182 PYTHIUM DISEASE OF GINGER, TOBACCO AND PAPAYA 



vau Breda, He failed to get successful inoculations on healthy tobacco plants. 

 He did not give any details of the fungus, bat only mentioned that he did not 

 find any septum cutting off the sporangial stalk. Since Pythium gracile 

 de Bary was previously only known as a saprophyte, he suggested for the first 

 time the facultative parasitism of this species. 



In July, 1917, seedlings of chillies {Capsicum annuum) were found to damp 

 ofE in small quantities. The seeds were got from Bombay. The same Pythium 

 was found to be the cause here also. 



About the same time, a small ginger plant {Zingiber officinale) was found 

 dying in a plot where ginger rhizomes were planted for experiments. The 

 portions above the ground-level were withered. The collar had become very 

 soft and rotten. On examination numerous oospores of a Phycomycete were 

 jound in the rotten leaf-sheaths at the collar. The oospores were smooth, 

 thick-walled, and lying loose in the oogonium. Pieces of the rotten stem were 

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

 with numerous sporangia of a Pythium belonging to the gracile group developed. 

 Later on oospores also were produced, and these oospores agreed with those 

 found on the plant itself before. This fungus was found to be identical with 

 that causing " damping off " on tobacco and chillies. Pure cultures were 

 taken in the same way as in tobacco. 



Butler has previously mentioned^ that a species identified as Pythium 

 gracile Schenk (not de Bary) causes a serious disease of ginger plants near 

 Surat (Bombay). It was pointed out, however, that it is not now possible 

 to be quite certain what fungus Schenk had under study, as he did not describe 

 it fully and there are several allied forms difficult to distinguish from one 

 another. The symptoms by which the disease can be recognized are a wither- 

 ing of the leaves and a softening of the stalks at the collar though not to such 

 a degree as to make them fall over. Specimens preserved in the Pusa Her- 

 barium show that the Surat fungus agrees with that now under consideration. 

 It was not cultivated and no inoculations were carried out. 



A form found killing castor plants {Ricinus communis) in water culture 

 in India^ is perhaps the same. 



In 1908-09 McRae^ investigated a disease of ginger in Rangpur (Eastern 

 Bengal) locally called " Jaindhara " and identical with the Surat disease. 



^Butler, E. J. "An account of the genus Pythium and some Chytridiacese."^" .Mem. 

 Dept. ofAgric. in India, Bot. Ser., I, No. 5, 1907, p. 70. 



2 Ibid. 



3 McRae, W. " Soft rot of ginger in the Rangpur District, Eastern Bengal." Agric. 

 Journ,of India, VI, 1911, pp. 139-146. 



