Journal of Nematology 21(2):242-246. 1989.
© The Society of Nematologists 1989.
Efficacy of Oxamyl Coated on Alfalfa Seed with a
Polymer Sticker in Pratylenchus and
Meloidogyne Infested Soils
J. L. TOWNSHEND l
Abstract: A polymer sticker was used as a coating in which oxamyl was applied to seeds of alfalfa
cultivar Saranac for the control ofPratylenchus penetrans and Meloidogyne hapla. The sticker, diluted
1:1 (sticker:water) to 1:5, delayed seedling emergence during the first 4 days after planting. By day
13, however, emergence from all sticker treatments was comparable to the control. Shoot growth
of seedlings at day 21 was less than that of the control only from seeds coated with a 1:1 dilution;
root growth and nodulation were not affected. Sticker-coated seeds absorbed 30-58% as much water
in 3.5 hours as was absorbed by uncoated seeds. Oxamyl concentrations of 40-160 mg/ml in a 1:5
sticker : water mixture had no adverse affect on seedling emergence, growth, and nodulation over
3 weeks. Oxamyl at 160 mg/ml was more effective against P. penetrans than 21/1. hapla. Growth of
alfalfa in P. penetrans-infested soil was greater than that of the control in each sampling for 11
weeks. The reduction of number of P. penetrans in soil and roots moderated slowly over 11 weeks
from 90% to 60%. Shoot and root growth of alfalfa from oxamyl-coated seed in M. hapla-infested
soil were greater than those of the control for 7 and 11 weeks, respectively. The reduction in the
number ofM. hapla in the soil and roots changed from 80% at 7 weeks to 15% at 11 weeks.
Key words: alfalfa, lesion nematode, Medicago sativa, Meloidogyne hapla, oxamyl, Pratylenchus p~ne-
trans, root-knot nematode, seed treatment, sticker.
In earlier studies seeds of alfalfa (Medi-
cago sativa L.) were soaked in an aqueous
solution of oxamyl for 17 hours (5). With
such a long soaking period, the integument
on some seeds ruptured. In subsequent
studies oxamyl was coated on alfalfa seeds
with stickers. Acacia and gelatin stickers
inactivated oxamyl, rendering it ineffec-
tive against nematodes (Townshend, un-
publ.). Pelleting oxamyl on alfalfa seeds
with clay also inactivated the nematicide.
A 2% cellulose solution (6) and a polymer
sticker were effective coating agents for
oxamyl. This paper reports the optimum
concentrations of a polymer sticker and ox-
amyl and the degree and duration of con-
trol of Pratylenchus penetrans Cobb and Me-
loidogyne hapla Chitwood with oxamyl-
MATERIALS AND METHODS
A polymer sticker was used as the coat-
ing agent for the application of oxamyl to
Received for publication 19 August 1988.
1 Research Station, Agriculture Canada, Vineland Station,
Ontario, Canada L0R 2E0.
The author thanks Mr. T. S. Baillie, General Manager,
Canadian Seed Coaters Limited, P.O. Box 219, Brampton,
Ontario, Canada L6V 2L2. for providing the polymer sticker
for this study. The chemical composition of the sticker is
the seed of alfalfa cultivar Saranac. Seeds
were coated as described in detail earlier
(6). Briefly, 3 g of seed were placed in a
tumbler and 0.5 ml sticker or sticker plus
oxamyl was added drop by drop with a pi-
pet. The seeds were then dried in a
screened trough using warm air from a
built-in hair dryer. The procedure was re-
peated two more times, adding 0.5 ml of
material each time.
A series of five experiments were con-
ducted, and all data were subjected to anal-
ysis of variance.
Influence of the polymer sticker on growth:
In a preliminary experiment with the poly-
mer sticker and oxamyl, there was an in-
dication that the sticker, the oxamyl, or
both adversely affected alfalfa. Conse-
quently, the sticker was diluted 1:1, 1:2,
1:3, 1:4, and 1:5 (sticker:water) and ap-
plied to the seed without oxamyl. A Vine-
land silt loam (VSL) (61% sand, 28% silt,
11% clay) was steam sterilized for 1 hour
and cooled for 12 hours before use. Sixty
styrofoam pots (11.5 cm d x 7.5 cm high)
were each filled with 425 g soil, and 20
indentions were made in the soil surface
with a multipoint dibble. A single seed was
inserted into each site. Seeds were dusted
with Rhizobium meliloti Rangeard and cov-
Oxamyl Sticker Alfalfa Seed Coating: Townshend 243
ered with 30 ml soil. The six treatments,
five concentrations of sticker and a control,
were replicated 10 times. The experiment
was arranged in a randomized block design
in a growth room with temperatures of 14
C at night and 17 C during the day at a
light intensity of 11,000 lux for 16 hours.
