263 



ON A CASE OF RECOVERY FROM MOSAIC 

 DISEASE OF TOMATO. 



By W. B. BRIERLEY. 



(Laboratory of Plant Pathology, Royal Botanic Gardens, Keiv.) 



During recent years the attention of plant pathologists has been 

 increasingly directed to the study of certain diseases of obscure etiology, 

 which have for convenience been classed apart under the term " physio- 

 logical." Of these one of the most interesting yet least understood 

 is Mosaic disease, often known as "Frenching," "Calico" or "Mottle 

 Top," and found in a variety of plants chiefly members of the Solanaceae. 

 Great attention has been devoted to mosaic disease of tobacco, but 

 little focused on the study of this malady in tomato. In 1908, however, 

 Clinton 1 published the important fact that the mosaic disease of tobacco 

 is communicable to healthy tomato plants and vice versa; and this 

 conclusion, although opposed by Westerdijk 2 in an important paper 

 appearing two years later, is generally accepted. 



Excellent recent accounts of the past history and present position 

 of the question of mosaic disease will be found in the papers of Melchers 3 , 

 Allard 4 and Clinton 5 , and further discussion here is unnecessary. 



The interest of the present note lies in the exceedingly rare occur- 

 rence of recovery from the disease. 



In 1898 Beijerinck 6 stated, but without entering into any details, 

 that in some instances plants apparently showed a temporary recovery. 



Woods 7 , four years later, writes: "The mosaic nature of the trouble 

 and the fact that under some conditions the plants may grow out of 

 the disease." 



1 Rept. Conn. Agr. Expt. Sta. (1908). 



2 Mededeel. Phytopath. Lab. " Willie Commelin Scholten," Amsterdam, i. (1910). 



3 Ohio Nat. xrn. No. 8 (1913). 



4 Bull. Torr. Bot. Club, 41 (1914). 



5 Rept. Conn. Agr. Expt. Sta. (1914). 



6 Verhandel. Kon. Akad. Wetensch. Amsterdam, xi. 6/5 (1898). 



7 U.S. Dept. Agr. Bur. PI. Ind. Bull. 18 (1902). 



