NEMATODE POPULATIONS IN
by
Harvey L. Martignoni Jr.
A thesis
submitted in partial
fulfillment of the requirements for the degree of
Master of Science in the School of Agricultural Sciences
Fresno State College
May, 1971 AUTHORIZATION FOR REPRODUCTION
OF MASTER'S THESIS
I do not approve the reproduction of all or part of this thesis. ACKNOWLEDGEMENTS
I would like to express my sincere appreciation to
Professor Robert D. Harrison, Dr. James R. Brownell, and
Mr. Edward R. Hasbrouck for their suggestions and assist ances in the preparation of this manuscript.
I would like to extend my appreciation to Dr. Merlin
W. Allen, University of California, Davis, California; staff members of the Bureau of Plant Pathology, Sacramento,
California; and staff members of the state Department of
Water Resources for their help in providing the necessary information or materials from which this study was conducted.
I would like to thank my family and friends for their moral support and encouragement in my educational endeavors.
Lastly, more than anyone I owe much to my wife, Betty, who offered useful advise, typed and re-typed the manuscript.
Without her participation, continuing patience and inspiration this effort would not have reached completion. TABLE OF CONTENTS
Page ACKNOWLEDGEMENTS iv
LIST OF TABLES vi
LIST OF ILLUSTRATIONS vii
INTRODUCTION 1
1. Objectives 2
LITERATURE REVIEW 4
THE STUDY AREA 8
METHODS 16
1. Sampling 16
2. Extraction 17
3. Counting 18
RESULTS AND DISCUSSION 19
1. Optimum sample size 19
2. Estimates of vertical distribution .... 24
3. Estimates of horizontal distribution ... 25
4. Estimates of total population 36
5. Analysis of water samples ...... 38
CONCLUSION 42
LITERATURE CITED 44 LIST OF TABLES
Table Page 1. The mean number of nematodes per sample size and the variation within sample sizes...... 22
2. The location of the sampling sites in the north^and south sections of the North San Joaquin Division and the sampling periods... 31
3. The location of the sampling sites in the north_and south sections of the San Luis Division and the sampling periods 32 LIST OF ILLUSTRATIONS
Figure _ Page 1. A map Oi California showing the California Aqueduct and the Operation and Maintenance Field divisions 9
2. A map of the North San Joaquin Division showing the California Aqueduct and the major features in the division. 10
3. An aerial photograph of the California Aqueduct in the North San Joaquin Division. 11
4. An aerial photograph of the Delta 11
5. A map of the Sacramento-San Joaquin Delta showing the waterways that converge in the Delta 12
6. An aerial photograph showing the San Luis Reservoir and 0 Neill Forebay 13
7. A map of the San Luis Division showing the California Aqueduct and the major features in the division 14
8. The mean number of nematodes per reading among the various sample sizes... 20
9. The mean number of nematodes per gallon of water among the various sample sizes 23
10. The mean number of nematodes per reading at various sampling depths 26
11. The 1970 water flow pattern for the North San Joaquin Division and the San Luis Division..... 27
12. A map of the California Aqueduct in the North San Joaquin Division showing the various sampling sites...... 29
13. A map of the California Aqueduct in the San Luis Division showing the various sampling sites, 30
14. The mean number of nematodes per gallon of water extracted at weekly intervals in the north and south section of the North San Joaquin Division 33 LIST OF ILLUSTRATIONS - continued
Figure Page
15e The mean number of nematodes per gallon of north £5raCt?2 St W?ekly Lntervals in the north^ and south section of the San Luis Division. 35
16. The mean number of nematodes per gallon of water^extracted from the North San Joaquin Division and the San Joaquin Division 37 17. Estimated number of nematodes per day passing the^various sampling sites during the sampling periods 39 INTRODUCTION
The California Aqueduct, a man-made river which is part of the State Water Project, stretches 444 miles from the Sacramento-San Joaquin Delta to Perris Reservoir in
Riverside County. Along this artery, and through branch lines, surplus water from the north will be carried to the south where it will be used in industry, homes and irrigated agricultural land. The San Joaquin Valley will receive about one third of the State Water Project's water supply for land use. With project water, much of the sparse deseru-like westside grasslands will be developed for irrigated agriculture.
The quality of water is an important criterion for future water needs in irrigated and non-irrigated agri cultural lands. Increasing demands for water and a growing concern with rapidly increasing pollution problems have stimulated efforts in maintaining existing water quality. The abstract term "quality" takes on specific meaning when associated with specific water use, e.g. drinking, industry, recreation, agriculture, fish and wildlife protection, etc. The quality standards for irrigation water are based on the nature and total amount of dissolved salts. The amount of water used varies with the quality of the water, as well as with the method of irrigation, soil and drainage conditions, climate, and the type of crop. The dissolved mineral content in agri cultural water affects the amount of drainage water required 2 to maintain producti vi fu a^. 4 --u y. As the irrigation water is used
by the plant and evaporates the- m H. i ^ 4- ^ 1 • •. > o ne salts left behind must be
leached from the soil and carried off in drainage water.
