8 NEMATODE GALLWORM ON POTATOES, ETC., IN NEVADA. 
clean and healthy seed from fields where a critical inspection shows 
that the disease has not been present. 
All culled potatoes from the field should be examined, for even 
when disease is present the bulk of the crop may be unaffected. 
The gallworm does not occur in the potato-growing districts of the 
Northern States, particularly North Dakota, Minnesota, Wiscon- 
sin, and Maine. Seed obtained originally from these States and 
grown on fields that are free from the gallworm should be safe to 
use in planting other uninfested fields. Too much stress can not 
be laid upon the importance of securing for planting 
potatoes which are uninfected and in planting them 
on uninfested land. 
LOCALIZATION OF INFESTED AREAS. 
The practical problem which confronts the potato 
growers of Nevada is the location of all fields which are 
infested with this parasitic nematode. The present 
indications are that the nematode infestation is by no 
means general in irrigated land. The nematode has 
probably existed in some of the older irrigated lands 
of the State for many years, but there is much new 
gee eens ‘= land being put under irrigation in Nevada, which it 
gallworm. These seems probable is entirely free from thisworm. [If all 
aes are oanctY’ of the infested areas can be located by acritical inspec- 
atode disease. They tion, 1t will be possible to produce potatoes in large 
sity mires Bo quantities on uninfested land and devote the infested 
figure 4. (AfterN. land to crops which are resistant to the parasite. 
amass There are probably some fields in the State which 
have been devoted to potatoes during the last year or two on which 
the parasite does not occur, and from these uninfested fields seed might 
be secured. It would be much safer, however, to obtain seed from 
the Northern States, such as Minnesota, Wisconsin, or North Dakota, 
with which to plant new land, rather than to risk the infestation of 
the new land with local seed. But it will be impossible to proceed 
intelligently in combating the ravages of the gallworm until the 
infested areas have been located, so that the danger of infestation, not 
only by means of potatoes but In many other ways, can be fully 
ascertained. 
SUSCEPTIBILITY OF OTHER PLANTS. 
In view of the fact that the gallworm is parasitic on many plants 
other than potatoes, it is important not to foster the parasite by the 
culture of plants which are subject to its attacks. The following is 
a list of some of the plants which are readily and seriously attacked 
by the gallworm and which should never be grown on infested fields 
[Cir. 91] 
