694 



ductive system due to very different causes but especially frequent in root 

 diseases. It appears also very clearly in the pineapple disease, in a parasitic 

 disease of the sugar cane produced by Thielaviopsis cthaceticus which can 

 be transmitted by cuttings. The greater the amount of sugar in the stem — 

 this increases constantly from the base up to about the middle of the stem — 

 the more easily the cuttings become diseased by the fungi\ The red color 

 appears in the Sereh disease at times isolated in some nodes, while the fibro- 

 vascular cords of the underlying internodes are still uncolored. It may be 

 concluded from this that the disease represents a general ailment, a constitu- 

 tional disease, which shows its first visible symptoms in especially weakened 

 places. 



The cause of the disease has been sought in all kinds of influences ; 

 exhaustion of the soil, degeneration due to continual asexual propagation, 

 abnormal atmospheric conditions, unsuitable fertilization, especially with 

 peanut meal (Bungkil), too deep planting, or too high covering with earth, 

 too early, or too late planting, and finally parasites. Among the latter, 

 nematodes, fungi and bacteria come under consideration. 



The conclusions of one scientist contradict those of another. Thus, 

 for example, Kriiger states that he has found bacteria in the ducts as a 

 constant accompaniment of the disease, while Tschirch- considers it impos- 

 sible that bacteria can be the cause of the disease and sees the initial stages 

 in an injury to the roots. Benecke^ sides with Kriiger, Mobius* opposes the 

 assertion of any existing degeneration and also seeks the cause in parasitic 

 organisms. OhP perceives the cause of the Sereh disease and the disease 

 of the coffee tree in Java, in which the leaves fall, to be the deforestration of 

 the mountains and subsequent drought. Janse*, in the same way, traces the 

 disease to a lack of water, since he thinks that the gummy obstruction of 

 the ducts prevents conductivity. He connects the formation of the gummy 

 substance with bacteria (Bacillus Sacchari). Went'' considers the Sereh 

 directly as a gummosis which arises from the co-operation of a parasitic 

 root and leaf sheath disease and which may be propagated by cuttings. 



Wakker* considers the disease as a non-parasitic gummosis, associatetl 

 with the excess of water which cuttings, developing during the dry monsoon, 

 suffer in the following rainy period. 



1 Cobh, N. A., Fungus Maladies of tho Sugar Cane. Rop. Exp. Stat, of the 

 Hawaiian Sugar Planters' Association. Bull. T>, Honolulu, 190fi, Part 1, p. 218. 



2 Tschirch, A., Vtaer Sereh, die wichtigste aller Krankheiten des Zuckerrohrcs 

 in Java. Schweiz. "Wochenschrift f. Pfarmazie 1891. 



3 Benecke, Franz, Proefnemingen ter Bestrijding der "Sereh." Samarang 1890. 

 For further treatises by this author cf. Zeitschr. f. Pflanzenkr. 1891. p. 3.'^4, 361. 



4 Mobius, M., Over de gevolgen van voortdurende vermcnigvuldiging der 

 Phanerogamen langs geslachteloosen weg. Mededcelingen van het Proefstation 

 "Midden Java" te Samarang. 1890. 



s Ohl. A. E., Eene Waterstudie. Batavia 1891; cit. Zeitschr. f. Pflanzenkrankh. 

 Vol. I, p. 365. 



B Cit. Zeitschr. f. Pflanzenkrankh. 1893, p. 238. 



7 Went, F. A., Die Serehkrankheit; cit. Zeitschr. f. Pflanzenkrankh. 1894, ji. 

 235 and 1901, p. 297. 



8 Wakker, J. H., De Sereh-Ziekte S. A. Archief voor dc Java-Suikcrindustrie. 

 1897, Afl. 3. 



