NEMATODE GALLWORM ON POTATOES, ETC., IN NEVADA. 13 
SUMMARY. 
During the seasons of 1910 and 1911 there has been a serious 
infestation of certain potato fields in Nevada caused by a nematode 
gallworm known as Heterodera radicicola. This has resulted in hin- 
dering the marketing of Nevada potatoes in California, where the 
crop has been sold heretofore. 
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Fic. 17—Parsnip at- i Ke 1 
tacked and deformed i x 
Fic. 16.—Radish show- by the gallworm. This BX 
ing root enlargements disease attacks the qo 
caused by the gall- roots of hundreds of i 
worm. Care should other kinds of plants. Fic. 18.—Roots of salsify, 
If such roots are used showing enlargements 
be taken not to con- 
fuse these enlarge- 
ments with those of 
clubroot, a disease oc- 
curring on cabbage, 
turnips, and related 
plants. (After J. C. 
Neal.) 
for food the _ refuse 
should be cooked or 
destroyed. Such ma- 
terial can not be intro- 
duced into New South 
Wales and other pro- 
gressive States. (After 
caused by the gallworm. A 
number of foreign countries 
have legislated against the 
introduction of plants and 
farm produce infested with 
this disease. (After George 
F. Atkinson.) 
N.A. Cobb.) 
The parasite causing the disease is a very small unsegmented worm 
which invades the roots of many different plants, causing malforma- 
tions and often seriously hindering the growth of the plants. The 
nematode multiplies very rapidly under favorable conditions. The life 
cycle may be completed within a few weeks and each female may 
lay as many as 500 eggs. 
The nematode may be carried from place to place in the roots of 
living plants, in potatoes, on soil on the roots of nursery stock, or 
with potted plants. It may also be carried from one field to another 
in earth on farm implements or in irrigation water. Manure from 
yards where diseased roots or tubers have been fed may carry the 
[Cir, 91] 
