CHAPTER II. 
NEOCOSMOSPORA VASINFECTA SMITH. 
The above experiments, except Series IV, were carried out 
at Dehra Dun where the Mycological Laboratory of the Indian 
Department of Agriculture was then situated, and the material 
used was all obtained in that locality. Series IV was carried out 
at Poona. As they were evidently unsatisfactory, work was con- 
tinued at Pusa in 1907-08. The pigeon-pea wilt is common in the 
vicinity and provided abundant material for investigation. 
Karly in 1907 perithecia of the well-known fungus Neocosmo- 
spora vasinfecta were discovered on the roots of wilted plants. As 
a large proportion of the wilt diseases of plants hitherto mvestig- 
ated has been attributed to forms of this fungus, the discovery 
was significant, and further search showed that most of the dead 
roots examined either already bore these perithecia or could be 
induced to produce them by incubation in a moist atmosphere. 
The most careful search carried on for two years at Pusa and other 
localities in the plains of India has been unsuccessful in finding the 
Nectria met with at Dehra Dun on this host.’ On the other 
hand, Neocosmospora vasinfecta has been found on pigeon-pea 
roots from Dehra Dun and has proved to be widely distributed 
throughout Northern India. 
This fungus was first described by E. F. Smith (2) in the 
United States, in connection with wilt diseases of cotton, water- 
melon and cow-pea. The symptoms in all three diseases were 
1 This is not proof that it does not occur in its lower (Cephalosporium and Fusarium) 
stages, The Erysiphaceg of the plains are common enough in the conidial stage, but perithecia 
are rare and in some species are apparently not formed. In the more temperate parts (as in 
Kashmir) perithecial forms of Erysiphacee are common, It is quite possible that the tem- 
perate climate of Debra Dun favours the production of perithecia in the pigeon-pea Nectria, 
whereas the heat of the plains checks this stage and forces the fungus to reproduce by means 
of conidia alone, 
