Mycologisches Centralblatt, Bd. V, Heft 5. 
Ausgegeben am 19. Dezember 1914. 
Stagonospora Cassavae n. spec. 
by 
P. C. VAN DIR Wolk, Arnhem (Holland). 
(With 11 Textfigures.) 
1. In the early part of lastyear (1913), there appeared most unexpec- 
tedly in the Selection Garden at Buitenzorg a severe mould disease affec- 
ting the young slips of Cassava (.Manihot utüissima ). From the very begin- 
ning the disease was so virulent and progressed at once with such severity 
that the direst forebodings of an immediate and wide distribution of tliis 
sickness in the Cassava culture in Java appeared to be fuliy justified, 
seeing that vast quantities of selected Cassava material are distributed 
yearly from the Buitenzorg Selection Garden over the wliole of the Indian- 
Archipelago, and that the disease appeared to be axceptionally infections. 
Where the disease came from has remained an enigma tili now; so far 
as can be traced it was still unknown in the rest of Java and in the 
other islands. Since its appearance in the Selection Garden it has become 
quite habilitated, where it has become the greatest calamity which has 
yet befallen the Cassava plantations. Fortunately at the present time we 
have indeed completely succeeded in combatting the disease. The mould 
in question is a typical wound parasite; the seat of infection has tili now 
exclusively been that cut surface of the slip which is situated above ground. 
The disease is absolutely combatted by the tarring of these over-ground 
cut surfaces when the slips are set in the ground immediately after they 
have been cut. Further tests should decide whether or not in the course 
of time infection can take place via the ground also, and wliat then the 
consequences would be of tarring the cut surface of the slip situated in 
the ground. If through certain circumstances the slips do not come 
directly into the ground immediately after they have been cut it is cer- 
tainly of very great importance to very early well tar botli cut surfaces 
of the slip. Independantly of tliis however the necessary care should be 
taken that the slips are treated with some caution lest they sustain an 
unnecessary injury. In any case we may be thankful that this very 
dangerous Cassava disease has been able to be so quickly combatted in 
such an efficient and extremely simple way. 
2. The mould in question, which belongs to the Stagonospora -type 
and through its peculiar deviations has been brought under the heading 
of a new species, Stagonospora Cassavae, is pitch-black. It is a special 
destroyer of the wood elements in the body of the plant and spreads 
from the cut surface of the slip with incredible rapidity, by way of the 
woody elements in the bark and hast, over the scarcely opened buds and 
also over already old shoots, which acutely withered and go to ruin. Then 
^ the extension through the secondary woody part of the slip gradually 
takes place. 
In the course of time the small pitch-black round pycnides are for- 
med, which I shall return to presently. These pycnides are principally 
Mycologisches Centralblatt, Bd. V. 15 
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