DISEASES OF VARIOUS CROPS T713 



by gathering together and burning the infected stalks and leaves. The 

 damage caused b}^ the disease is comparatively insignificant. 



In the same paper there are reports of two cases of Ustiilina zonata 

 on rubber at Deli (Sumatra). 



In the Federated Malay States this fungus does a great deal of harm 

 in rubber plantations as sharples has recently stated (i). It attacks 

 the wood, having effected its entrance by means of the holes made b}' min- 

 ing insects or by other wounds. This disease is probably very contagious. 



As a means of prevention the writer advocates the removal of all dead 

 wood that could shelter insect pests from the plantation. 



12^^ - Botrytfs (cinerea?) and Rhizopus {nigricans'}) as the cause of Rot 



in Strawberries in the United States. — Stevens, N. E., in journal oj Aoricultiiral 

 Research, Vol. VI, No. 10, pp. 361-366, PI. XEIX-I^. Washington, D. C, 1916. 



Strawberries sent out from the Southern States are very often spoilt 

 by Botrytis {cinerea?) and Rhizopus {nigricans?), which cause rot during 

 shipment and on the market. The pathological processes are very differ- 

 ent in the two cases. 



Botrytis sp. — The mycelium penetrates into all parts of the berry 

 it fills up the intercellular spaces with a network of hyphae which surrounds 

 the cells and tissues so that the berry keeps its shape and only undergoes 

 a slight shrinkage without much loss of juice. 



The hyphae readily dissolve the middle lamella and are able to pene- 

 trate into the cells where they very quickly bring about the disintegration 

 of the proptoplasmic contents so that the nucleus can no longer be dis- 

 tinguished. 



Rhizopus sp. — The berries become flattenend and there is a consid- 

 erable loss of juice. The mj^'celium of the parasite normally develops qviite 

 near the surface of the berry in the outer 6 or 8 cell layers, and only very 

 rarely does it make its way into the cells. 



The nuclei of the cells persist in apparently normal condition until 

 the cytoplasm has almost entirely collapsed. Under very dry conditions 

 (a dessicator with concentrated sulphuric acid) Rhizopus sp. develops to 

 such an extent that it extends to the middle of the berry; in tliis case the 

 h3'^phae are often found inside the cells. 



It is rare to find both parasites in the same berry. But often Botrytis 

 sp. is found with Fusarium sp. or with AUernaria sp., or Rhizopus sp. 

 is found with Fusarium sp. In these cases the two mycelia mingle in the tis- 

 sues of the berry, but they may also occupy two distinct zones with a marked 

 line of division as is the case with Botrytis sp. and AUernaria sp. 



It is possible that Rhizopus sp. can occur in a region originally infect- 

 ed by Botrytis sp. or by some other fungus. The writer's researches how- 

 ever point to the conclusion that Rhizopus sp. is not dependent upon 

 the presence of any other fungus in its attacks on strawberries during ship- 

 ment or on the market. 



(i) See B. July, iyi6, N" 812. [Ed.) 



