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A PYTHIUM DISEASE OF GINGER, TOBACCO 

 AND PAPAYA. 



LIBRARV 

 BY NEW YORK 



gpTANlCAL 



L. S. SUBRAMANIAM, ■a/^l>fiW 



Assistant to the Imjierial Mycologist. 



[Received for publication on llth June, 1919.] 



About three years ago, seedlings of tobacco {Nicotiana Tahacum) were 

 found to damp off in large numbers in the seed beds. A few seedlings were 

 incubated in a moist chamber. The next day there was a copious growth of a 

 Pythium belonging to the gracile group (subgenus ApJiragmiwn). It had the 

 following characteristics : — Mycelium branching freely in all the tissues ; 

 hyphae 3 to 8/x broad, septate in the older branches and frequently with ir- 

 regular swellings on the hyphse, sporangia produced in large numbers, lateral, 

 elongated, similar in shape to the hyphse, slightly swollen at the tip when ripe, 

 without a septum cutting off the sporangial stalk from the parent hypha ; 

 zoospores of the usual Pythium type ; oogonia with oospores not completely 

 filling the cavity, produced on lateral branches and on the hyphal swellings both 

 intra- and extra-matrically. Boiled ants were floated in a dish of water 

 and a piece from the incubated material was put in the dish. On the third day 

 there was a good growth of the fungus on the ants. One of the ants con- 

 taining the mycelium of the fungus was put in a glucose agar slant. The 

 fungus grew well in this medium and subcultures from it gave pure cultures. 



Raciborskil found a fungus, which he identified as Pythium co)npIens 

 Fischer (which is the same as P. gracile de Bary and cannot be distinguished 

 from the earlier P. monospermum Prings.), attacking tobacco plants in nurseries 

 which were weakened previously by the attack of Phytophthora NicotiancB 



1 Raciborski, M. Parasitische Algen und Pilze Java's, 1 Thiel, p. 8, 1900. 

 ^ ( 181 ) 