Generally, the lower the dissolved mineral content, the
lower the requirements for leaching water and the greater
the possibility of reusing the drainage return water.
Another criterion for water quality is the possible
contamination of agricultural water with unwanted pests
(weed seeds, fungi spores, nematodes) from new or reused
return drainage water.
Of increasing concern is the possible contamination of
the California Aqueduct and the spread of these pests into
non-infested agricultural lands. The significance of the
California Aqueduct as a source of contamination has not
been assessed. Apparently, no sampling has been done to
study the role of the California Aqueduct as a potential
source of any of these unwanted pests.
The objectives of the present study were to obtain
information on some aspects of the possible nematode
contamination in agricultural water within a limited area
of the California Aqueduct. Specifically, this study was
designed to:
(1) Estimate the total nematode population.
(2) Estimate the horizontal and vertical distribution
pattern of the nematode population in the aqueduct.
(3) Determine the optimum sampling size for a study of this
type.
(4) Establish sampling techniques. 3 (5) Identify plant parasitic nematodes isolated from the aqueduct.
Since no investigations of a similar nature have been
conducted on the California Aqueduct, this study was largely exploratory in nature. LITERATURE REVIEW
Interest in the spread of nematodes in irrigation water has been expressed, but there are only a few pub lished reports. The occurrence of nematodes in agricultural drainage water was reported by Godfrey (1923), who invest5.gat.ed the alfalfa, stem nematode disease in the Pacific Northwest.
Godfrey stated, "The organisms may be carried for long distances by irrigation water. Waste water from infested fields carries the organisms by the millions. It may empty into a ditch that does duty lower down on the same farm or on an adjacent farm, or it may go back into a large lateral ditch or even a river, and thus be carried to another irrigation project miles away."
Thorne (1941) reported new colonies of sugar beet nematode established by irrigation water running over infested soil and picking up the cysts and larvae and depositing them along the furrows, or by reuse of infested irrigation water. In a similar study, Petherdridge and
Jones (1944) reported an instance of the spread of potato
eelworm cysts by flood water.
A number of workers have recovered nematodes from municipal water supplies. Chang, et al. (1959) found
Ohio River tap water containing motile nematode larvae of
microscopic size. Examination revealed densities of 1 to
20 nematodes per gallon were detected. In a later study,
Chang, Woodward and Kabler (1960) indicated that nematodes
are fairly common in Ohio Municipal water supplies from surface sources; of 22 city water systems investigated,
16 of the systems contained nematodes. Goodrich, Hechler, and Taylor (1968) reported the occurrence of predaceous nematodes m a water treatment plant in Illinois. Infor mation was not given on the method of collection and extrac tion.
In Spain, Gadea (1961) found nematode communities inhabiting several freshwater regions in the northern part of the Iberian Peninsula. In 1961, Gadea and Gallego reported the occurrence of nematodes in rice fields in some parts of Spain. The rice fields constituted a special biotope for nematodes. The fauna consisted of a mixture of predacious river-water forms and free living saprobionts, with a few accidentally present plant parasitic nematodes.
DuCharme in 1955 reported that spreading decline spread 25 feet uphill compared with 200 feet downhill in one year in a hillside citrus grove. He suggested that the percolation of soil water influences the direction and rate of burrowing nematode movement in such a way that they are able to travel to relatively long distances downward in a short time.
Fisher (1968), in a study on nematode population patterns, reported the presence of saprophagus, predaceous, and plant- parasitic nematodes in Lake Champlain, Illinois. Total populations reported were at maximum levels in midsummer and at minimum levels in May and October. Water temperature was cited as the primary cause of population fluctuations, while available nutrients were secondary. 6 In 1969, Heald and Johnson (16) reported on the survival and infectivity of nematodes pass'ed through an overhead sprinkler irrigation system. Even though Meloidogyne larvae, Pratylenchus, and Hoplolaimus (plant parasitic forms) were collected from water samples passed through an overhead sprinkler system, Heald and Johnson hypothesized that these forms were not capable of infecting nematode- free plants, and that this incapability was probably caused by the pressure change exerted on the nematodes at the pump or at the sprinkler orifices.
Estimates of population levels have steadily increased
as the result of improved sampling techniques. One of
the highest population counts on nematodes in irrigation
water was made by Faulkner and Bolander (1967), who gave
a figure of approximately 200 nematodes per gallon of
water in canals servicing the lower portion of Washington s
irrigated Yakima Valley. Approximately 10 to 20 percent
of the total population consisted of plant parasitic forms.
