ANNUAL REPORT
Control of Nematodes
and Other Potato Pests
The following is a report of the 1938 season's work on nematode and
other potato pest control in Central and Southern Oregon for which funds were
provided under Item 1 of NB 465 by the 1937 Legislature.
Objective-- The chief objective of the research work as carried out in this
project has been to find practical control measures for the root-knot noratode
(Heterodora marioni) that has been causing considerable economic loss to
potato growers of the Klamath and Deschutes areas and to the clover seed growers of the Grants Pass and Deschutes areas. In addition to the main project
as listed some funds and time have boon devoted to scab and rhizoctonia of
potatoes studies in the Klamath area, and to problems of other crops that may
be used in rotation in high irrigated areas.
Root-knot Nematode Infestations
Deschutes County
Three days were spent during the middle part of September 1938 making
a preliminary survey of the Deschutes area to determine something of the extent
of the root knot nematode infestation.in that section. The writer was accompanied on this survey by Mr. Wilbur D, Courtney, Nematologist, U.S.D.A. The
areas checked were as follows: Terrebonne, North West Redmond, Cloverdale,
Sisters, Pleasant Ridge, Tumalo, Arnold, Alfalfa and Grange Hall. Infestations
had previously been reported from the Tumalo and North West Redmond sections
but had not been reported from the Terrebonno, Pleasant Ridge, or Grange Hall
sections where the survey showed heavy infestions. The Torrobonne section
showed particularly heavy infestation at every point chocked.
No nemic infestation was found in the Sisters, Arnold, Alfalfa or Cloverdale sections. There have been relatively few potatoes grown in these areas
and it is probable that the worm has not been introduced. More intensive surveys
are needed to determine their freedom from the worms,
Crook County
No control work is being done in this county. A hasty survey was made,
however, to see if there were any infestations. Only one infestation in the
Powell Butte area had been found previously. One comparatively light infestation was found in the Powell BUtte section but the Lone Pine area appeared
widely and heavily infested.
Josephine County
No attempt was made to survey this area but the worm has been reported
from points covering most of the Grants Pass area,
Klamath County
The intensive nematode survey under the direction of Mr, Eric Wold,
county pest inspector, was continued in the Klamath Basin during the 1938 season.
GRAPH I
RELATION OF SOIL TEMPERATURE
TO LENGTH OF ROOT-KNOT
NEMATODE LIFE CYCLE
60
(,5
5
0
80
7; mpe re teitv - aNx.ee..s hziht.ei?h ell
01041-man ternjoercthire lot-Potato Frowl% — Un I verse ol
friMoesolii Ayr. Lrp. S hi. 7ech. a u I. /14.341,
-
-
remioetkilitpe cea-ve cc;Vciilated 0/ 7 basis al io,a00 Cetih
A;ide-hoz/ps above /2 ° C. #2er yellefreilY01 7 4: le 7 W/7SC/Xiii
. 11/7/1Ver-slik of Haryck 49 1 /. k;rp• S/ gid. 44.309.
.
.
4
-
---
-
3
This survey has revealed a number of infestations not previously found or
reported. Some of the farms carry a small infested area while others are
generally infested.
On some farms the nemas have been responsible for considerable loss to
potato growers. One badly infested field checked at digging time had nineteen
per cent of the tubers showing external symptoms. It has also been observed,
during the past two years, that certain farms having what appeared to be an
equally heavy noma oopulation in the soil (indicated by knots on roots of
weeds and potatoes) took practically no loss of potatoes at sorting time.
