PESTS OF OE CHARD AND FRUIT GARDEN. 



15 



The threads are short and rather robust, and the conidia are typically 

 rather fusiform, being attenuated towards each end (28-30x7-9 /*), 

 and we have never met them with a transverse division, whereas those of 

 the Pear scab are usually of a club shape, and often divided into one large 

 cell and one small one. 



Known in Germany, Austria, Italy, Portugal, and France. 



For remedies see also Apple Scab. 1 



Sacc. Syll. iv. 1643 ; Mass. PL Dis. 304, fig. 81. 



A mould with fusiform conidia, not unlike Fusarium, is recorded as 

 affecting ripening Pears in France. It has been named Discocolla pirina. 



Ameeican Pear Blight. 

 Micrococcus amylovorus (Burr.), PI. X. fig. 25. 



Pear blight, or fire blight, is known only in North America, and was 

 first observed in 1780, but no description of it until 1817. " It frequently 

 destroys trees in the fullest apparent vigour and health in a few hours, 

 turning the leaves suddenly brown, as if they had passed through a hot 

 flame, and causing a morbid matter to exude from the pores of the bark 

 of a black ferruginous appearance." The results of epidemics have been 

 most disastrous, especially the memorable year of 1844. 



Various conjectures have been made as to its cause, the last of which, 

 the bacterial, advocated by Professor Burrell, was supported by a long 

 series of experiments by inoculating healthy branches with the juices of 

 diseased ones and producing the disease, since which time the experi- 

 ments have been confirmed. 



The organism named Micrococcus amylovorus consists of single cells, 

 of oval or roundish shape (1—1 J x J-f ju) and quite colourless. For the 

 most part they remain single, but may often be found in pairs, rarely a 

 series of four or more, but never extending to chains. 



Sacc Syll. viii. 3887; Amer. Nat. xvii. 1883, p. 319; Arthur, 

 History and Biology of Pear Blight, 1886, plate ; Grove, Syn. Bact. p. 10. 



Medlar Cluster-cups. 

 Mci&ium mespili (DC). 



This species of cluster-cups appears now to be recognised as distinct 

 and alone, without Uredo or Puccinia to keep it company. It is only 

 reported to occur on the leaves of Mespilus and Cotoneaster. 



Rounded or irregular spots are formed upon the leaves, which are 

 yellowish or reddish on the upper side, with a yellow border, thickened in 

 the centre. The cups are cylindrical, splitting at the edge into narrow 

 teeth or threads. iEcidiospores angular (19-24 [x diam.), very minutely 

 warted and brown. 



There is a suspicion of this species having been found in Britain, but 

 it evidently has never given any trouble as a pest. It occurs also in 

 France and in Germany. 



Sacc. Syll. vii. 2773 ; Plowr. Br. Ured. p. 232 ; Mass. PL Dis. 258. 



