lll 
station at Clifden, Co. Galway, which during its short existence 
has contributed so much to our knowledge of potato diseases, and 
partly in Dublin. 
The Vertzcillium potato disease was described by Reinke and 
Berthold as long ago as 1879, and was stated by them to be the 
cause of the well-known malady of potatoes known as ‘‘ Leaf Curl.’’ 
Since then many workers have investigated the “ Leaf Curl ’’ 
problem, and a mass of literature has accumulated which is, how- 
ever, of a most confusing and conflicting nature. The various 
writers have attributed utterly different fungi as being the cause 
of “Curl’’ and the allied ‘‘Leaf Roll”? (in England Macro- 
sporium Solani was usually considered mainly responsible), while 
others vigorously maintained that the disease was non-parasitic, 
_ and due to physiological disturbances in the plant. 
g. 8 
“Curl’’ disease in the British Isles. Pethybridge finds that, in 
the main, Reinke and Berthold were correct, but shows that 
“curl”? is not by any means a constant feature of the Verticillium 
disease. He also corrects several errors made by them, and shows 
how the difficulties and discrepancies they encountered may be 
explained. 
The mycelium of the fungus is found in the vascular bundles 
only, and it is confined in them to the wood vessels. With the 
sprouting of the tuber the mycelium passes along the vessels 
mto the new shoots, though sometimes not until the latter have 
made considerable growth. Hence though the potato plants may 
often show the typical symptoms of Verticillium, no mycelium 
will be found in the stem, except at the extreme base. In later 
stages the mycelium may advance up the shoots and be traced in 
the vessels of the petioles and leaves, though in cases of bad infec- 
tion the water-conducting tissues become so blocked that the 
plants wither and die off early in the season. 
From the base of the shoots the mycelium also passes into the 
wood vessels of the rhizomes and from these into the new tubers. 
P ethybridge’s experiments show that, contrary to the view held 
by Reinke and Berthold, the mycelium, even in the autumn, pene- 
that no reliance can be placed on the absence of a dark ring in 
the tuber as a proof of clean seed. 
cultures were successful in reproducing the disease. In the field 
ti under natural condi- 
aaa — controlling the disease clean “ seed ’’ is, of course, 
ntial. . : 
An attack of Verticillium.albo-atrum resulta in the more or less 
Premature death by desiccation of the plant owing to the choking | 