In an effort to shed some light on this difference in number of infested
tubers, Mr. Weld and the writer cooperated in taking some soil temperature
readings during August and September to determine if differences in irrigation practices would change soil temperatures enough to be a factor. Work
done by G. R. Townsend (Graph I) indicates that the amount of infestation on
beans is directly in relation to the soil temperature. From the observations
and the temperature readings obtained it was found that rather wide differences
in soil temperatures did exist on farms in the same district having similar
soil, and that these differences followed rather consistently differences in
irrigation
practice, Fields having an average daily temperature of around
°
irrigated every three to five days, Fields having temperatures
63° - 65 F. were
0
as high as 75 - 80° F. were irrigated less frequently - around seven to nine
days. In checking tubers from these fields at digging time no external symptoms
were found on tubers from the field having low average temperatures. Yet roots
of weeds and potatoes indicated a heavy and general nematode population.
Another field having high average temperatures produced tubers with nineteen
per cent showing external symptoms.
It appears, on the basis of present information, that the worms overwintering in the soil attack the roots of plants before irrigation begins
and before tuber formation begins and if the soil temperature is kept law,
around 63°F., the nematodes are slowed down in their development enough to
allow tuber maturity before a new generation of larva are freed into the soil.
A controlled experiment is planned for the 1939 season to determine
the accuracy of the above observations and to get mere definite information
as to the optimum frequency of irrigation for tuber production and nematode
control.
Plot Technique
Deschutes County
The area under observation in Deschutes county was all planted to winter
wheat. Portions of the field wore treated with selective sprays to kill weeds,
At the time of spraying, however, few weeds had started and a month later no
differences in weed population could be observed. Also a square rod plot in
the wheat was treated with chlorpicrin at 200 pounds per acre.
Josephine County
The experimental area in Josephine county was divided into two parts
in 1937- one half was fallowed and the other half planted to sweet corn, For
the 1938 trials each half was divided into three parts. These were laid out so
that each headed at the irrigation ditch and could be irrigated separately with
4
A portion of the Josephine County nematode control plots are
shown in the foreground of the photograph. In these trials spring
barley gave better control than did either corn or fallow.
Hoot•knot nematodes are responsible for heavy losses to Ladino
clover seed growers in this region.
5
a minimum of danger of water running from one plot to another. Each plot was
plowed and cultivated as a unit.
Klamath County
The Klamath plots represent the bulk of the work and inasmuch as they
could be watched closely were laid out and handled with special care to prevent
contamination from one plot to another. here forty-two tenth acre plots were
laid out side by side. Each plot was separated with a three foot ditch to
prevent irrigation water from running from one plot to another. The banks
thrown up by the ditcher served as borders to hold water on the desired plot,
A sixteen foot alley was left along the upper and lower ends of the
plots and was kept fallow. The alleys facilitated handling the plots and the
fallow was designed to assist in preventing spread of infestation by machinery
during cultivation.
In cultivation plots with similar treatments were handled as units and
the equipment was cleaned before being put on other units.
Soil Sampling Technique
A "gopher" shovel (similar in design to a tile shovel) was used in
sampling the plots. It was found that such a shovel was rapid and easily
cleaned. The blade was six inches wide and ten inches long with parallel sides.
In sampling, one shovel full the depth of the blade was first removed
in such a manner as to leave'a smooth surface on the cut. Then a thin slice,
about one inch thick, was cut from the smooth surface to the depth of the blade.
This slice was divided length wise. One half was discarded and the other half_
MRS saved for the composite sample.
Numerous such samples were taken at random over the entire plot with the
exception of a strip three feet wide along each side.
When all the samples from a plot had been taken, they were mixed on a
large piece of galvanized iron and three three-pound samples ( 0,000,000 acre
foot per sample) were weighed into half gallon Seal Rite ice cream containers.
The samples were brought to Corvallis in these containers and planted to tomatoes
in the greenhouse.
Supplemental heat was provided by placing sixty feet of electric soil
cable under the samples. A thermostat maintained the temperature at 78 0 F.
This temperature was close to the optimum (80 0 E.) for the nematodes but a
little high for the tomato plants, particularly during the seedling stage.