Seedling counts were made every 2 days
from day 4 to day 13. The experiment was
concluded at 3 weeks, and shoot and root
weights and numbers of nodules deter-
Absorption of water by coated seeds: Four
subsamples of 20 seeds were selected from
each of the five lots of alfalfa seeds coated
with dilutions of sticker, 1 : 1 to 1:5 (sticker :
water), and from one lot of uncoated seeds.
Each of the 24 lots of seed were weighed
and placed in shallow plastic dishes (44 mm
× 44 ram). Water (2.5 ml) was pipetted into
each dish and floating seeds were sub-
merged. The seeds were soaked for 3.5
hours after which the water in each dish
was removed with a suction pipe~ ~nd each
lot of seed was weighed. The amount of
water absorbed was calculated as milli-
grams per 20 seeds.
Influence of oxamyl on growth: Three con-
centrations ofoxamyl (40, 80, and 160 mg/
ml) were prepared with the sticker in a 1:5
(sticker : water) ratio. Three coats of these
solutions were applied to 3-g lots of alfalfa
seed as described (6). Two controls, un-
treated seed and seed with sticker only, and
seed with the three concentrations of ox-
amyl were planted in steamed soil. Each
treatment was replicated 10 times. Treat-
ments were arranged in a randomized block
design in a growth room with temperatures
of 13 C night and 17 C day at 11,000 lux
of light. Seedling counts were made on days
4, 8, and 13, and shoot and root weights
and number of nodules were determined
at week 3.
Control of Pratylenchus penetrans: Eighty
styrofoam pots (11.5 cm d x 14 cm high)
were filled with a VSL soil infested with P.
penetrans (five/g soil) from a greenhouse
ground bed culture. Forty pots were sown
with untreated alfalfa seed and forty with
alfalfa seed coated with 160 mg oxamyl/
ml sticker (1:5 sticker:water) as described
in the first and second experiments. The
seed rows were dusted with Rhizobium mel-
iloti and covered with 30 ml infested soil.
The pots were arranged in a randomized
block design in a growth room with a 16-
hour day at 17 C with 11,000 lux of light
and 13 C at night. Eight replicates of each
treatment were harvested at 3, 5, 7, 9, and
11 weeks, and shoot and root weights and
number of nodules were determined. P.
penetrans were extracted from 50-g soil
samples for 1 week and from the roots for
2 weeks by the pan method (4).
Control ofMeloidogyne hapla: The control
experiment was repeated with a VSL soil
infested with M. hapla (six J2/g soil) from
a greenhouse culture. In addition to the
other data obtained root-knot galls were
counted at each harvest.
Influence of the polymer sticker on growth:
The sticker applied to alfalfa seed delayed
seedling emergence only during the first
11 days after planting (Table 1). Seedling
emergence was delayed by all sticker di-
lutions in the first 4 days; by dilutions 1:3
to 1:1 for 6 days; and by dilution 1:1
through 11 days. On day 13 after planting
seedling stands of the five treatments were
comparable to the control (Table 1).
Shoot weight of seedlings from treated
seed at 21 days was less (P -< 0.10) than
that of the control only when seed had been
coated with sticker at a dilution of 1:1 (Ta-
ble 1). Neither root weight nor nodulation
were affected by the sticker applied to the
seed (Table 1).
Absorption of water by coated seeds: In 3.5
hours, 20 uncoated alfalfa seeds absorbed
25.1 mg water; seeds coated with 1:5 di-
lution sticker, 14.6 rag; 1:4 dilution sticker,
13.1 rag; 1:3 dilution sticker, 11.3 mg; 1:2
dilution sticker, 7.7 mg; and 1:1 dilution
sticker, 7.7 mg (LSD5% = 5.0). Uncoated
seeds were visibly larger than the coated
seeds, particularly those coated with 1:1
Influence of oxamyl on plant growth: The
three concentrations of oxamyl used to coat
244 Journal of Nematology, Volume 21, No. 2, April 1989
TABL~ 1. Effect of five concentrations of a polymer sticker coating on alfalfa seed on seedling stand,
growth, and nodulation of alfalfa.
