550 Journal of Agricultural Research vol. vi, no. i S 



preceding by having a spathe that opens broadly, as well as by the 

 general aspects of the plants. C. indica (Lour.) Kunth, a native of 

 Java, was also used in these investigations. 



The storage of dasheens by piling the tubers and conns in the field 

 and overlaying them with straw and earth fully protects them against 

 freezes and yields itself readily in other respects to a successful handling 

 of the crop. In these piles, however, unless special means of ventilation 

 are provided, many of the tubers and corms rot so badly as to render 

 them useless for food or propagation. From such decayed material a 

 considerable variety of organisms was isolated during the winter of 191 2 

 and 1 91 3. From similar material about the same organisms were 

 isolated the following year. With these organisms inoculation experi- 

 ments were made during the winter of 191 3 and 191 4, and repeated 

 again in 191 4 and 191 5. Out of the different organisms isolated four 

 were found to be wound parasites under certain conditions. Macro- 

 scopically it is not always easy to distinguish the different rots, since in 

 some cases more than one of the rot-producing organisms may be present. 

 An accurate diagnosis is also frequently obscured or rendered difficult 

 by the invasion of saprophytic bacteria and fungi. Furthermore, the 

 striking similarity of some of the rots in the earlier stages renders a 

 diagnosis extremely difficult. While the writer can usually distinguish 

 macroscopically typical cases of the several rots in the later stages, the 

 only sure method is the preparation of cultures. 



JAVA BLACKROT 



The most common and destructive of the storage-rots is called the 

 "Java blackrot" because of its resemblance to the Java blackrot of the 

 sweet potato (Ipomoea batatas) caused by the same organism, Diplodia 

 tubericola. The causal fungus has been isolated repeatedly during a 

 period of three years from a number of varieties. This disease is par- 

 ticularly interesting in view of the fact that different species of the genus 

 Diplodia obtained from other hosts widely separated botanically from the 

 dasheen will cause a decay of the latter identical in character. 



DESCRIPTION OF JAVA BLACKROT 



The tissue when first invaded by the fungus is but little or not at all 

 changed in color and is soft, slimy, and stringy. The substance of the 

 corm or tuber becomes pasty and will, if picked up by the forceps, draw 

 out in a threadlike manner. It is often difficult to distinguish the decay 

 caused by the blackrot fungus in the early stages from the decay pro- 

 duced in the initial stages by other organisms without resorting to plate 

 isolations. A little later, however, the tissue becomes slightly pinkish 

 and then gradually turns black, and in this respect differs from the decayed 

 tissue produced by the other organisms. At the same time the rotted 

 portion of the tuber gradually becomes firmer by the escape of moisture. 



