PLANT DISEASES OF CONNECTICUT. 357 



less circular depressed areas of decaying tissue, varying consider- 

 ably in size. They are light brown and corky, and are generally 

 surrounded by a well-defined purple margin. As the disease 

 advances, these patches crack and form deep fissures, which spread 

 deeply into the interior of the turnip, ruining it. Numerous 

 black dots (pycnidia) now appear on the diseased patches ; these 

 dots are cone-shaped, and contain immense numbers of minute 

 spores, which emerge from the apices of the fructification in 

 small, globular, rose-colored masses. The spores then soon 

 separate, and are disseminated by various agencies, especially 

 wind." 



In 1912, Giissow (2) reported the disease from Prince Edward 

 Island, Canada, and this seems to be the first report of the dis- 

 ease from North America. While we have accepted Rostrup's 

 name for the fungus, we are not sure whether it is distinct 

 from a cabbage fungus (Phoma Brassiccz, or P. oleracea) that 

 has caused more or less damage in Europe and was reported in 

 1911 by Manns (Ohio Agr. Exp. Stat. Bull. 228: 276-89) as 

 causing serious injury in Ohio, especially through cankers on 

 the stems. The cabbage and turnip both belong to the same 

 genus, and so are closely related, and the Phoma fungi found 

 on each cause cankers, and have spores about the same size. 

 (Manns reports the spores of the cabbage Phoma as 4.5-5^ x 

 1.7-2/1,, while those of our turnip Phoma are chiefly 3. 6-4.5/11 x 

 i.Sfi). But we do not know whether the spore masses of the 

 cabbage Phoma are rose-colored, as are those of the turnip 

 Phoma. Manns reports the fungus as occurring on the leaves 

 somewhat, and McAlpine reports it on the leaves of cabbage, 

 turnip and rape. Johnson has reported a Phoma disease on the 

 leaves of Swede turnip in Ireland, and this may be the same 

 as our Phoma. The other writers do not distinctly mention the 

 Phoma as occurring on the leaves of turnips, though from the 

 spraying treatment recommended, it is at least suggested that it 

 may occur there. 



While the different investigators have suggested various pre- 

 ventive treatments, it is not known yet whether all of these are 

 practical, especially the spraying of the foliage in the field. 

 Certainly, however, rotation should be practiced where the dis- 

 ease has appeared in a field. It is also quite likely that the kind 

 and amount of manure used in the field may have some influence. 



