CONTRIBUTIONS FEOM THE WISLEY LABORATORY. 541 



CONTEIBUTIONS FEOM THE WISLEY LABOEATOEY. 



'ZIV. — On Some Plant Diseases new to, or little known in, 



Britain. 



By F. J. Chittenden, F.L.S. 



1. Lettuce Leaf Eot. . 



At the end of November last Mr. W. F. Emptage forwarded to me a 

 few small lettuce plants which had been sent to him from a garden 

 near Haslemere, SmTey, where they had been grown planted out on 

 fche borders in a glasshouse after a crop of tomatos. Their leaves 

 (especially, but not solely, the outer ones) had several small, round 

 or elliptical, brown, dead spots upon them. The spots were pale in 

 the middle, with a darker margin, and were from -| inch to ^ inch in 

 diameter. The tissues of these spots had in many cases dried up, 

 ^ leaving a more or less round hole. Several sunken areas of a similar 

 character were also present along the midrib. Where the attack had 

 resulted in many spots on the leaf the whole of it finally decayed. The 

 growth of the plants had been seriously affected, and about a quarter 

 3f the crop had been attacked. The variety was * Early French Frame 

 Forcing. ' 



Microscopic examina'tion of the affected areas showed the presence 

 of a fungus belonging to the genus Marssonia associated with each 

 of the spots, and agreeing in all its characters with a species first 

 described in 1896 on lettuce by Berlese,* and called by him Marsonia 

 Panattoniana, in honour of Dr. Guido Panattoni, of Lari di Pisa, who 

 first sent diseased specimens to him. 



The mode of attack described by Berlese was precisely the same 

 as in the plants sent to the Laboratory, and the severity of the attack 

 in Italy at that time was such that Dr. Panattoni had to report the 

 destruction of 2300 plants. 



There is no previous record of the occurrence of this disease in 

 Britain. SorauerI alludes to it as occurring in Italy alone. But the 

 fungus was reported in 1906 by 0. A. J. A. Oudemans^: attacking 

 lettuce and endive, and causing a leaf -rot of these plants in Holland; 

 and in 1907 by Appel and Laibach,|| causing a disease of cultivated 

 lettuce for the first time in Germany. The last-named authors grew 



* Dr. Antonio Berlese, " Un nuovo marcimne dell' Insalata (Lactuca 

 sativa) " in Rivista di Patologia Vegefale, III. (1896), pp. 339-342. 



t P. SoRAUER, Handbh. der Pflanzenkr. II. (Ed. 3), p. 429. 

 _ + C. A. J. A. OuDEMANS, " Contr. a la flore mycologique des Pays-Bas XX." 

 m Overdr. Ned. Kr. Arch. 3e Ser. II., 4 suppl. 



li 0. Appel and F. Laibach, " Ueber ein im Friihjahr 1907 in Salatpflan- 

 izungen verheerendes Auftreten von Marssonia Panattoniana Berl." in Anstalt 

 \fur Land- u. Forstwirts. VI. (1908), pp. 28-37. 



