upper surface of 

 the leaf are caused by Bursifex Pruni Am. Along the 