Considerable trouble was experienced with damping off of the tomato
seedlings. Some samples were replanted a third time, It is proposed to transplant into the soil samples next year in an attempt to got away from some of the
damping off. It is also thought that transplanting will tend to give more
uniformity in size of the plants and will speed up the time required to grow
the tomatoes. Three months were required this year.
Reading Samples
In reading the knots on the tomato roots, the soil was carefully washed
from the roots over a quarter inch mesh screen. The roots were then put in a jar
Nematode plot soil samples in Seal Rite containers
planted to tomatoes in greenhouse.
7
Nightshade (Solanum sp.). This is one of the best
indicator plants in cultivated fields during the summer
and early fall. In uncultivated fields and during the
winter and spring dandelion (Taraxacom officinale), a
perennial, and moth mullen (Verbascum Blattaria), a
biennial, are the best indicators of root-knot infestations.
Knots on nightshade roots.
of water and a few at a time were transferred to a petri dish partially filled
with water where they were counted. It was found that counting knots under
water served three purposes: (I) Assisted in separating small rootlets, (a)
made small knots more visible, and (3) kept roots from drying out. Very small
knots, about 1 mm. or less, could be seen readily under water when they were
hardly visible out of water.
The time required to read a sample varied from a half hour to three and
one half hours and averaged a little more than an hour for the entire lot of
195 samples.
Results of Nematode Trials
Deschutes County
Soil samples from this area were brought to the greenhouse in September
and planted to tomatoes. No supplemental heat was available at that time. The
growth of tomatoes was stunted. Twelve knots showed in only one of the six
samples from the untreated grain field and none showed on samples from the
Chlorpicrin treated area. This does not bear out observations made on roots of
nightshade growing in the grain during the summer. A heavier and more general
infestation existed than was shown by the soil samples.
Josephine County
Results of root-knot readings on soil samples from the Josephine county
trials are shown in Table I. These data are in reverse to those expected and
do not follow those from the Klamath county trials.
The marked reduction of nematodes in the barley plots can be accounted
for only through the method in which they were handled. It was originally
during the fall of
intended that the barley plots should be planted to OAC
1937. Fall rains delayed the planting until March 1, 1938. A very thin stand
resulted and the weed population was high. The whole experimental area was
plowed on the 15th, 16th, and 17th of April and the barley plots were replanted
to the Hannchen variety, which stools freely. It is thought that the late
February harrowing that the barley plots received in preparation for sowing
may have been the chief factor in the reduction of nenatodes. Weeds were
allowed to grow on the remaining plots until plowed in April.
e
The whole plot area was seeded to Ladino clover by the owner in late
October, 1938. Occasional checks will be made on the roots of the clover for
nematode infestation during the 1939 season..
TABLE 1
Results of Greenhouse Tests of Soil Samples
From Josephine County Nematode Plots
Showing Number of Knots per Sample
Plot
Nos.
1
2
3
4
5
1937
Fallow
Do
Do
Corn
Do
Sample Nos.
Plot Treatment History
Do
6
No plants grew in sample 2 of plot 5
1938
Barley
Corn
Fallow
Barley
Corn
Fallow
1
16
69
122
35
129
146
2
19
134
103
53
191
•
Ave.
18
102
113
44
129
169
10
Klamath County
Cropping and cultural practices on the Klamath County plots are shown in
Table 2 and summarized in Table 3 and Graph 2. It will be noted that only
one of the six samples from the two-year fallow plots showed root-knots. It
is felt that possible contamination at time of sampling may account for them.
Regardless of whether or not it is contamination two-year fallow is the most
effective control method tried to date. One-year fallow shows a large reduction.
Harrowed spring wheat plots show a pronounced increase of nemas. It is
thought this has a direct connection with the number of weeds. The harrowing
was done to kill the weeds, but the spiketooth harrow available for this
purpose took out about half the wheat, As a result weeds, particularly nightshade which is an excellent host for the nematodes, came in thickly. A less
severe harrow used two or three times may prove effective in removing the weeds
without material injury to the grain. Harrowing appears to have been of some
advantage in winter grain. More work is proposed along this line.