Faulkner and Bolander (1970) reported that the primary
source of plant parasitic nematodes in irrigation water
ways in the Columbia Basin Project of eastern Washington
is irrigation runoff water returned into the irrigation
system. Of the 17 sampling sites studied, the sampling
site located at the end of a drain below Quincy, Washington
revealed the highest seasonal averages, 5,319 plant para
sitic and 148,916 saprozoic nematodes/m3 (264.2/gallons)
of water passing over the site. 7 Faulkner and Bolander (1970) demonstrated that plant parasites introduced to non-infested land via contaminated water can become established 011 host plants. In their stuay, water from an irrigation canal and water from a deep well were used to irrigate plants growing in Methyl
Bromide fumigated screenhouse ground beds. Beds planted with alfalfa, bean, eggplant, mint, and sugar beet, and irrigated with canal water became heavily infested with a variety of plant parasitic nematodes while those receiving well water did not.
Although sampling techniques have improved, it is still very difficult to make meaningful comparisons between different kinds of habitats using recent popula tion estimates. The problem may be that inherent differences in populations are likely to be obscured by the even greater differences resulting from variations in sampling and extraction methods employed. Comparisons also are made difficult by the lack of a standard unxt or volume by wnicn
to express data, THE STUDY AREA
The areas selected for study were the North San Joaquin
Division (Delta Field Division) and the San Luis Division of the California Aqueduct (Figure 1).
The North Sa.n Joaquin Division extends 67 miles from the southern end of the Sacramento-San Joaquin Delta to
O'Neill Forebay (Figures 2,3). Waters of the Sacramento
River system and other rivers that flow out of the Sierra
Nevada Mountains converge from the North, East, and South toward the Delta (Figures 4,5). From there, the Delta
Pumping Plant lifts the water more than 240 feet from
Clifton Court Forebay, near Tracy, to Bethany Reservoir, for distribution into the California Aqueduct. Water in the aqueduct then flows into O'Neill Forebay for storage in San Luis Reservoir and/or for transportation south
(Figure 6). Pumps located at the base of O'Neill Darn also can take water from the Delta-Mendota Canal, which
parallels the aqueduct, through an intake channel and
discharges it into O'Neill Forebay. The North San Joaquin
Division contains 62.4 miles of open, concrete-lined canal
and 4.4 miles of channel and reservoir. The width and depth
of the canal vary. At its widest point, it is 138 feet
across the top, 40 feet across the bottom, and 30 feet deep.
The San Luis Division extends 106 miles from O'Neill
Forebay to Kettleman City (Figure 7). Water for irrigation
is released from O'Neill Forebay and/or the San Luis Dam
into the aqueduct and flows 18 miles to Dos Amigos Pumping OPERATION AMD A1NTE N AMCE FIELD DIVISIONS
„. I A MON o f California showing the California Aqueduct^and the Operat ioti aad Maintenace Field Division. CLIFTON COURT ( FOREBAY V INTAKE CHA NNEL 8 | FISH PROTECTION WO RKS J » PERIPHERAL DELTA \ ^ CANAL // PUMPING PLANT \ I ^
BE THA N r"" Vv\^ 7 \XRESERVOIR M,-y LIVER MORE v © # €# 9 TRACY P.P. ^STOCKTON
MANTECA xCALIFORNIA VERMALiS^
WESTSTCEF FREEWAY
•( MODESTO
WESTLEY
/// l! PAT7ER30H >.AQUEDUCT
CROWS LANDING TURLOCK O,N E^! LI r> PUMPING PLANT NEWMAN S. /• FEDERAL )
SUSTINE
t /ff' O'NEILL SLUt FOREBAY
VOLT A
MERGE LOS SAN LUIS DIVISION BANGS
Fimure 2. A map of the North San Joaquin Division showing the California Aqueduct and the major features in the division. 11
Figure 3. An aerial photograph of the California Aqueduct in the North San Joaquin Division.
Figure 4. An aerial photograph of the Delta.
Figure 6. An aerial photograph showing the San Luis Reservoir and O'Neill Forebay. 1.
