28 THE RICE WORM (tYLENCHUS ANGUSTUS) AND ITS CONTROL 



infection and harvest to allow of much multiplication of the worms. The 

 late dighas are liable to damage, as bas been found in the case of the kind 

 known as aghani dighain Backergunge. In the Feni Subdivision of Noakball, 

 an early maturing, long-stemmed variety called haroli, which ripens early in 

 October, is grown in land where the water is liable to subside early. This 

 kind suffers les^ from ufra than any of the other long-stemmed amans of the 

 district, not because it is resistant but merely because the crop is well advanced 

 when the disease usuaUy begins. So also the boro paddies escape not because 

 they are immune but because they grow at a season when the air is too dry 

 to allow the worm to migrate ; and the transplanted aus and aman varieties 

 because they have little stubble after harvest and their fields are dry for 

 much of the year. In every case that has been examined hitherto the reputed 

 resistance of a particular variety or class has failed to stand closer test. Thus 

 there is a variety of broadcasted aman called khama, much grown in Dacca 

 District, which was said not to get the disease. Exposed to artificial inocu- 

 lation it proved as susceptible as any other. It is usually grown on the sloping 

 side3 of the paddy bils, where early cultivation is possible after harvest, and it 

 has been found that fields intended for khama paddy are usually already 

 broken up and their stubble buried at the end of December or early in January. 

 The straw is not very long, and the amount of stubble is decidedly less than 

 in the kinds grown in the bottom of the bils. After ploughing, it decomposes 

 quickly enough to expose the worms to a period of life in relatively dry soil 

 which seems to be too long to enable them to survive until the following crop. 

 Aus paddy is reputed to be immune in Dacca District, but the immunity is 

 only apparent and is due to aus being grown on higher land in this area than 

 in the more recent parts of the dolta. Aus is often attacked in Noakhali and 

 Backergunge. Even the transplanted amans, which escape in practically 

 all parbs of the infected area, have been reported, as mentioned in the last 

 section, to take the disease sometimes when grown in relatively low land, and 

 they are readily attacked if artificially inoculated. 



Indeed it is scarcely reasonable to expect any such natural immunity to 

 ufra, amongst varieties of paddy, as occurs so usefully amongst plants subject 

 to fungal diseases. The rice worm is a coarse parasite as compared with most 

 fungi. It never enters into intimate relations with the life of the host plant 

 as so many fungi do, and instead of having to rely on enzymes to dissolve for 

 itself a passage into the tissues (enzymes being bodies notoriously susceptible 

 to alterations in the composition of the medium in which they work), the rice 

 worm bores a hole in the cell wall mechanically with its spear. Unless there 

 exist paddies with such thickened or hardened outer cell walls that the 