The use of selective sprays on grain to kill weeds without injury to
grain was attempted only on the winter grain. By the time the spraying could
be done the grain was so high and thick that good coverage of the weeds could
not be obtained. The weeds also were too far advanced for the sprays to kill
effectively. They were set back about two weeks but little kill resulted.
Of the sprays used (6per cent sulfuric acid, 20 per cent ammonium
sulphate,
sulphate, 2 per cent and 1-1/2 per cent sinox each at 120 gallons per acre)
2 per cent sinox gave the most promising results. No damage to the grain was
noticed with this spray and it was more severe on the weeds. Tansy mustard
was the principal weed. Both sulfuric acid and ammonium sulphate burned the
grain to some extent.
In Table 2 it will be noted that rather wide variations in number of
knots occur in samples from the same plot. It was found that in samples from
the same plots those having the greater average height of plants also had the
greatest number of knots. This was true in 62 per cent of the instances. In
27 per cent of the instances the samples having the greater average height of
plants had the smallestnumber of knots, and in all per cent the median number.
It is thought that transplanting an equal number of plants similar in vigor
will tend to correct some of the variation due to size of plants as it reflects
root development.
11
Harrowed Marquis wheat plots. Spike—tooth harrows take out
much of the grain leavin ideal conditions for weed growth.
12
TABLE 2
Results of Greenhouse Tests of Soil Samples
From Klamath County Nematode Plots
Showing Number of Knots Per Sample
Plot
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
15
16
17
18
19
20
21
22
'23
24
25
26
27
28
29
30
31
32
33
34
36
37
38
39
40
41
1938 Crop
Winter Wheat hay (Sprayed)
Winter Rye hay (Sprayed)
Spring Wheat
Fallow - 2 years
Winter Wheat
Winter Wheat (Harrowed)
Winter Wheat (Sprayed)
Winter Rye (Sprayed)
Winter Rye (Harrowed)
Winter Rye
Spring Wheat
Spring Wheat (Harrowed)
Spring Wheat.
Spring Barley
Spring Barley (Harrowed)
Spring Barley
Fallow 1 year
Spring Wheat
Spring Wheat
011i Barley
Winter Wheat hay (Sprayed)
'Winter Rye hay (Sprayed)
Spring Wheat
Fallow - 2 years
'tinter Wheat
Winter Wheat (Harrowed)
Winter Wheat (Sprayed)
Winter Rye (Sprayed)
Winter Rye (Harrowed)
Winter Rye
Spring Wheat
Spring Wheat (Harrowed)
Spring Wheat
Spring Barley
Spring Barley (Harrowed)
Spring Barley
Fallow 1 year
Spring Wheat
Spring Wheat
Alfalfa Check
-10
173
662
0
546
44
122
21
91
27
103
2844
801
235
162
533
98
321
74
22 6
248
142
164
0
640
33
112
122
113
142
176
8
155
37
'71
25
0
287
23
426
.
Samples
-2135
41
247
11
271
235
32
13
414
229
421
975
1337
725
170
263
2
403
355
24
23
6
57
0
692
44
45
243
52
33
119
37
1
65
81
17
3
302
7
576
-3-
Ave.
93
70
16
0
164
19
12
5
43
270
698
1052
536
457
428
222
1
179
322
6
40
47
61
0
3
119
36
90
62
34
159
106
76
95
308
4
327
100
55
13
183
175
407
1624
891
472
253
339
34
301
250
85
103
65
94
0
445
65
64
152
76
70
151
50
81
57
66
25
1
260
30
374
.....
68
45
32
1
190
59
120
,
13
TABLE 3
Results of Greenhouse Tests of Soil Samples
From Klamath County Nematode Plots
Showing Average Number of Knots Per Sample
Plot Treatment History
Plot
No.