•HIGHWA Y 152 RELOCATION SAN LUIS RESERVOIR N. SAN JOAQUIN DIVISION AND PUMPING - GENERA 77 NG PLANT O'NEILL FOR EBAY O'NEILL PUMPING PLA, ( FE D ERAL )
v LOS BANOS / DETENTION RESERVOIR
DOS AM/GOS PUMPING PLANT DELTA MEN DOTA —•CANAL \ LITTLE PANOCHE i federal} A DETENTION RESERVOIR DPOALSO S T\ SIPHON
PANOCHE CREEK | SIPHON FiREBAUGH
^CALIFORNIA AQUEDUCT
PLEASANT VALLEY CANAL AND PUM PING PLANT /P-- {FEDERAL) //
OIL CITY ©
COALINGA
AVENAL MILES
.^kettleman
it- 7 A m aD of the Sail Luis Division showing the California Aqueduct and the major features m the diJ * vi* si* on. Plant, where it is lifted 117 feet to allow for gravity flow to the division terminus at Kettleman City. The
California Aqueduct from O'Neill Forebay to Kettleman
City releases water to customers through turnouts along this section of the aqueduct. The San Luis Division contains 103.5 miles of open concrete-lined canal, 257 feet across the top at its widest point, 110 feet across the bottom, and 36.8 feet deep; and 2.2 miles of channel and reservoir. METHODS
1. Sampling
Pilot samples were taken on February 21 and on March
25, 1970. The February 21 samples were taken from the bridge crossing the aqueduct at San Mateo Avenue. A plankton tow net with a Koroseal glass vial adapter was used to collect water samples. The net was lowered into the aqueduct for periods of 5 to 10 minutes and then recovered. The contents of the net were washed with deionized water into 45 ml, glass vials. The vials were labelled and information recorded. The vials were placed in metal racks and transported to the Nematology Laboratory at Fresno State College. The contents of the vials were
processed using the method of Christie and Perry (1951)
and then examined under a dissecting microscope.
Water samples collected on March 26 were taken from
arbitrarily selected points along the aqueduct in the San
Luis Division. A compact self-priming marine utility
pump (12 volt D.C. battery powered) fitted with a 3/4
inch diameter hose was used to pump water out of the
aqueduct. One, two, and five gallon water samples were
pumped through a series of sieve screens. The residue
left on the screens was washed into glass vials. The
vials were taken to the laboratory and the contents of
the vials were filtered and examined. Sampling began in June and was terminated in September,
1970. Bridges crossing straight stretches of the canal 1 and with open access roads were used as sampling sites.
The North San Joaquin Division and the San Luis Divis5.on were divided into two sections and each section was sampled weekly. Water samples were collected with a depth adjustable sampling hose (one inch diameter dairy hose). A one inch cadmium plated steel suction strainer with a 15 pound stream lined weight was attached to the sampling hose. The sampling hose was connected to a 2 horse power gas-driven centrifugal
pump fitted with a vacuum and pressure guage. Sample size
was controlled by pumping timed volumes of water at fixed
total pressure through stacked 20, 32, and 400 mesh (pore
size 0.480, 0.340, and 0.025 mm respectively) Tyler sieves.
The residue remaining on the 400 mesh sieve was washed
with deionized water into a 45 ml glass vial. A plastic
funnel was used to facilitate transfer of residue into vials.
The vials were marked and information recorded. The vio-ls
were placed in metal racks and transported to the labora
tory. Measurements of water temperature were taken with a
laboratory thermometer at each sampling site during sampling.
PH of water samples was measured with a Coleman model
38 pH meter after water samples were taken back to the labora
tory.
2. Extraction In this study, nematodes were extracted from the water
samples by a modification of the method of Taylor (1961).
The contents from the collecting vials were washed with 18 deionized water into 7 oz. plastic cups. The cups were covered with tissue (Kimwipe Disposable wipers, type 1300's) secured with a rubber band. The cups were inverted over
3 partitioned plastic petri dishes (15 mm by 100 mm). The petri dishes were filled with water. The cups were numbered and marked. The inverted cups were allowed to remain at a temperature range between 72°C - 75°C for a period of
24 hours to allow the nematodes to pass through the filter into the partitioned petri dishes.
3. Counting
Nematode populations were estimated by washing the contents of a partitioned petri dish into a 20 x 100 ml glass counting dish. The counting dish was placed on a square glass plate with 10 equal subdivisions. This apparatus was placed under a 3-D variable steriozoom dissecting microscope. An eight key Clay-Adams laboratory counter was used to count populations. A Doncaster Counting dish (perspex type counting dish with concententric channels) was used periodically to recheck population counts. After counting, the nematodes were killed with heat and placed in 15 ml plastic vials and fixed in TAF, Triethanolamine
Formalin Fixative, (Courtiney, Dolley and Miller, 1955).
Vials were recorded and stored for further examination. RESULTS AND DISCUSSION
Analysis of the data obtained in the pilot studies
indicated low nematode populations in the aqueduct as
compared to other studies (1,7,8). Were these populations
typical of the water habitat in the aqueduct or was the
sampling technique responsible for the low populations recorded?
Although information on the occurrence of nematodes
in irrigation water has been presented, information was
usually not given on the methods of collection and extrac
tion. Since high nematode populations have been reported
by Faulkner and Bolander (7,8), a modification of their
sampling technique was used in this study.
1. Optimum sample size
To determine an optimum sample size 1, 2, 4, 7, 10,
15, 20, and 25 gallon water samples were taken with the
adjustable sampling hose and gas driven centrifugal pump.
Five replications of each volume were combined to maxe
each reading, and the procedure was repeated ten times.
