Title: Nematode and corky ringspot control in potatoes using oxamyl in Northeast Florida
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 Material Information
Title: Nematode and corky ringspot control in potatoes using oxamyl in Northeast Florida
Physical Description: Book
Creator: Weingartner, David Peter,
Publisher: Agricultural Research Center, University of Florida
Place of Publication: Hastings, Fla.
Publication Date: 1981
Copyright Date: 1981
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Bibliographic ID: UF00076382
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: 145585620 - OCLC

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SHUM IJRA


AGRICULTURAL RESEARCH CENTER APR 20 198,
4\ Hastings, Florida
FIF.A.S.
Hastings ARC Research Report PR1981-5 Ap Off1

NEMATODE AND CORKY RINGSPOT CONTROL IN POTATOES
USING OXAMYL IIN NORTHEAST FLORIDA
D. P. Weingartner, Assoc. Plant Pathologist
J. R. Shumaker, Assoc. Horticulturist
G. C. Smart, Jr., Nematologist


Introduction

During the past several seasons, we have done considerable research with
field applications of oxanyl 2L (Vydate). Oxamyl is an interesting chemical
for several reasons. First, it is effective both as an insecticide and nema-
ticide. Depending upon the crop, the compound is labeled for control of
Colorado potato beetle, aphids, flea beetles, leaf hoppers, several leaf
miners and mites, scales, white fly, carrot weevil, thrips, and mealy bugs as
well as root-knot, pin, sting, lesion, reniform, burrowing and ring nematodes.
Secondly, although oxamyl is highly toxic, it breaks down rapidly having a
half life in the field of only 10-14 days. Last, oxamyl is systemic and when
the chemical is applied to foliage part is translocated to the plant roots,
thereby providing protection against nematodes, and in northeast Florida
* (NEF), corky ringspot disease (CRS) of potatoes.

Preliminary observations made during 1971-74 indicated that foliar appli-
cations of oxamyl would reduce incidence of CRS providing that applications
were precisely timed in relation to crop development. Several experiments
designed to determine the proper timing of foliar applications of oxamyl for
controlling nematodes and CRS were performed during 1975-80. Two of these are
discussed in this report.


Methods

1979 Experiment

The primary objective was to study effect of timing and dosage of foliar
and soil applications on incidence of CRS. The test was performed in a bed
known to have a high incidence of CRS. Since soil fumigation fails to control
CRS in NEF, the entire bed was fumigated with 1,3D (Telone II at 6.0 gallons/
acre in-the-ro) to minimize the effects of other nematodes on yield and tuber
quality. Based on previous experimental data oxamyl dosages and schedules of
application were selected to delineate the most effective combinations.
Oxainyl foliar applications were made in 100 gallons of water/acre as indicated
in Tables 1-A, B, and C. Hufilr-17 (7.0 oz) was used as a spray adjuvant.

1980 Experiment

Application dosages and schedules were selected using data from the 1979
experiment. In 1980, oxamyl applications were made in all combinations to
plots treated with 1,3), aldicarb (3.0 lb ai/acre), 1,3D + aldicarb, and a
nontreated control.










Observations

As summarized in Table 1, parts A, B, and C the percentage of tubers with
CRS was reduced in plots treated with aldicarb and those sprayed with various
combinations of oxamyl. Incidence of CRS was lowest when 5.0 lb ai oxamyl was
applied by 45 days after planting. No significant differences in yield were
observed in 1979.

Similar observations were made in 1980 (Table 2); however, in contrast to
1979, 5.0 lb ai applied by 60 days after planting was also effective. Oxamyl
applications affected yields in 1980 (Table 4). When compared to the control,
a significant increase in yield of US Size A tubers was observed following the
3+1+1 and 0+2+2+1 oxamyl treatments. At harvest population densities of tri-
chodorid (Table 3) and sting nematodes (Table 5), but not those of root-knot
nematodes (Table 6) were reduced following foliar applications of oxamyl. Ex-
ternal tuber quality defects were significantly reduced following oxamyl
applications (Table 7).


Discussion

Soil fumigation fails to control CRS in NEF because trichodorid nematodes,
the vectors of tobacco rattle virus, migrate from deeper nontreated soil into
the fumigated soil after the chemical has dissipated. The nematode migration
occurs within 35-45 days after planting. At plant applications of nematicides
such as aldicarb provide effective control of CRS because these chemicals
remain active when the nematodes are transmitting the virus. Similarly,
scheduling oxamyl applications so that 5.0 lb ai oxamyl have been applied
during the same time period effectively controls CRS. However, maximum yield
response associated with the control of other nematodes tends to occur when
treatments are extended closer to harvest.


