I lllllll 111 
STEM NEMATODE ON WILD HOSTS. 7 
occasionally found growing entirely by itself, isolated by several feet 
from any others. Frequently such isolated plants were diseased as 
badly as those found in close association in thick beds. In one spot 
near Newport, Oreg., scattered diseased plants were found at the 
lower edge of a thick growth of salal (Gaultheria shatton) on the 
face of a perpendicular bluff. Similarly wdth Hypochaeris, a single 
diseased plant was found growing in a small pocket of soil at the 
edge of a jagged rock more than 4 feet distant from any other vege- 
tation. 
Nothing is known as to the chief agencies for the distribution of 
this disease among wild plants. Besides the gradual spread through 
runners or stolons, which occurs with strawberries, animals, birds, 
wind, water, etc., readily occur to the mind as possible agencies of 
dissemination. But even with these and other means active in help- 
ing to spread the pest, it seems entirely unlikely that it could have 
reached its present distribution during the time that it has been 
known to occur on the cultivated plants in the same region. In fact, 
as previously mentioned, the evidence seems to point to the conclu- 
sion that the pest has been present on the wild plants for many years 
and that it is now passing, in some localities at least, from the wild 
to cultivated strawberries. 
It is just as possible to conceive of the nematode as a native of 
that region as to conceive of the many native plants as having 
evolved there. It is equally plausible, however, to recognize the pos- 
sibility of the pest having been introduced perhaps a hundred years 
ago when ships sailed from northwestern ports laden with lumber 
and other products and came back sometimes with dirt ballast from 
European ports. 
The interesting fact must be recorded here that Hypochaeris 
tadicata is, according to Piper and Beattie (#), a weed that is not 
native to that section. It is said to have been introduced from 
Europe. This fact naturally adds considerably to the interest of the 
problem, particularly in connection with speculation as to the origin 
of the disease and how it has become so widespread. 
INOCULATION EXPERIMENTS. 
Inoculations were made as a rule by the rough but effective 
method of simply breaking up diseased plants containing living 
nematode material — eggs, larva?, and adults — and stirring them into 
the soil. Careful observations showed that this releases the organ- 
isms into the soil, from which they enter immediately any host plant 
they may be able to infest. 
Shortly after the occurrence of the disease on cultivated straw- 
berries in the Northwest became known in 1919. diseased specimens 
sent to Washington, D. C, were used to inoculate Fragaria vesca y 
F. virgimca, F. platypetala, and F. chMoensis, all of which were 
successfully infected. No significance was attached to this at the 
time, however, except in possible relation to future studies on re- 
sistance. It was not until two years later that F. chiloensis was 
found naturally infested. 
Inoculations of red-clover seedlings were made at Corvallis, Oreg.. 
with the wild-strawberry material, and typical infections wen 1 
cured. In Plate I, Z>, are shown typical diseased clover seedlings 