Mean counts were recorded on each sample size (Figure 8),
The mean number of nematodes varied directly with tne
sample size. The one gallon sample size had the lowest
mean number of nematodes, and the twenty-five gallon had
the highest; however, the fifteen gallon sample size had
a lower mean number than the ten gallon sample. The average
number of nematodes for each reading among tne various
sample sizes and the variation within the samples are I—I 1 2 4 7 10 Sample size/gallons Figure 8. The mean number of nematodes per reading among the various sample S1ZG S • (Five subsamples of each volume were combined to make one reading and this procedure was repeated ten times)
to o given in Table 1. The 1, 2, 4, and 7 gallon sample sizes
showed a variation greater than 50% from the means of each
sample size, while the 10, 15, 20, and 25 gallon sizes
varied less than 504, The 10 gallon sample size showed
the least amount or variation among the sample sizes.
These results indicate that the larger sample sizes show
less variation within the samples. Although the number
of nematodes varied directly with the sample size, a
sample size giving the greatest number of nematodes per
volume of water was selected as an indication of optimum
sampling efficiency. To select the most effective sampling
size for use in this study, the number of nematodes per
gallon of water in each sample size was calculated
(Figure 9). The number of nematodes per gallon of water
fluctuated with sample size. The 10 gallon sample size
had the highest number of nematodes per gallon water
and the 25 gallon size the lowest. Mean counts varied
inversely from the 10 gallon sample size to the 25 gallon
size. A drop in sampling efficiency appeared to occur
between the 10 and 25 gallon sample sizes. A supposition
proposed at this point was that a loss of nematodes through
the sieves might be occurring in the 15, 20, and 25 gallon
sizes due to the increased pumping time required to take
these samples. My data do not conform with the results reported by
Faulkner and Bolander (1965). Although only 1, 2, 3, 5,
and 7 gallon sample sizes were tested, they reported that
the number of nematodes extracted per gallon water varied. Table 1. The mean number of nematodes per samnle size and the variation within sample sizes P ™eVsamD5faSe?h?^^ X °lume we« combined to make one sample and this procedure was replicated ten times)
Sample size/gallons Mean Variation 1 2.2 1.99
2 3.2 2.62
4 9.7 6.86
7 13.9 8.72
10 26.9 9.58
15 26.5 12.40
20 29.8 13.20
25 34.3 16.10 .8 . G O >-* 7 cd W)
Sample size/gallons Figure 9. The mean number of nematodes per gallon water among the various sample sizes. (Each volume consisted of 50 samples)
ro U) 24 inversely with the sample size. High populations were recorded in the 1 and 2 gallon sample sizes and low populations in the 7 gallon size. Populations of nematodes reported by Faulkner ano. Bolander were 30—80 times greater than those oi this study. Some reasons for discord between the two studies might be due to:
(1) The number of nematodes in the water system.
(2) The difference in sampling techniques and procedures.
(3) The variation in water flow.
(4) The size and types of nematodes in the water system.
(5) The source of water entering the system.
Since both studies represented distinctly different study areas and populations, no conclusions of optimum sample size for all conditions could be formulated at this time.
The 10 gallon sample size was used during the rest of the study because: (1) it recorded the highest population of nematodes per gallon of water; (2) it yielaed a large
enough population to permit accurate counting; and (3) it
showed the lowest percentage of variation among the sample
sizes.
2. Estimates of vertical distribution pattern
Information on the vertical distribution pattern of
nematodes is essential for making estimates of population
densities and for studying seasonal changes in population
levels. V attribution of nematodes in the aqueduct To estimate the distiibutx a vertical distribution study was conducted. A sampling
site, Pete Miller Road in the North San Joaquin Division, was selected on a straight section of the aqueduct. Water
samples were taken at 5 foot intervals from bank to bank
and from surface to bottom. Five replications of each
sample were combined to make each, reading. Since individual
readings indicated mixed nematode populations within the
aqueduct, the readings at each sampling level were combined
to determine whether any difference occurred between sampling
depths (Figure 10). A sampling depth of 17.5 feet from
the water surface had the highest mean number of nematodes
and the sampling depth closest to the bottom of the aqueduct
had the lowest. Mixed patterns of nematode populations
indicated a random distribution of nematodes within the
canal. This reaffirms an earlier report that nematodes
tend to be randomly distributed in a canal and there is
little tendency for nematodes to settle out in flowing water.
3. Estimates of horizontal distribution pattern
The California Aqueduct is not a continuous flow
system but is regulated by a series of gates and control
structures. The flow of water in the aqueduct is regulated
to meet the needs of the consumers. During periods of low
water usage water flow in the aqueduct is negligible.
