12 NEMATODE GALLWOEM ON POTATOES, ETC., IN NEVADA. 



frames by methods of sterilization with steam or chemicals; but such 

 methods are too expensive for field application. Where the gallworm 

 occurs in fields, its subjugation can bo accomplished onl}' by slower 

 methods. In some cases it may be possible to flood land with irriga- 

 tion water and keep it submerged for a period of several months, and 

 thus destroy the living nematodes and the eggs; but in view of the 

 fact that nematodes are usually more abundant on light sandy soils 

 than on heavy soils such protracted flooding is not often practicable. 



It may also be possible in some cases to keep 

 the infested field in clean fallow long enough 

 to starve out all the nematodes: but this is 

 hardly practicable in any region where the 

 soil is light and subject to wdnd erosion. 



Fig. 14. — Roots of sugar cane, show- 

 ing enlargements caused by the 

 gallwoiTn. This worm is common 

 and destructive in the Tropics. 

 Many plants of the grass family re- 

 sist the disease. (After N. A. 

 Cobb.) 



Fig. 15.— Roots of tomato, showing enlargements caused by the 

 gallworm. Tomatoes sometimes suffer severely from this 

 disease. (After George F. Atkinson.) 



CROPS SUGGESTED FOR INFESTED AREAS. 



Probably the best means of combating the nematock^ is b}- plant- 

 ing crops which are not subject to its attacks. Such crops as corn, 

 sorghum, wheat, rye, oats, and barlo}^ are among the most promising 

 for this purpose. Corn and sorghum are particularly desirable, be- 

 cause they permit clean tillage, and thus all weeds and other plants 

 on which the nematodes might live may be kept out. It should be 

 particularly noted that the sugar beet is susceptible to the nematode 

 and should not be ])lanted on fields known to be infested. 



fCir. !)n 