1-22
1937
1st Crop Alfalfa & Fallow
2-23
Do
3-24
4-25
5-26
6-27
7-28
8-29
Do
9-30
10-31
11-32
12-33
13-34
14-35
15-36
16-37
17-38
18-39
19-40
20-41
21
1938
Fallow
Do
Do
Do
Do
Do
Do
Spring Wheat
Do
Do
Do
Spring Barley
Do
Do
Do
Cynamid & Fallow
CS 2 & NaBO Fallow
2
Fallow
Alfalfa Check
Winter Wheat
Hay (Sprayed)
Winter Rye hay
(Sprayed)
Spring Wheat
Fallow
Winter Wheat
Do (Harrowed)
Do (Sprayed)
Winter Rye
(Sprayed)
Winter Rye
(Harrowed)
Winter Rye
Spring Wheat
Do
(Harrowed)
Spring Wheat
Chemical*
Spring Barley
Do
(Harrowed)
Spring Barley
Fallow
Spring Wheat
Do -
011i Barley
1st
Plot
2nd
Plot Ave.
Check
76
103
89
23.8
95
65
80
21.3
308
4
327
55
13
94
0
445
65
64
152
201
2
386
83
60
83
53.4
.5
103.2
22.2
16,0
22.2
183
76
130
35.0
175
407
1624
70
151
50
123
279
837
32.9
74.6
223.8
891
81
486
129,9
472
253
57
66
265
160
70,9
42.8
339
25
182
17
281
140
85
374
48.7
4,6
75.1
37.4
22.8
100.0
100
34
301
250
85
-
1
260
30
-
374
* Plots 14 and 35 divided into thirteen plots each for chemical trials with
carbon bisulphide and chlorpicrin. Results shown in Table No. 5
In selecting a grain crop to use in rotations for nematode control it
should be chosen with a number of things in mind. First, it should be one that
tillers heavily producing a thick stand and assisting to control ueeds4 second,
it should have the ability to withstand harrowing; and third, it must produce
a good yield of marketable grain.
Differences in ability to ulthstand harrowing was readily observed between
the spring wheat and spring barley used in these trials. Marquis, the spring
wheat used, tillered sparingly, while Hannchen, the spring barley,tillered
abundantly. After harrowing only about a half stand of 'Marquis remained.
Hannchen, on the other hand, suffered much less damage. The result so far as
nematode, control is concerned is shown in Table 4. Harrowed Marquis plots had
three times as many knots as unharrowed plots. Harrowed Hannchen plots had less
knots than the untreated plots !
■
Per
0
fa // 0 w
years
// w
/ yea r
Wmted- !'Whea t
oltpy ec/
O
Ryeiky
.5,0 ,-ay cc/
Win
Winter Wheat
rowed
Winter Rye.
.Sprayed
p fr-/Avy Barley
W /pre is Wheat Hay
- 5 7119
,
eci
Wolfe ,- Ry e
erro wed
-5121-
ilalra
o le icleY
Spring Wheat *"
spr-inq Carley
4/(a/fa Check
,Spring Wheat'
.
VVheai
Wheat'
Ncyrrovv ed
-5pi-//79
Gent
15
A thick stand of Hybrid #63. Such stands assist:
materially in controlling weeds.
16
TABU', 4
Effect of Harrowing on Spring Grain
Untreated
Hannehen
Harrowed
277
837
..................... 228.......... 160
New Wheat Variety
Washington Hybrid #63 wheat was introduced to the Klamath Basin for the
first time and was used in connection with these trials. In addition to showing excellent results in reduction of nematode population, this wheat yielded
50 bushels an acre, while spring-planted Marquis, the standard variety for the
region, yielded only 35 bushels an acre under comparable conditions. This
variety gave not only better nematode control than the Marquis, but out-yielded
it 15 bushels an acre. Hybrid 63 has further advantages: (1) It becomes well
established in the fall and provides good soil cover while considerable trouble
is experienced with the blowing out of spring-planted varieties; (2) Reduced
use of irrigation water; and (3) Earlier harvest and therefore better opportunity
to establish stands of alsike clover by sowing on the stubble during the summer.
