2G0 



the plants may bear desiccated worms in the lower parts, escapes 

 the injury to the ears and upper part of the stem that causes such 

 losses in the later crops, and is harvested before the break of the rains 

 would allow of further infestation. In the same way, the autumn 

 paddy does not become severely attacked until June (infestation 

 probably taking place in May), though worms must be present in 

 the water of the lower-lying tracts from the first flooding of the fields. 

 The winter paddy (the main crop) is doubtless attacked at the same 

 time, but the attack escapes notice as the crop is still very immature. 

 That the damage to the winter crop is so much greater than to the 

 autumn one is probably due to reproduction only being possible after 

 the rains break, that is, shortly before the autumn crop is harvested, 

 while it continues for several months during the maturing of the 

 winter one. 



T. angustus can only feed on certain parts of the plant ; these 

 include the young ear, the peduncle, the part of the stem just above 

 the upper nodes, the leaf-sheath and the young leaf-blades inrolled 

 towards the centre of the bud above the growing point. It is not 

 until the ear is forming and the worms collect at its base and above 

 the top nodes of the stem that the strain becomes more than the plant 

 can meet. It is quite possible to keep even severely infested young 

 plants growing, but often impossible to get them to bear mature ears. 



Many inoculation experiments carried out at Pusa are described. 

 These indicate that the disease only develops during the monsoon, 

 unless the plants are covered so that they grow in a saturated atmos- 

 phere. The question of soil and seed infestation are discussed ; it 

 is considered that infested matter does not remain in the soil if all 

 the stubble be removed ; infestation may under certain conditions 

 be carried by the seed, though this is unusual. The relative immunity 

 of transplanted paddy is chiefly because transplantation is made 

 on to high ground that is dry during the greater part of the year. 

 There is as yet no indication that any variety of paddy is naturally 

 resistant to the attacks of this Nematode, though some varieties do 

 not give sufficient time between infestation and harvest to allow of 

 much multiplication of the worms, while other early maturing varieties 

 are well advanced before the disease usually begins. Unless there 

 exists a variety with such thickened or hardened outer cell-walls 

 that the mouth-parts of the worm cannot pierce them, it is unlikely 

 that immune varieties will be found. 



Suggestions for improvement in rice-growing include the intro- 

 duction of early maturing kinds, and the re- arrangement of the levels 

 of particular fields so that transplanted winter or spring crops can 

 be grown in place of long-stemmed winter ones. The growing of 

 jute in some classes of infested land has been advocated with the 

 idea that if the paddy crop could be replaced even for a year the 

 worms would die out. Another practice is to take first a crop of 

 jute and follow it by a crop of transplanted winter rice put in in 

 August. This cannot be done on the lowest land. The problem is 

 more an agricultural than a pathological one. It has been conclu- 

 sively proved that the destruction of the stubble of the winter rice 

 will alone effect a great improvement, while if this can be followed 

 by ploughing and keeping the field dry for two or three months the 

 worms can be completely destroyed. The methods must vary in 



