FLORIDA STATE HORTICULTURAL SOCIETY. 
27 
they are hatched. A larvae seeks out the 
root tip and bores into it by means of 
its spear, taking its place near the center, 
parallel to the axis of the root, with the 
anterior end directed away from the root 
tip. The necessary nourishment is sucked 
out of the surrounding tissue through 
the spear which is hollow. Growth is 
rapid now, and soon the nematode begins 
to increase in thickness more rapidly than 
in length. The tip of the root continues 
to grow. The tissue about the nematode 
owing to some stimulus, due to its pres¬ 
ence increases rapidly in amount, forming 
a knot of soft watery cells. If but one 
nematode has entered, the knot remains 
small, usually, but often the infections 
are not single and several to many nema¬ 
todes come to lie close together or at short 
intervals causing a large knot or a succes¬ 
sion of smaller one to be formed. The 
nematode’s increase in thickness contin¬ 
ues until it is flask-shaped. At this stage 
the male and female begin to become dif¬ 
ferentiated in shape; the former perform¬ 
ing a moult and again becoming a slenaer 
creature about 1-25 inch long and 1-500 
inch thick. The female, on the other 
hand, continues to enlarge until she is as 
thick as long, and only at the anterior 
end shows any worm-like portion. At 
this stage the egg laying begins, and con¬ 
tinues until 400-500 eggs have been laid. 
As these hatch they must bore their way 
out of the root tissue into the soil, and 
seek other roots or they simply find con¬ 
genial places to develop in the same knot 
so that in one large knot can be found 
nematodes of all stages of development. 
The time required for the development 
from the egg to the mature egg-laying 
individual depends to a great extent upon 
the temperature and upon the plant affect¬ 
ed, being more rapid in warm weather. 
It probably never is less than four weeks, 
and sometimes requires eight weeks. 
The injury to the plant is of two kinds, 
direct and indirect.- As direct injury may 
be considered that due to the reduction or 
stoppage of the passage from the roots 
of water and dissolved mineral food¬ 
stuffs, due to the tangling and interrup¬ 
tion of the water conducting vessels in 
the knotted roots, also the injury to the 
plant due to the diversion of food-stuffs 
to build up the tissue of the knot instead 
of building up the rest of the plant. 
Then direct injuries, although undoubt¬ 
edly harmful, rarely cause the death of 
the affected plants. The indirect injuries 
are due to the fact that the soft abnormal 
tissue of the knot is attacked by various 
organisms of both fungous and animal 
nature, causing decay to set in which may 
involve the whole root system and thereby 
kill the plant. Many fungi find easy en¬ 
trance in this way. So, for example, the 
fungus causing wilt of cotton attacks 
plants suffering with root-knot much 
more vigorously and destructively than 
those that are not so infested. 
Many plants are attacked so slightly 
that the injury is very slight or not even 
apparent. Such plants, however, owing 
to the large number of eggs laid b}^ a 
single worm, serve the purpose of keeping 
the soil well stocked with nematodes. 
I have been making a list of all plants 
on which I have seen root-knot or on 
which it has been reported to occur. This 
list now contains about 300 species of 
plants, including most of those commonly 
cultivated. Among those that may be 
seriously injured, may be mentioned the 
following: fig, peach, European grape, 
roselle, banana, pawpaw, tomato, egg¬ 
plant, rose, carnation, tuberose, violet, 
jasmine, cowpea, soy-bean, cotton, and 
