H. WORMALD 177 



Schellenberg writes 1 , "Auch die Specialisation des Pilzes ist, wie mir 

 scheint, eine weitgehende, denn der Pilz geht nicht auf die nahe ver- 

 wandte Quitte iiber und wie es scheint auch nicht auf Crataegus, Pirus 

 malus und communis und Primus Padus, avium und cerasux." 



On the other hand the writer found on one of the medlar trees a 

 mummified flower bearing three pustules of Monilia cinerea and also 

 a leaf with numerous pustules of the same fungus; the medlar therefore 

 under certain conditions may serve as a host for Sclerotinia cinerea and 

 so become a source of infection for neighbouring plum and cherry trees. 



Summary. 



This article records the occurrence, in the spring of 1920, of the 

 conidial form of Sclerotinia Mespili Schell. on the leaves of medlar trees 

 in four localities in Kent and one in Somersetshire. 



Mycelium obtained from dead flowers which had remained on the 

 tree from the previous year gave rise to cultures similar to those obtained 

 from conidia taken from infected leaves but the Sclerotinia stage of the 

 fungus was not observed. 



DESCRIPTION OF PLATE XI 



Fig. 1. A young flowering shoot of medlar showing three infected leaves ( Xg). 

 Fig. 2. A diseased medlar leaf showing the conidial fructifications extending along the 

 mid-rib and chief veins of the infected portion ( X §). 



1 L.c. p. 195. 



