to seed as a preplant treatment, or to soil 
around plants, 
The prospect of finding nematode attractants 
is particularly interesting, because the avail- 
ability of an effective attractant would provide 
many possibilities of selecting nematocidal 
chemicals to combine with an attractant, When 
properly applied, such a mixture should entice 
and then kill the nematodes, Successful con- 
trol of nematodes by this method will require 
thorough soil incorporation of chemicals, be- 
cause most nematodes move only a few inches 
a month, necessitating placement of the chem- 
ical near the nematode by mechanical means, 
This is a difficult problem but not insur- 
mountable with adaptations of modern farming 
implements, 
Current basic studies are providing knowl- 
edge of the chemical nature of nematode 
resistance in plants, It is believed that basic 
discoveries will uncover chemical structures 
that may be synthesized and applied to plants 
so as to induce nematode resistance arti- 
ficially in plants, This intriguing approach to 
chemical control offers prospects of rendering 
common plant varieties resistant to nema- 
todes, and may eliminate the prolonged 
research required to develop nematode- 
resistant crop varieties by present breeding 
methods, 
Development of chemosterilants is another 
possible approach to controlling nematodes, 
Preliminary investigations by U.S, Agricul- 
tural Research Service nematologists and 
chemists (9) have shown that some highly 
reactive materials containing aziridine or 
triazine configurations, such as triethyl- 
enemelamine, simazine, and atrazine, and 
others, such as 5-flurorouracil, are effective 
in reducing nematode populations under con- 
trolled conditions in the laboratory, This 
work is of basic interest because it is the 
first demonstration of chemosterilant control 
of nematodes, These chemicals cause degen- 
erative changes in nematode gonad tissue, 
especially ovaries, and thereby control nema- 
todes indirectly by reducing the reproductive 
potential of the nematode population after 
each reproductive cycle, However, the de- 
velopment of effective, practical chemo- 
sterilant methods for nematode control will 
be difficult, because many of these materials 
create possible residues as wellas mammalian 
and plant toxicity problems, 
From the practical viewpoint, chemo- 
sterilants may not prove so effective against 
nematodes as against insects, The so-called 
sterile male technique, used so successfully 
against insects, may be of little or no value 
against nematodes, because males are not 
required for reproduction of many nematode 
species, Also, much of this method's success 
in insect control depends on a high rate of 
insect mobility, which allows treated indi- 
viduals to come in contact with individuals 
from the natural population; however, as we 
noted, nematodes move only several inches 
per month, precluding frequent contact of 
sterile and normal individuals, whichis needed 
for effective control, 
These are but a few of the great advances 
and problems in the chemical control of 
plant-parasitic nematodes, Techniques have 
been perfected, or are in the process of de- 
velopment, for control of many nematode 
types under a wide range of soil, crop, and 
cultural conditions, Even greater progress can 
be expected in the future as new nematocides, 
disinfestants, and other types of chemicals 
become available, 
LITERATURE CITED 
(1) Apt, Walter J,, H, M, Austenson, and Wilbur D, 
Courtney, 1960, Use of herbicides to break 
the life cycle of the bentgrass nematode, 
Anguina agrostis (Steinbuck 1799) Filipjev 1936, 
U.S. Agr. Res, Serv, Plant Dis, Rptr, 44: 
524-525, 
(2) Bell, A, A., and L, R, Krusberg, 1964, Occur- 
rence and control of a nematode of the genus 
Hypsoperine on Zoysia and Bermuda grasses 
in Maryland, U.S, Agr, Res, Serv, Plant Dis, 
Rptr, 48: 721, 
(3) Birchfield, W., and J, A, Pinckard, 1964, New 
combinations of nematocides for control of 
reniform nematode on cotton, Phytopathology 
54: 393-394, 
(4) Bird, L. S, 1963, In-covering soil fungicides, 
nematocides and insecticides for disease con- 
trol in cotton, Phytopathology 53: 622, 
