phosphoramidethioate) has also been found 
to possess limited nematocidal properties, 
None of these chemicals are currently recom- 
mended for nematode control, 
With continued chemical synthesis and im- 
provement of application methods, the organic 
phosphates probably can be developed into 
highly effective chemicals for controlling 
nematodes on established plants, such as 
ornamentals, shade trees, bulbs, and forage 
and lawn grasses, 
ADVANCES IN NEMATOCIDE 
APPLICATION 
During the past 10 years great advances 
have been made in developing equipment and 
improving chemical formulations so that 
nematode control is now possible for most 
crop and soil conditions, Recent equipment and 
formulation advances have made _ possible 
chisel application of methyl bromide with 
tractor-drawn equipment (21, 22), resulting 
in a saving of time and labor, as well as in 
the amount of chemical used, New equipment 
and methods also have been developed for 
applying general soil disinfestants by in-the- 
row methods, These improved row-application 
techniques provide a sterile planting band, 
or zone, 10 to 14 inches wide in which 
nematodes, soil diseases, weeds, and insects 
are controlled, This type of high-level crop 
protection may be particularly useful in the 
production of truck crops, which are not of 
high enough value to justify conventional over- 
all application of general soil disinfestants, 
Furrow application of pesticides during the 
planting operation is becoming increasingly 
popular (3, 4), Savings in operational cost 
usually offset losses of effectiveness of pesti- 
cides applied in this manner, Nematodes, 
soil fungi, and insects have been controlled 
in experimental tests and farm demonstra- 
tions by furrow applications of combination 
mixtures of nematocides, fungicides, and in- 
secticides, Granular formulations, particu- 
larly of nematocides containing dibromo- 
chloropropane that can be mixed with 
fertilizers and applied in the furrow, have 
made control of nematodes practical on a 
55 
number of relatively low-value crops, such 
as cotton, peanuts, and some vegetables in 
several areas of the country, 
Recent investigations of nematologists in 
Arizona and California have shown that some 
nematocides can be applied in irrigation water 
(open ditch and flood irrigation) for such 
crops as cotton, sugarbeets, citrus, and 
vineyards (16, 18, 20), Nematode control by 
this method, though not recommended for 
all crops, usually equals that obtained by 
more conventional methods, Unproductive 
groves and vineyards that were in a state 
of decline caused by nematodes have been 
restored to high production by this inex- 
pensive method, 
RESEARCH NEEDS 
Such progress indicates the need of additional 
research to improve formulations, equipment, 
and application techniques in order to de- 
velop more efficient and economical applica- 
tion of nematocides, Especially needed are 
techniques to prevent rapid increase of nema- 
todes after chemical treatment, because 
nematocides seldom rid the soil of these 
pests, but only reduce their numbers below 
detection level, Proper soil management after 
use of nematocides may provide means to 
delay the return of damaging infestations and 
thereby reduce the frequency of nematocide 
use and lessen long-range crop losses caused 
by nematodes, In addition, basic studies are 
needed to determine the direct and indirect 
effects of nematocides on soil organisms and 
on the soil ecosystem, Such knowledge would 
provide the basis for manipulating soil and 
crop management practices for the best pos- 
sible growth of plants after use of nemato- 
cides, 
Emphasis should be placed onunderstanding 
and developing methods of counteracting the 
deleterious side effects of nematocide treat- 
ment of the soil, The most pronounced of 
these are nitrification lag, phosphorus de- 
ficiency, increased incidence of certain plant 
diseases, and stimulation of weed growth, 
Much information is needed on the exact 
method of nematocide movement in the soil 