Figure 11 gives the water flow pattern for the North
San Joaquin Division and the San Luis Division. In 1970,
the flow pattern in the North San Joaquin Division during
the months from June through part of SeptemocL 24
12.5' 17.5' 22.5 27.5 Sampling depth Figure 10. The mean number of nematodes per reading at various sampling depths. (Five subsamples were combined to make one reading and this procedure was repeated at five foot intervals from bank to bank)
ro
hO Flow volume varied from a high of 2900 acre feet flow per day to zero flow during these months. The flow pattern in the San Luis Division showed a small amount of variation in flow volume during the months of July and August. A high flow volume was recorded during the first week in
June, but by the last week in August the volume had declined
Water must be pumped from O'Neill Forebay and/or the
San Luis Reservoir into the California Aqueduct in the
San Luis Division when demands for water in this division are greater than the water flow from the North San Joaquin
Division. The differences in water regulation within the
divisions may affect the distribution of nematodes along
the study area.
To determine the distribution of nematodes in the
California Aqueduct along the North San Joaquin Division
and the San Luis Division, a horizontal distribution study
was conducted. Each division was divided into a north
and south sampling section (Figures 12,13). Thirteen
sampling sites were selected along the sampling area in
each division. Fifty 10 gallon samples were taken weekly
at a sampling site in each sampling section (Tables 2,3).
Sampling began on July 4th and ended on September 12, 1970,
for a total of 11 sampling periods. The results of the
horizontal distribution patterns in the North San Joaquin
Division are shown in Figure 14. Population peaks were
recorded during the 5th and 10th sampling periods. The 4--U -nor-th and south sections par- population patterns m the n nf the sampling periods. alleled each other during most
30
San Luis Reservoir O'Neill Forebay
NORTH SECTION
CALIFORNIA AQUEDUCT
SOUTH SECTION
0_ Kettleman City
Figure 13. A map _ of the ^^^g^plin^sites. ian Luis Division showing the vario nortJa^south^ecU^o? ?? ^ and the sampling periods. ' ciuin Division
I, North San Joaquin Division Sampling Periods
A. North Section
1. 6.83 miles* 6s IX
2. Hanson Road 1} 5? 7} 8
3. Hwy 15 crossing 3, 10
4. 25.71 miles* 2, 4, 9
B. South Section
5. Hansen Road 5
6. Niels Hansen Road 6
7. Simon Newman Road 11
8. May Road 10
9. Poverty Flat Road 4
10. McDowel l Road 8
11. Pete Miller Road 1> 0
12. Sullivan Road 7
13. Cottonwood Road 2, 3
* Indicates miles from Delta Pumping Plant. Table 3. The Location of the sampling sites in the north and south sections of the San Luis Division and the sampling periods. uue
I. San Luis Division Sampling Periods
A. North Section
1. Billie Wright Road 1, 4, H
2. Pioneer Road 6, 8
3. Creek Road 7, 10
4. Poleline Road 5
5. Lincoln Avenue 2
6. Dinuba Avenue 3, 9
B. South Section
7. San Diego Avenue 1
8. Parkhurst Avenue 11
9. Jeffrey Avenue 10
10. Yuba Avenue 2, 6
11. 0 &M Bridge 5> 7
12. 30th Avenue 4 3, 8, 9 13. Quail Avenue north section south section
5 6 7 Sampling periods
Figure 1-4. The mean number of nematodes per gallon of water extracted at weekly intervals in the north and south section of the North San Joaquin Division (Each reading consisted of 50 samples)
o u Populations recorded in the north section were higher in all sampling periods than in the south section. The differences in the population patterns during the sampling periods may be due to the variation in water flow in the
North San Joaquin Division during the sampling periods.
Differences in water regulation within the aqueduct may
account for the lower population pattern in the south
section. Lower populations in the south section indicate
some settling of nematodes might have occurred along the
study area.
Figure 15 gives the results of the horizontal distri
bution pattern in the San Luis Division. The data in
Figure 15 indicate an overlapping population pattern
between the north and south sections. Population peaks
were recorded during the 2nd, 6th, 7th, and 10th sampling
periods. Although population peaks fluctuated during the
sampling periods, both sections showed similar populatio
patterns. The fluctuation in the population patterns
between the north and south sections may be due t
ences in water flow between the North San Joaquin Division
and th e San Luis Division. As seen in Figure 11, low
water flow in the North San Joaquin Division would
necessitate that water be pumped from O'Neill Forebay^
and/or the San Luis Reservoir into the San ^is Divisi
to meet water requirements in the San Luis Division.
These other sources of water and the variation m
flow within the San Luis Division may account for t e
fluctuations that occurred during the sampling perio . north, section south section
i % » \ \ t \
5 t
4 i
3 I
• - 14 . 0Z a.
