HOWARD AND HOWARD 17 
exceedingly badly wilted, complete recovery took place in March 1919, when 
the stunted diseased individuals which had been looked upon as dead, threw 
out vigorous healthy shoots. 
Conclusions. 
These are the facts relating to the occurrence and production of wilt so 
far as they have been ascertained under Bihar conditions. The conclusion 
is irresistible that the trouble results from the destruction of the roots and 
nodules under circumstances when regeneration is impossible. Under estate 
conditions, the indigo crop, with very rare exceptions, does well till the first 
cut. This operation, however, destroys the fine roots and nodules, and before 
new growth can take place root regeneration is necessary. If the soil aeration 
is sufficient at this period, the plant shoots well and, provided these conditions 
continue, as in 1919, an excellent second crop follows. If, however, at the time 
of the first cut, floods cause the ground water to rise and if heavy rain water- 
logs the surface soil for long periods, root regeneration is very difficult and 
the result is wilt and a poor second cut. The wilt which often attacks old 
indigo in November and December is due to the fact that this plant has been 
forced to develop surface roots in the late rains. These suffer from want of 
water as the ground dries after the monsoon and the advent of the cold 
weather prevents the formation of more roots. 
Confirmatory evidence. 
If our view of the cause of wilt is correct and if the aeration of the soil is 
really defective in Bihar during the second half of the rainy season, several 
consequences naturally follow. Firstly, wilt should not be confined to Java 
indigo, but should affect other deep-rooted plants while surface-rooted species, 
on the other hand, should escape. In the second place, as two rainy seasons 
in India are never the same and long breaks occur, soil aeration in Bihar in 
August and September should occasionally improve and lead to the recovery of 
wilted plants and to greatly increased crops of indigo. In the third place, 
indigo wilt should not occur in other localities provided the soil ventilation is 
efficient during the whole of the monsoon phase. Confirmatory evidence has 
been obtained in all these directions. 
Wilt in Bihar during the monsoon is by no means confined to Java indigo. 
It is common on many deep-rooted varieties of patwa (Hibiscus cannabinus 1.) 
and sann (Crotalaria juncea 1..) while shallow rooted types of these two species 
are little affected. Further, surface-rooted species like Roselle (Hibiscus 
Sabdariffa L.) thrive no matter how wet the monsoon may be. The differ- 
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