181 



Report on the "Black rot" disease of Ginger from Jamaioa. 

 The rhizomes show dark areas which contain the mycelium of a 

 iungus in which numerous black chlamydospores are produced, fre- 

 quently in chains. I have placed some of the material in a moist 

 chamber in the hope of getting some more definite spore formation. 

 The mode of formation of the chlamydospores resembles that seen in 

 Wakker's Allantospora radiicola which causes a root disease of the 

 sugar cane in Java, and in other fungi which attack plants under- 

 . ground 



It is impossible to say whether the fungus in the old rhizomes is 

 the cause of the disease or not. A more definite opinion could be 

 given if specimen of the roots and rhizomes of plants in which this 

 disease is just showing itself could be examined. It is hoped that it 

 will be possible to collect and forward such specimens which should be 

 placed in methylated spirit as soon as the plants are lifted 



The fungoid diseases of Ginger do not seem to have been investi- 

 gated A wilting disease of Ginger occurs here and in St Lucia but 

 " black-roi" and " cork-rot" do not seem to be common. I hope Mr. 

 Harris will be able to send specimens of "cork-rot" especially as the 

 damage done by this disease appears to be so considerable. 



The measures taken by the cultivators in Jam lica to prevent the 

 spread of ' black rot' seem to be very intelligent In addition to these 

 it might be useful to treat the affected soil with lime or with a light 

 dressing of sulphate of iron and when the diseased patch is large to 

 separate it before treatment, from the rest of the field by means of a 

 shallow trench as it would seem that disease spreads under ground. 



It would also be desirable if an experiment were made preferably 

 on a field in which ' black rot' has appeared, in which the rhizomes 

 used for planting were washed with water and then steeped for 

 half-an-hour in Bordeaux mixture. The resulting crop and its free- 

 dom from disease should be compared with that from an equal area, 

 say half an acre, in which the rhizom s have been untreated. The 

 results of such an experiment would be of great interest and value to 

 this Department. 



The very greatest care should be taken not to plant any rhizomes 

 which show traces of disease or those from disease! fields. Mr. Or id- 

 wick might refer to these points in his lectures to the people. 



A. Howard, 28. 10. '01. 



Imperial Department of Agriculture for the West Indies. 

 Instructions for collecting and forwarding specimens of Plants attacked 



by Fungoid Diseases. 



1. Specimens of plants attacked by fungoid pests are constantly 

 being received by the Department for examination and r >port. Much 

 labour and time is often wasted over these for want of knowledge on 

 the part of the senders as to what should be sent and ho v it should be 

 packed. This circular is issued with the object of giving information 

 on these points. 



2. When specimens of moist vegetable matter are packed in boxes 

 or sent in envelopes they speedily become covered with saprophytic 

 growths which frequently obscure all traces of the original cause of 

 disease and render the specimens worthless. This is especially the case 