.1 i
10 1 8 Sampling periods Figure 15. The mean number of nematodes per gallon of water extracted weekly intervals in the north and south section of the San Luis Division. (Each reading consisted of 50 samples) 36 Since differences in population patterns occurred in the North San Joaquin Division and the San Luis Division, the data in the north and south, sections of each division were combined to compare population patterns for each division (Figure 16). Populations were higher in all sampling periods in the North San Joaquin Division than in the San Luis Division, except during the second sampling period. Population patterns were approximately parallel to each other during most of the sampling periods. The fact that water flow in the North San Joaquin is independent of water flow in the San Luis Division may account for the variation in population patterns between the two divisions. The lower population pattern in the San Luis
Division may be due to settling of nematodes oetween the
North San Joaquin Division and the San Lui.s Division.
Settling of nematodes may have occurred in O'Neill Forebay,
which separates the North San Joaquin Division from the
San Luis Division, or during periods of negligible water
flow in the divisions.
4. Estimates of total population Estimates were made on the total number of nematodes
tarried by the North San Joaquin Division and the San Luis
Division. Flow data obtained from the Nortn San Joaqui
Division and the San Luis Division Headquarters were used
to calculate the number of nematodes per day carried past j. . . Pumping time in the divi- a given point in each division,, -rflno-ed from 8 hours of sions during the sampling peri o The data in pumping per day to continuous pi P North San Joaquin Division San Luis Division
3
2
5 6 7 10 ] Sampling periods Figure 16. The mean number of nematodes per gallon of water extracted from the North San Joaquin Division and the San Joaquin Division. (Each reading consisted of 100 samples) Figure 17 indicate a higher population of nematodes per gay can be found in the North San Joaquin Division during all sampling periods except between the 1st and 2nd sampling periods. Population peaks were recorded during the 6th and the 10th sampling periods in the North San Joaquin
Division and during the 2nd, 6th, and 9th sampling periods ill the San Luis Division, and these follow the same general trend as the horizontal distribution study. Populations ranged from approximately 61 million nematodes per day to 300 million during the sampling period. The estimated total population pattern in the North San Joaquin and the
San Luis Divisions corresponds to the water flow patterns in these divisions during the sampling periods. As seen in Figure 11, the water flow pattern in the North San
Joaquin Division is lower than the flow pattern in the
San Luis Division during most of July, but then increases during the months of August and September. Peak flow periods can be seen during the first part of August and
September. The techniques used in this study will not detect
eggs and inactive forms of nematodes present in t
system; therefore, these are conservative estimates based
on active forms only.
5. Analysis of water samples Nematodes are important in such sectors of our society
as soil science, agronomy, plant pathology, fresh w
biology, economic entomology, drinking water 45 O North San Joaquin Division San Luis Division °? 400 o •H 3 350 e
CD 300 53
SP j 250 CFL QJ "g 200 4-1 'S CCj / X I 150
Sampling periods Figure 17. Estimated number of nematodes per day passing the various sampling sites during the sampling periods.
GJ o pesticide work and plant protection activities, to name a few.
The presence of nematodes in irrigation water is not a problem per se. In fact, many types of nematodes have been found to be beneficial in agricultural practices.
In 1929, Cobb reported two species of the genus Dorylaimus attacking the eggs of mites in decaying Narcissus bulbs.
Setae of oligochaets in the intestine of Dorylaimus regius was observed by Steiner in 1924. Linford and Oliveira in
1937 reported what they believed to be ten species of
Dorylaimus, one of Actinolaimus, and two of Discolaimus
feeding on other nematodes. In 1955, DuCharme suggested
that the presence of Radopholus simllis in the water table
in a Florida citrus grove may not be an important factor
in the spread of burrowing nematodes because of the presence
of Monoch id like predaceous nematodes which feed on other
nematodes.
Non-plant, parasitic nematodes present in the water
samples consisted of members of the genera Dorylaimus,
Mononchus, Aphelenchoides, Monohystera, M^o^orylaimu_s,
and Rhabditis. The agriculturalist is mainly concerned with the
presence of plant-parasitic nematodes in irrigation water
and the spread of these pests into non-infested agricultural
land. Examination of the water samples collected from the
California Aqueduct revealed the presence of ^J^^rhynchus
a genus of plant-parasitic nematodes. The genus Tylen chorhynchus is distributed world-wide although the known distribution of many species is very restricted. Represen tatives of the genus occur in most soil types and are often very numerous. The exact role this genus plays in plant disease has not been fully established. Many species are scattered throughout California, while some are limited
in distribution. Members of this genus are known to feed
on cotton, beans, tobacco, potato, grasses and many other
crops. Although the genus Tylenchorhynchus is found in
almost all soil types, it does not normally occur in
aquatic habitats (irrigation canals, rivers, streams).