Most winter wheats head so early that they are subject to damage by late
spring frosts. The late heading habit of Hybrid =03 makes it especially well
adapted to this region.
The use of this variety when applied to the Wheat acreage of the Klamath
Basin, will pay for the total cost of this experiment many times over,
-
Chemical Trials
Chlorpiorin at 100 and 200 pounds per acre and carbon bisulphide at 247
gallons per acre in 16-in. staggered holes were applied in the chemical plots,
These plots were installed with the cooperation of Mr. Wilbur D. Courtney,
Nematologist,USDA. They are a square rod in area.
The treatments were made with an applicator designed and built by
Mr. A. L. Taylor who is in charge of nematode disease investigations in Georgia,
With this equipment a square rod plot could be treated in ten to fifteen minutes.
Cost of these materials is high for field use. Chlorpicrin cost one
dollar per pound and the carbon bisulphide can be obtained at sixty-five cents
per gallon in large quantities.
Results of the chemical trials are shown in Table 5. The control obtained
with carbon bisulphide is outstanding showing less than one.half of one per cent
of the infestation found in the cheeks. Both concentrations of chlorpicrin on
the other hand show an increase over the checks.
It was originally planned to plant these plots to an indicator crop and
make the readings directly out of the field. The yellow goose-neck variety of
summer squash was reported by Mr. Taylor of Georgia to be an excellent indicator
here. It was used in these trials but proved very unsatisfactory. The crop
did serve very well, however, to show the effects of the treatment upon the growth
17
Nematode Lontrol plots in Klamath County. The central plot
is Series II of the chemical trials. The noticeably stunted squash
plots were treated with carbon bisulphide.
18
of plants. The growth in the chlorpicrin treated plots was markedly more abundant
than in the checks. On the other hand the growth in the carbon bisulphide
treated plots was extremely stunted. The plantings were made three weeks after
treatment but the soil was not stirred after treating and before planting.
TABLE 5
Results of Greenhouse Tests of Soil Samples
From Klamath County Nematode Plots
Showing Number of Knots Per Sample
--Chemical Plots --Series I
No.
Plot No. 14
Treatment
1
2
3
4
5
6
7
8
9
10
11
12
13
Check
Chlorpicrin
Do
Carbon bisulphide
Check
-Chlorpicrin
Do
Carbon bisulphide
Check
Chlorpicrin
Do
Carbon bisulphide
Check
Series II
1
2
3
4
5
6
7
8
9
10
11
12
13
Plot 35
Check
Carbon bisulphide
Chlorpicrin
Do
Check
Carbon bisulphide
Chlorpicrin
Do
Check
Carbon bisulphide
Chlorpicrin
Do
Check
Rate per
Acre
100 lbs.
200 lbs.
247 gals.
100 lbs.
200 lbs.
247 gals.
100 lbs.
200 lbs.
247 gals.
247 gals.
200 lbs.
100 1ips,
247 gal's.
200 lbs.
100 lbs.
247 gals.
200 lbs.
100 lbs.
1
Sample No.
2
Ave.
357
287_
93
2
89
126
230
0
267
226
191
0
297
341
306
94
0
237
188
201
1
291
237
439
0
72
349
297
94
1,
163
157
215
1
280
231
315
0
185
112
0
118
632
465
2
57
114
2
2
531
871
892
22
0
1403
279
4
0
554
38
42
1
544
2510
288
67
0
761
456
235
1
306
76
22
2
538
1691
590
Summary of Chemical Plots
Series I
244
Checks
1
Carbon bisulphide
247 gals.
228
100 lbs.
Chlorpicrin
208
200 lbs.
Chlorpicrin
Series II
236
228
1
1
741
485
518
363