Albert Howard 



381 



surface-rooted species like "Roselle" (Hibiscus Sabdariffa L.) thrive no 

 matter how wet the monsoon may be. The roots of Roselle in wet years 

 exhibit marked aerotropism leaving the soil and growing all over the 

 surface of the ground. The differences between the distribution of the 

 roots of Roselle and of deep-rooted types of patwa are shown in Fig. 3, 

 while in Fig. 4 the roots of an early and late type of patwa are illustrated. 

 The surface-rooted Roselle crop and the early types of patwa do well at 

 Pusa even if the soil becomes waterlogged occasionally. The deep-rooted 

 types in such seasons, on the other hand, suffer severely from wilt. In 

 such cases, the fine roots are destroyed from below upwards and the 

 details follow closely those already described in the case of Java indigo. 



Fig. 4. Early (left) and late (right) types of root-systems in H. cannabinus. 



Similar results have been obtained at Pusa in the case of two varieties 

 of sann hemp (C rotatoria juncea L.). The local Bihar variety with surface 

 roots sets seed but the deep-rooted tall variety from the black soils of 

 the Central Provinces suffers from wilt and various insect diseases and 

 hardly yields any seed crop. 



The wilt diseases so far dealt with result from the slow destruction 

 of the active root-system which follows the cessation of drainage and 

 aeration during the rains. No parasite appears to be involved in any of 

 these diseases. The remainder of this paper deals with diseases in which 

 either insects or fungi are concerned, but in every case the actual attack 

 follows the operation of some injurious factor such as poor soil-aeration, 