Grower Summary

1. Nematode control and increases in yield have been observed following
foliar applications of oxamyl 2L.

2. Incidence of corky ringspot has been observed when 5.0 lb ai Vydate
have been applied by 45 days after planting.

3. Improvements in external tuber quality similar to those observed
with other nonvolatile nematicides have been observed following foliar appli-
cations of oxamyl.

4. Vydate 2L is labeled for nematode and insect control on Irish pota-
toes, however, does not currently have a use permit for CRS.


USE VYDATE 2L AND ALL PESTICIDES ONLY IN STRICT ACCORDANCE WITH LABEL INSTRUC-
TIONS.









Table 1. Percentage of tubers with corky ringspot, yield of US Size A
tubers, and trichodorid nematode population densities following
different application schedules and dosages of oxamyl 2L (Vydate).
1979 Oxamyl Experiment.1.

Part A. Comparison of different combinations of 1.0 lb ai/acre foliar
applications.
Tubers Yield Trichodorids/100 cm3
Oxamyl application with US Size A soil
schedule and dosage CRS tubers midseason harvest
A B C D E F / % cwt/acre


37.8b-e
37.8b-e
35.4b-e
49.3d-f
76.6f
60.0ef
61.5ef
65.6ef
74.3f


200
228
218
229
230
214
235
199
242


44a-d
46b-d
41a-d
36a-d
30a-d
28a-c
45a-d
18a-c
68d


26a
52ab
41ab
70b-d
103d
58a-c
47ab
31a
96cd


Part B. Comparison of different combinations
applications with no at plant


37.8b-e
37.6b-e
47.3c-e
24.8a-d
37.5b-e
57.3ef
74.3f


216
218
179
206
226
212
242


of 5.0 lb ai/acre foliar
application.


37a-d
37a-d
34a-d
34a-d
38a-d
52cd
68d


47ab
37ab
60a-c
59a-c
38ab
49ab
96cd


Part C. Comparison of 5.0 lb ai/acre rates applied as different com-
binations of foliar and at plant applications.


6.5a
20.5a-c
11.6ab
7.5a
74.3f


216
214
213
205
242


23a-c
7a
8a
12ab
68d


22a
28a
24a
24a
96cd


1/ All plots, including the controls were fumigated with 1,3D
(Telone II) at 6.0 gallons/acre in-the-row (40 inch spacing)
on 15 December 1978.

2/ A = at plant application, B = 35 days, C = 45 days, D = 55
days, E = 65 days, and F = 76 days after planting, respectively.
Numbers indicate lbs ai/acre. T = aldicarb at 3.0 lb ai/acre
in-the-row. Values followed by the same letter do not vary
significantly via Duncan's Multiple Range Test (P = .05).












Table 2. Effects of soil nematicide treatments and foliar applica-
tions of Vydate 2L on percent tubers affected by corky
ringspot disease (CRS). 1980 Experiment.1/


Soil nematicide3/,4/
Telone II
Vydate + Vydate
treatment2/ Telone II Temik 15G Temik 15G Control means


3+2+0+0 4.7ab 0.Oa 0.7a 7.3ab 3.2A

3+1+1+0 10.7b 0.7a 1.3a 12.Ob 6.2A

0+2+2+1 6.0ab 1.3a 0.7a 4.0ab 3.0A

0+0+0+0 43.3c 5.3ab 4.7ab 52.7c 26.5B


Nematicide
means 16.2B 1.8A 1.8A 19.OB


1/ Number of tubers with CRS lesions was determined by examing
random samples of 30 tubers from each plot and scoring CRS on a
presence-absence basis.

2/ Values in column are lb ai oxamyl/acre applied to foliage 41,
50, 60, and 70 days after planting, respectively.

3/ Telone II was applied at 6.0 gal 63 days before planting and
Temik 15G at 3.0 lb ai/acre in-the-row when the crop was
planted.

4/ Values followed by the same letter do not vary significantly
(P = .05) via Duncan's Multiple Range Test. Lack of a letter
denotes nonsignificance.












Table 3. Population densities of trichodorid (stubby root) nema-
todes at harvest following treatment with soil nematicides
and foliar applications of Vydate 2L. 1980 Experiment.


Soil nematicidel/'/,l4/
Telone II
Vydate + Vydate
treatment2/ Telone II Temik 15G Temik 15G Control means


3+2+0+0 9.0 2.4 4.0 7.4 5.7A

3+1+1+0 9.2 3.0 8.4 5.8 6.6A

0+2+2+1 7.0 2.4 2.4 0.0 3.0A

0+0+0+0 35.0 16.8 22.6 14.8 22.3B


Nematicide
means 15.0B 6.2A 9.4B 7.0A


1/ Nematodes/100 cm3 soil.

2/ Values in column are lb ai oxamyl/acre applied to foliage 41,
50, 60, and 70 days after planting, respectively.

3/ Telone II was applied at 6.0 gal 63 days before planting and
Temik 15G at 3.0 Ib ai/acre in-the-row when the crop was
planted.