Sticker : water
pot 4 days 6 days 11 days 13 days
Values are means of 10 replications.
t Shoot and root weights are fresh weights in grams per pot
alfalfa seed had no adverse effects on
growth over 3 weeks. Seedling stands at
day 4 ranged from 13.8 to 15.0 seedlings
per pot and at day 13 from 16.4 to 17.1
seedlings per pot. Shoot weights at harvest
ranged only from 2.3 to 2.4 g per pot and
root weights from 1.3 to 1.4 g per pot.
Number of nodules varied from 88 to 112
per pot of roots.
Control of Pratylenchus penetrans: Shoot
weight of alfalfa seedlings from seed treat-
ed with oxamyl + sticker was consistently
greater than that of the control for 11
weeks in P. penetrans-infested soil (Table
at day 21.
2). Shoot weight increase reached a peak
of 30% over the control at week 7 and was
still 12% greater at week 11. Root weight
of seedlings from oxamyl-treated seed was
37% greater than that of the control at
week 7 and was still 15% greater in week
11. The number of nodules on the roots
of alfalfa seedlings from oxamyl-treated
seed was greater than on the control. The
greatest increase in nodulation (159%) oc-
curred in the first 3 weeks and then de-
clined to a low of 7% by week 7.
The numbers ofP. penetrans in the roots
of alfalfa seedlings that grew from oxamyl
TABLE 2. Growth of alfalfa and numbers of nematodes in Pratylenchus penetrans-infested soil planted with
seed treated with oxamyl (160 mg/ml sticker) in a polymer sticker or with sticker alone (1:5 sticker:water).
planting Treatment Shoot weightt
Root weightt Nodules/pot Soil Roots
Values are means of eight replications.
1" Shoot and root weights are fresh weights in grams per pot.
Oxamyl Sticker Alfalfa Seed Coating: Townshend 245
TABLE 3. Growth of alfalfa and numbers of galls and juvenile nematodes in Meloidogyne hapla infested soil
planted with seed treated with oxamyl (160 mg/ml sticker) in a polymer sticker or with sticker alone (1:5
sticker : water).
weight'i" Nodules/pot Treatment Galls Soil Roots
Values are means of eight replicates.
t Shoot and root weights are fresh weights in grams per pot.
sticker-coated seeds was approximately
12% of the numbers in the roots of the
control at week 3 (Table 2). Over the next
8 weeks the numbers ofP. penetrans in roots
of seedlings from treated seeds increased
to 38% as many as in the controls. There
were 8% as many P. penetrans in soil in
which oxamyl-treated seedling were grow-
ing as in the control soil at week 5 and 20%
as many at week 11.
Control of Meloidogyne hapla: Shoot and
root weights of alfalfa seedlings from ox-
amyl-coated seeds exceeded that of the
control seedlings at 7 and 11 weeks, re-
spectively (Table 3). Shoot weight of seed-
lings from treated seeds was 141% of the
control at week 3 and 123% at week 7.
Root weights of seedlings from treated
seeds were 210% of the control at week 5
and 117% at week 11. The number of nod-
ules on alfalfa seedling roots from oxamyl-
coated seeds was 132% of the control at
week 3 but not significantly different there-
There were only 30% as many root-knot
galls on the roots of alfalfa seedlings from
oxamyl-coated seeds as on the roots of the
controls at week 3 but the number in-
creased to 59% as many at week 11 (Table
3). There were 19% as many juveniles in
the soil around seedlings from treated seeds
at week 7, compared with the control soil,
but at week 11 there were 65% as many
(Table 3). At week 7, 25% as many juve-
niles were extracted from the roots of al-
falfa seedlings from oxamyl-coated seeds
as from the roots of the control; by week
11 the difference was 85% as many.
A sticker such as the polymer used in
this study may have to be diluted to allow
greater absorption of water and an ac-
ceptable rate of seed germination. Coating
alfalfa seed with this sticker diluted 1:1 to
1:3 delayed seedling emergence either be-
cause of inhibition of water absorption or
a direct seedling inhibition. At week 3,
however, the effect had disappeared re-
gardless of the concentration of sticker on
the seed. This commercial sticker appar-
ently should be diluted 1:5 for coating al-
falfa seeds. Other types of stickers may re-
quire a different dilution.