The mode of entry of this genus into the aqueduct is not
known at this time. Possible means of entry into tne
California Aqueduct may be:
(1) The waterways of the Delta farmlands through the Delta
pumping plant. (2) Flood water entering the aqueduct through special
channels. (3) Large quantities of soil and small pieces of plant
debris blown from fields into the aqueduct. The overall role of Tylenchorhynchus as an economic
plant pest in California has not been fully evaluated. 42
CONCLUSION
Nematode populations of approximately 61 million to
300 million individuals passing a given point per day in the study area are below those reported by other workers investigating similar habitats. Conservative estimates of the number of nematodes collected from the study area
suggest that a naturally lower population of nematodes
occurs in this section of the California Aqueduct.
Increases in nematodes per sample size suggest that
the extraction techniques employed in the smaller sample
sizes were at least as efficient as those used by other
workers. Vertical distribution patterns exhibited by the
nematodes in the study area were similar to those described
by other workers, and studies revealed that in most cases
nematodes tend to be randomly distributed in flowing water.
In this study, apparent changes in horizontal distri
bution patterns must be interpreted as the result of p P
tion changes in the aqueduct due to the differences in water
regulation in the North San Joaquin Division and the San
Luis Division. Also, in some instances the changes may
be due to the settling of nematodes when water movement
is negligible.
The detection of one genus of plant-parasitic nema o
does not constitute an economic problem at this time but
provides evidence that certain types of plant-parasitic
nematodes may be transported by this water system though it is not a continuous flow system. Because of the enigmatic nature of the water habitat and the small size of its inhabitants, little is known about the inter relationship between environmental conditions and nematode populations.
Much more research will be required to achieve an even partially complete understanding of the variation of nematode populations occurring in irrigation water, and to assess the economic importance of these individuals in agricultural practices. 44 LITERATURE CITED
1. Chang S.L. J.H. Austin, H.W. Poston, and R.L. Woodward. iJOJ. Occurrence o£ a nematode worm In a city water supply. J. Amer. Wat. Wks. Ass. 51:671-676.
2. Chang, S.L. , R .L. Woodward, and P.W. Kabler. 1960. Survey of freeliving nematodes and amoebas in municipal supplies. J. Amer. Wat. Wks. Ass. 53:613-618.
3. Christie, J.R. and V.G. Perry. 1951. Removing nematodes from soil. Proc. helminthol. Soc. Wash. 18:106-108.
4. Cobb, N.A. 1929. Nemas of the genus Dorylaimus attacking the eggs of mites. J. Parasitology 15:284.
5. Courtney, W.D. , D. Polley, and V.L. Miller. 1955. TAF, an improved fixative in nematode technique. PI. Dis. Rep. 39:570-571.
6. DuCharme, E.P. 1955. Sub-soil drainage as a factor in the spread of the burrowing nematode. Proc. Fla. State Hort. Soc. 68:29-31.
7. Faulkner, L.R., and W.J. Bolander. 1967. Occurrence of large nematode populations in irrigation canals of south central Washington. Nematologica 12:591-600.
8. Faulkner, L.R. and W.J. Bolander. 1970. Acquisition and distribution of nematodes in irrigation water ways of the Columbia Basin in eastern Washington. J. of Nematology 2:362-367.
9. Faulkner, L.R. and W.J. Bolander. 1970. Agriculturally- polluted irrigation water as a source of piant- parasitic nematode infestation. J. of Nematology 2:368-374. 10. Fisher, K.D. 1968. Population patterns of nematodes in Lake Champlain. Nematologica 14:1-19.
11 Cadea E 1961. The nematode communities inhabiting 11. Gadea.JE. ^^ M otopes< Nematologica 7:15 (Abstr.).
Gad ^t^af&a Ifk, S-^ace- fields in Spain. Nematologica /:1D. io r ac r H 1923 The eelworm disease; a menace to 13. Godfrey, G.H. ^zo. me ^ 297 8 pp> alfalfa in America. U.S.D.A. Lire. z*/. FF G°°driCh' Hechler, and D,P. Taylor. 1968. Mononchoides changi n. sp. and M. bollingeri n. treatment, plant. Nematologica T4:I3"I3JI,"—
Heald, C.M. , and A.W. Johnson. 1969. Survival and mfectivity of nematodes after passing through an overhead sprinkler irrigation system. J. of Neonatology 1:290 (Abstr.).
Linford, M.B. and J.M. Oliveira. 1937. The feeding of hollow-spear nematodes on other nematodes. Science 85:295-297.
Petherbridge, F.R. and F.G.W. Jones. 1944. Beet eelworm (Heterodera schachtii Schmidt) in East Anglia. Ann. AppIT Biology 31:320-332.
Steiner, G. 1924. On some plant parasitic nemas and related forms. J. Agric. Res. 28:1062-1064.
Taylor, A.L. 1967. Introduction to research on plant nematology. An F.A.O. guide to the study and control of plant-parasitic nematodes. Rome: Food and Agriculture Organization of the United Nations 133 pp.
Thorne, G. 1941. Control of sugar beet nematode by crop rotation. Fmrs' Bull. U.S.D.A. No.1514.