Pflanzenkrankheiten. — Bacteriolo^ie. 39 



& j 



in Surinam. (Journ. Bd. Agric. Brit. Guiana. X. p. 93—103. 

 1917.) 



A comparison of Hevea plantations in Surinam and British 

 Guiana, especially with reference to the leaf disease caused by 

 Fusicladium macrosporum Kuyper. This disease is very widespread 

 and virulent in Surinam, so much so that the cultivation of Hevea 

 in that colony threatens to become unremunerative, and the Substi- 

 tution of coffee is being advocated. Conditions in British Guiana 

 are not at present so bad. The fungus has spread to cultivated 

 Hevea from wild species of Hevea growing in the forests. As the 

 eradication of wild Hevea is impracticable, remedial measures must 

 be directed to destroying diseased leaves in the plantations. It is 

 suggested that „smoking", to cause defoliation without injury to the 

 young shoots, may prove an effective method of getting rid of 

 diseased leaves. Spraying is useful when the attack is lieht. 



E. M. Wakefieid (Kew). 



Hutchinson, C. H. and N. V. Joshi. Bacterial Rot of stored 

 Potato Tubers. (Mem. Dept. Agric. India. Bacteriolog. Series. 

 I. N° 5. p. 113—135. 5 pl. 1915.) 



The authors investigated the rotting of stored potato tubers in 

 India, and succeeded in isolating four species of bacteria capable 

 of causing rots. 



Of these four only the one described as N° 1 was invariably 

 present, N° 2 was less frequent, and N 08 3 and 4 rare. 



Infection takes place from outside the tuber, through wounds 

 or under damp conditions. The bacteria are unable to penetrate 

 the skin of perfecta sound, dry tubers. 



Preventive measures consist in avoiding injury to the tubers, 

 storing them dry in dry sand or other similar material, and perio- 

 dical inspection of the stored tubers to remove rotting specimens. 

 Treatment of the outside skin with 2% copper sulphate Solution 

 was found successful in preventing rotting, provided the stored 

 tubers were kept under perfectly dry conditions. 



E. M. Wakefieid (Kew). 



Bpeslauer, A., Recherches sur l'applicationdureactifde 

 Chodat paracreosoltyrosinase ä l'etude de la proteo- 

 lvse par les microorganismes. (Bull. Soc. bot. de Geneve. 

 2me ser. VIII. p. 319—352. 1916.) 



Les differentes especes microbiennes peuvent etre differenciees 

 colorimetriquement au moyen du reactif Chodat. La vitesse et l'in- 

 tensite de la reaction dependent de la quantite de culture en presence, 

 de l'äge de cette culture. Ces fonctions varient avec chaque espece 

 des bacteries. La nature du milieu de culture infiuence la reaction. 

 II y a paralelisme entre la teinte obtenue et la quantite de gelatine 

 liquefiee en presence, ce qui parait indiquer l'existence d'une gela- 

 tinase. La lumiere n'influence que peu la reaction. Celle-ci se pour- 

 suit dans l'obscurite. Les basses temperatures extravent considera- 

 blement le developpement de la reaction. Le reactif de Chodat 

 constitue un reactif de l'indol, avantageusement approprie" aussi 

 bien ä deceler la presence de traces de ce compose qu'ä sa Separa- 

 tion de son homologue le scatol. Les microorganismes, extraits du 

 fromage soumis ä l'experience, se comportent, pour la plupart, dif- 

 feremment vis-a-vis de la caseine, du lait et vis-ä vis de la caseine 



