12 NEMATODE GALLWORM 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 be accomplished only 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 
sou is hight and subject to wind erosion. 
Fic. 14.—Roots of sugar cane, show- 
ing enlargements caused by the 
gallworm. This worm is common 
and destructive in the Tropics. 
Many plants of the grassfamilyre- Fic. 15.—Roots of tomato, showing enlargements caused by the 
sist the disease. (After N. A. gallworm. Tomatoes sometimes sufier severely from this 
Cobb.) disease. (After George F. Atkinson.) 
CROPS SUGGESTED FOR INFESTED AREAS. 
Probably the best means of combating the nematode is by plant- 
ing crops which are not subject to its attacks. Such crops as corn, 
sorghum, wheat, rye, oats, and barley 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 planted on fields known to be infested. 
[Cir. 91] 