246 Journal of Nematology, Volume 21, No. 2, April 1989
The use of stickers on seeds without the
addition of pesticides could be advanta-
geous in dryland farming. Sticker-coated
seeds could delay germination until ade-
quate moisture is available, not only for
germination but also for seedling estab-
lishment. With uncoated seeds rainfall may
be adequate for germination but inade-
quate for seedling establishment, resulting
in the need for reseeding.
Alfalfa seeds were tolerant of oxamyl
even when coated with high concentra-
tions. The concentration of 160 mg oxa-
myl/ml, was more than three times that
used in an earlier study (6), yet seedling
emergence was not delayed nor were
growth and nodulation adversely affected
3 weeks after planting. In studies with
wheat, rye, oats, and rye grass, oxamyl ap-
plied to seed in solutions of 50 mg/ml af-
fected germination and plant height (1-3).
Oxamyl was also toxic to carrot when ap-
plied to seed in a solution of 40 mg/ml
(Townshend, unpubl.) and to corn when
applied to seed in a solution of 8 mg/ml
(1). The hard cotyledons and integument
of alfalfa seed may provide greater pro-
tection to the embryo than does soft seed
such as tomato. The epidermis that pro-
tects the embryo of corn may provide even
less protection against oxamyl than the in-
tegument and cotyledons of alfalfa. Alfalfa
seeds are very small and smaller quantities
of oxamyl may adhere even though high
concentrations of oxamyl are used for coat-
ing, whereas larger quantities of oxamyl
may adhere to larger seed such as corn
even though low concentrations were used
for seed treatment. In an earlier study (5)
the duration of the application of oxamyl
was found to affect toxicity; oxamyl was
toxic at 16 mg/ml when alfalfa seeds were
soaked for 17 hours in water. The integ-
ument on many of the seeds had ruptured
after 17 hours, probably exposing the em-
bryo to the oxamyl solution.
Oxamyl coated on seed was more effec-
tive as a control for P. penetrans than for
M. hapla. The reduction in the numbers of
P. penetrans in soil and roots was greater
and lasted longer. The more effective con-
trol of P. penetrans was also reflected in
increased shoot growth for 11 weeks; shoot
growth ofM. hapla-inoculated seedlings in-
creased for only 7 weeks.
This study has shown that oxamyl-coat-
ed seed provides effective control of P. pen-
etrans and M. hapla on alfalfa and assures
better plant growth for a few weeks. Coat-
ing alfalfa seed is a precise means of ap-
plying oxamyl in the vicinity of alfalfa seed-
lings, whereas the application of granular
oxamyl or aldicarb to the soil at planting
is much less precise. Alfalfa seed are gen-
erally spread on the soil surface with a ro-
tary seeder and then incorporated into the
soil with a cultivator. Oxamyl and aldicarb
granules are coarser than alfalfa seed. Con-
sequently the rotary seeder must be read-
justed before applying granular nemati-
cides to the soil surface as a separate
application before incorporation into the
soil. This is inconvenient, time consuming,
and an added expense. There is sophisti-
cated equipment with which seed and gran-
ular nematicides can be spread on the soil
surface in one application, but this, too, is
1. Fulop, G.J. 1987. The identification, distri-
bution and persistence of oxamyl and its degradation
products in planted corn seed, seedling root and soil
from oxamyl-treated corn seeds. M.Sc. Thesis, Brock
University, St. Catharines, Ontario, Canada.
2. Hoveland, C. S., R. Rodriguez-Kfibana, and R.
L. Haaland. 1977. Phytotoxicity and efficacy of ne-
maticide seed treatment on wheat, rye, oats, and rye-
grass. Agronomy Journal 69:837-839.
3. Rodriguez-Kfibana, R., C. S. Hoveland, and R.
L. Haaland. 1977. Evaluation of a seed-treatment
method with acetone for delivering systemic nema-
ticides with wheat and rye. Journal of Nematology 9:
4. Townshend, J. L. 1963. A modification and
evaluation of the apparatus for the Oostenbrink di-
rect cottonwool filter extraction method. Nemato-
5. Townshend, J. L., and J. W. Potter. 1979. In-
hibiting infection of alfalfa seedlings by Pratylenchus
penetrans by treating seed with oxamyl. Canadian
Journal of Plant Science 59:519-520.
6. Townshend, J. L., and M. Chiba. 1987. Control
of Pratylenchus penetrans and Meloidogyne hapla and
yield response of alfalfa due to oxamyl seed treat-
ments. Journal of Nematology 19:454-458.