26 THE RICE WORM (tYLENCHUS ANGUSTUS) AND ITS CONTROL 



1st, 1917. Owing to danger of infecting lower levels intended for paddy- 

 cultivation, the outlet to the water from the experimental area was kept closed. 

 Sowing was done at an unusually early date. The young seedlings w^ere 

 doubtless readily climbed by the worms during the first month of their growth, 

 since we know that the second growth shoots in infected fields that spring from 

 the stubble after harvest are commonly infected in January. The water from 

 the spring showers was held in the field, and though I am not in a position to 

 judge of the effect of this on the humidity within the crop, it can hardly have 

 been without some effect. I am, therefore, of opinion that there is still room 

 to doubt, in spite of this apparently conclusive experiment, whether the use 

 of seed from an infected crop is attended with much danger of conveying the 

 disease under the normal conditions of cultivation. It is clear, however, that 

 the disease can be conveyed by the seed and the exact conditions necessary to 

 enable this to occur must be further inquired into. 



The relative immunity of transplanted paddy. 



As already stated transplanted paddy ordinarily escapes ufra. The 

 explanation of this as regards the boro paddy has already been given, but 

 this explanation does not apply to transplanted aus and aman. 



Transplanted aus is chiefly found in high land in which the water is held 

 by embankments. The fields are fed by rain water or by the surface flow 

 from higher land. The general flood spill from the rivers does not reach these 

 levels at all during the growth of the crop, and after harvest, when the bunds 

 are not maintained, the transplanted aus fields are dry enough to walk through. 

 Thus, unlike the great bulk of the rice lands, fields that bear this class of aus 

 are dry for the greater part of the year. Furthermore, the stubble is very 

 scanty as the plants are cut near ground level. Thus, even if the transplanted 

 aus were to get infected, few worms would be left behind in the stubble after 

 harvest, since they are very rarely found near the base of the plant, and these 

 would have to survive a period of drying on the soil of some nine months 

 before a new crop became available. This they might conceivably do if they 

 remained in protected positions within the sheaths and glumes of the stubble, 

 but such well-protected parts are mostly removed during harvest and any 

 worms left behind would be likely to be set free into the soil by the heavy 

 rainfall after harvest. Thus the conditions would ultimately be the same 

 as have been proved by Experiments VII and X to free infected plots from 

 the disease. 



The same arguments apply to the bulk of the transplanted aman, except 

 that the period between harvest and transplanting the new crop is less by 