4/ Values followed by the same letter do not vary significantly
(P =.05) via Duncan's Multiple Range Test. Lack of a letter
denotes nonsignificance.







-6-


Table 4. Total yields of US Size A potato tubers
soil nematicide and different Vydate 2L
Experiment.


as affected by
treatments. 1980


Soil nematicide2/,3/,_/
Telone II
SVydate + Vydate
treatmentl/ Telone II Temik 15G Temik 15G Control means


3+2+0+0 277 288 292 284 285BC

3+1+1+0 307 307 306 292 303A

0+2+2+1 290 290 309 261 291AB

0+0+0+0 277 277 295 243 276C


Nematicide
means 288 297 301 270


I/ Values in column are lb ai oxauyl/acre applied to foliage 41,
50, 60, and 70 days after planting, respectively.

2/ Cwt/acre

3/ Telone II was applied at 6.0 gal 63 days before planting and
Temik 15G at 3.0 Ib ai/acre in-the-row when the crop was
planted.

4/ Values followed by the same letter do not vary significantly
(P = .05) via Duncan's Multiple Range Test. Lack of a letter
denotes nonsignificance.














Table 5. Population densities of Belonolaimus longicaudatus (sting
nematode) at harvest following treatment with soil nema-
ticides and foliar applications of Vydate 2L. 1980
Experiment.


Soil nematicidel/,3/,4/
Telone II
Vydate + Vydate
treatment2/ Telone II Temik 15G Temik 15G Control means


3+2+0+0 0.8a 3.8ab O.Oa 45.6cd 12.6A

3+1+1+0 2.4ab 2.2ab 0.Oa 63.0d 16.9A

0+2+2+1 1.6ab 3.0ab 0.8a 26.2c 7.9A

0+0+0+0 4.6ab 14.8b 3.0ab 98.8e 30.3B


Nematicide
means 2.4A 6.0A l.0A 58.4B


1/ Nematodes/100 cm3 soil.

2/ Values in column are lb ai oxamyl/acre applied to foliage 41,
50, 60, and 70 days after planting, respectively.

3/ Telone II was applied at 6.0 gal 63 days before planting and
Temik 15G at 3.0 lb al/acre in-the-row when the crop was
planted.

4/ Values followed by the same letter do not vary significantly
(P = .05) via Duncan's Multiple Range Test. Lack of a letter
denotes nonsignificance.













Table 6. Population densities of Meloidogyne incognita
nematode) at harvest following treatment with
ticides and foliar applications of Vydate 2L.
Experiment.


(root-knot
soil nema-
1980


Soil nematicidel/,3/,4/
Telone II
Vydate + Vydate
treatment2/ Telone II Temik 15G Temik 15G Control means


3+2+0+0 2.4 554.8 145.6 491.6 298.6

3+1+1+0 3.0 359.8 0.0 588.6 237.8

0+2+2+1 24.6 212.6 74.2 408.6 180.0

0+0+0+0 7.4 626.8 6.6 590.0 307.7


Nematicide
means 9.4A 438.5B 56.6A 519.7B


1/ Nematodes/100 cm3 soil.

2/ Values in column are Ib ai oxamyl/acre applied to foliage 41,
50, 60, and 70 days after planting, respectively.

3/ Telone II was applied at 6.0 gal 63 days before planting and
Temik 15G at 3.0 lb ai/acre in-the-row when the crop was
planted.

4/ Values followed by the same letter do not vary significantly
(P = .05) via Duncan's Multiple Range Test. Lack of a letter
denotes nonsignificance.













Table 7. External tuber quality as affected by soil nematicides
and foliar applications of Vydate 2L. 1980 Experiment.!/


Soil nematicide3/,4/
Telone II
Vydate + Vydate
treatment2/ Telone II Temik 15G Temik 15G Control means


3+2+0+0 1.8ab 1.3a 1.2a 2.2ab 1.6A

3+1+1+0 2.4ab la -l.la 3.3b 2.0A

0+2+2+1 1.7ab la la 1.9ab 1.4A

0+0+0+0 5.1c 2.2ab 1.2a 6.4c 3.7B


Nematicide
means 2.8B 1.4A 1.2A 3.4B


1/ Tuber quality was rated on a scale
of defects and 10 = all tubers 100
tially nonsaleable as table stock)
grading table.


of 1-10 (1 = all tubers free
percent affected and essen-
as tubers passed across a


2/ Values in column are lb ai oxamyl/acre applied to foliage 41,
50, 60, and 70 days after planting, respectively.

3/ Telone II was applied at 6.0 gal 63 days before planting and
Temik 15G at 3.0 lb ai/acre in-the-row when the crop was
planted.

4/ Values followed by the same letter do not vary significantly
(P = .05) via Duncan's Multiple Range Test. Lack of a letter
denotes nonsignificance.




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