FUNGOID PESTS OF CULTIVATED PLANTS. 135 



abandoned in several parts of the country where formerly there were large 

 and profitable orchards." The earliest symptom is the premature ripen- 

 ing of the fruit ; then diseased dwarfed growths appear on the trunks 

 and limbs. The limbs attacked are badly diseased the second year, the 

 entire growth being stunted and of a sickly green tinged with yellow. 

 After this they may languish for a few years, and then die gradually from 

 the extremities downwards. All efforts to discover fungoid mycelium has 

 failed, and it is only recently that the disease has been attributed to 

 microbes. In 1889 Professor Burrill intimated that he had found " in 

 the tissues of the root and of the old and young stems of diseased trees 

 an organism classed with the bacteria which is not known to occur else- 

 where. This organism has been frequently obtained by method of 

 cultures under circumstances which preclude the possibility of its corning 

 from anything except the inner cells of the tree. He had it growing in 

 artificial media, and it exhibited all the peculiarities of a pathogenic 

 rather than a saprophytic microbe. He found it in every set of specimens 

 which he examined, known to be affected by the disease, and has thoroughly 

 tried in the same manner to find it in healthy stock and failed." 



ALMOND TWIG FUSICOCCUM. 

 Fusicoccum Amygdali (Del.). 



This disease has appeared in France, as pustules on living twigs 

 of Almond-trees, breaking through the bark, and dispensing conidia 

 6 7J x 2J 3/7, allied to those of the common red Tubercularia. 



Bull. Soc. Myc. de. Fr. xxi. fasc. 3, p. 180, fig. 4. 



SILVEK LEAF. 



Stereum purpureum (Fries). 



This disease has been known as affecting fruit trees in this country for 

 fully a quarter of a century, and has puzzled mycologists and pathologists 

 to account for the cause. Recently Professor Percival has conducted 

 some experiments which he considers will demonstrate that the disease 

 is caused by a wound parasite, which in its fully developed form is a 

 hymenomycetal fungus called Stereum purpureum. 



At the same time it has been affirmed on good authority that several 

 Horse Chestnut trees in Greenwich Park have been killed by attacks of 

 this same fungus, which has, at any rate, been developed freely on the 

 dead bark. 



Attacks Plum, Peach, and Apricot trees. 



We must still regard ourselves as sceptical as to whether the Stereitm is 

 the cause of "silver leaf," or the presence of too much nitrogen in the soil. 



Sacc. Syll. Hym. ii. 7284 ; Cooke Hdbk. No. 910 ; Journ. Linn. Soc., 

 Bot. xxxv. p. 390, pi. x. 1902 ; Journ. E.H.S. xxvii. (1902), p. 712 ; 

 xxviii. 1904, p. clxxiv ; Gard. Chron. Aug. 12, 1905, p. 111. 



APEICOT BEOWN ROT. 

 Monilia fructigena (Pers.), PI. X. fig. 12. 



This disease attacks indiscriminately a number of pulpy fruits, the 

 Apple and Pear in this country, and the Cherry and Apricot in the 



