THE GOOSEBEKRY MILDEW. 
139 
THE GOOSEBERRY MILDEW 
(Sphcerotlieca mors-iivcB (Schwein.) Berk. & Curt.). 
By Ernest S. Salmon, F.L.S. 
During last August I received from Mr. F. W. Moore, of the Royal 
Botanic Gardens, Glasnevin, some diseased Gooseberries. On examina- 
tion the berries were found to be covered with the brown scurf-like 
mycelium of a fungus— the American Gooseberry-mildew {Sphcerotheca 
mors-uvcB (Schwein.) Berk. & Curt.). This is the first record of the 
appearance in the Old World of this fungus, which has hitherto been 
known only from the United States. The particulars of the outbreak are 
as follows : — -The affected Gooseberries were sent to Mr. Moore by Mr. 
J. Nixon from the gardens at Whitehall, Ballymena, Co. Antrim. In 
answer to my inquiries Mr. Nixon kindly informed me that no plants of 
any kind had ever been introduced into the gardens from America, so 
there seems no reason to doubt that the fungus is indigenous. Mr. 
Nixon says : — " The outbreak is now very extensive, although the fungus 
only appeared on two trees at first. I observed it about the beginning of 
June in slight quantity, more especially on amber berries, but now there 
are none free entirely. We have now about forty trees almost covered 
with the fungus, which has attacked the leaves and stems as well as the 
berries." 
Parts of Gooseberry branches were sent by ]\Ir. Nixon, on which 
nearly every berry was attacked. The fungus forms on the berries dense 
matted brown patches, which at first are distinct from one another, but 
later become confluent and more or less completely invest the fruit. 
(Fig. 37.) This matted or scurf-like growth is the persistent myce- 
lium of the fungus, and is composed of numberless branched flexuous 
and interwoven brown threads or hypJicE. (Fig. 37.) Among these 
hyphae the perithecia are produced, each of which contains a single 
ascus, with eight ascospores. (Fig. 37.) 
In the United States the present disease is widely spread on cultivated 
and wild species of Bibes, and constitutes the most serious obstacle to 
the cultivation in that country of " foreign " varieties of the Gooseberry 
(i.e. those developed from the native Gooseberry of Northern Europe), as 
it is found that these almost invariably fall a prey to the mildew. 
Several American mycologists have treated of the disease. Halsted 
(1) gives a comprehensive account of its ravages in America, and in order 
to show the destructiveness of the disease gives the following extracts 
from the works of standard American authors on fruit-culture :— " The 
mildew of the Gooseberry is the most serious obstacle to the successful 
culture of the foreign Gooseberry in the United States. In the cool and 
moist climate of England it does not exist ; in the extreme northern parts 
of the Union it is not formidable ; but on approaching the Middle States, 
although the bushes grow vigorously and set abundant crops of young 
fruit, the latter becomes covered with a thick brown or grey mildew or 
scurf which destroys their value." " The mildew is the one great enemy 
