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"1 Ul-lW‘CtSity

 

This is to certify that the
thesis entitled

A STUDY OF TOLERANCE IN CARROTS (DAUCUS CAROTA L.)
TO NORTHERN ROOT-KNOT NEMATODE (MELOIDOGYNE HAPLA CHITWOOD)

 

 

presented by 9
Lawrence Wm. Yarger

has been accepted towards fulfillment
of the requirements for

M.S. Horticulture

degree in

(WW ~

J‘\\ lmmnpnmnun

 

 

Date 17 March 1980

 

0-7 639

OVERDUE .FlNES:
25¢ per day per item

RETURNING LIBRARY MATERIAL§:
Place in book netum to rem
charge from circulation recor

 

 

 

 

A STUDY OF TOLERANCE IN CARROTS
(DAUCUS CAROTA L.)

 

TO NORTHERN ROOT-KNOT NEMATODE
(MELOIDOGYNE HAPLA CHITWOOD)

 

By

Lawrence Wm. Yarger

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE
Department of Horticulture

1980

ABSTRACT

A STUDY OF TOLERANCE IN CARROT
(DAUCUS CAROTA L.)
T0 NORTHERN ROOT-KNOT NEMATODE
(MELOIDOGYNE HAPLA CHITWOOD)

 

 

1. Selection in Carrot for Tolerance to
Northern Root-knot Nematode

II. Influence of Carrot Cultivar on Marketability
as Affected by Northern Root-knot Nematode

By

Lawrence Wm. Yarger

Section I

A technique for screening carrot (Daucus carota L.) seedlings

 

under described greenhouse conditions was used to classify carrot culti-
vars and breeding lines for their response to northern root-knot nema-

tode (Meloidogyne hapla Chitwood). Breeding lines, 'MSU 872' and 'MSU

 

5988' exhibited tolerance; whereas 'MSU 9555', 'MSU 1394' and 'Gold
Pak 28' exhibited susceptibility to N, hapla,

These same accessions were also screened for their galling
response in muck soil under naturally infested field conditions.
'Spartan Classic' and 'MSU 872' were tolerant; whereas 'MSU l394' and

'MSU 9555' were susceptible to N, hapla.

Section II

 

Differences in responses of carrot (Daucus carota L.) cultivars

 

to northern root-knot nematode (Meloidogyne hapla Chitwood) were

 

Lawrence Nm. Yarger

demonstrated when grown in muck soil, under naturally infested field
conditions. Significant differences among carrot cultivars for galling,
forking and fasciculation were noted, but no significant difference was
noted for stubbing. A tolerance index (Ti) was calculated to compare
the overall response of the carrot cultivars to N, hapla, 'Spartan

Classic' was the most; whereas 'Danvers 126' was the least tolerant to

N, hapla.

LITERATURE REVIEW

Carrot breeding is a time-consuming process because of the bien-
nial habit of carrot, and breeding fbr nematode tolerance has been
unusually difficult and unsuccessful. The technique of screening seed-
lings in the greenhouse affords a rapid method of assaying carrots for
nematode tolerance. Carrot lines and cultivars have been screened and
tested under infested field conditions (3, 7), but nematode infestation
depends upon several factors including its reproductive potential,
host plant species and soil environment favorable for reproduction (1).
These factors cannot be readily controlled in the field by the
researcher. Moreover, nematodes are seldom, if ever distributed
uniformly over a field due to differences in soil, moisture, host plant
species, nematode migration and other biological aspects of the nema-
tode (6). Screening for nematode tolerance under these conditions can
lead to the selection of carrot roots appearing to be tolerant due to
absence of the nematodes. Unfortunately, this is commonly the case (6),
and most such selections are actually "escapes" which limit the pro-
gress of a selection program. The need for controlled inoculation and
incubation conditions is evident.

Due to the probable heterogeneity of carrot to nematode infesta-
tion and the lack of a truly "resistant" species, it is difficult to
determine a classification system for nematode tolerance. Susceptibi-

lity to N, hapla is based upon the ability of the nematode to grow and

reproduce in the host plant (6, 8). Most crops classified as "resis-
tant“ to nematode infestation are not truly resistant; i.e., they
tolerate the nematode attack, but symptoms such as gall formation are
still present (7, 10). These "tolerant" plants may function normally,
but such "tolerant" carrots would be commercially culled from the fresh
market. As a root crop for human consumption, carrots must be practi-
cally blemish-free to be marketable. Therefore, a tolerant cultivar
must utili2e a resistance mechanism which precludes visual damage to
the carrot root crop. Although there are reports of degrees of toler-
ance and resistance in carrots (3, 4, 7), there are no cultivars exhi-
biting "tolerance" or true "resistance" available to growers.

Crop species have been classified as being immune, resistant,
tolerant or susceptible to the root-knot nematode disease (2). These
are relative categories describing the host response in the D. M/
[1. 9.3.119. disease complex. Plants may display a number of resistance
responses. Generally, nematode larvae enter the roots of tolerant or
resistant plants as readily as they do susceptible plants (9). The
resistance reaction is triggered when the host/nematode relationship is
upset in some way. These responses may be expressed as larvae failing
to mature, larvae repelled or killed, extension of the development
cycle or an alteration of the sex ratio towards maleness (2).

The most common resistance response is hypersensitivity. This
describes the rapid death of the immediate host tissue cells soon after
nematode penetration, which results in either the rapid exit of the
nematode larvae or death of the larvae within the dead tissues (5).
There is no documented mechanism for resistance in carrots tolerant to

N, hapla, though there has been speculation that heterosis may play a

role in the tolerant response of hybrid carrot cultivars by "out-
growing" nematode attack and conditioning tolerance (7). The criterion
for rating nematode tolerance in the greenhouse seedling test was the
count of galls per plant. Fassuliotis reports (2) that galling alone
was not indicative of the degree of tolerance and could be misleading.
The purpose of assaying carrots for nematode tolerance, however, was

to obtain cultivars and breeding lines that would not develop hyper-
plastic and hypertrophic reactions, such as galling, that result in

unmarketable carrots.

LITERATURE CITED

1. Anonymous. 1970. Control of plant-parasitic nematodes. Princi-
ples of plant and animal pest control, Vol. 4, Publ. 1696.
National Academy of Sciences: Washington, D.C. 1972 pp.

2. Fassuliotis, G. 1979. Breeding for resistance. Pages 425-453
in F. Lamberti, and C. E. Taylor (eds.) Root-knot Nematodes
(Neliodogyne species). Academic Press, New York. 477 pp.

 

3. Hoser-Krause, J., and M. Brzeski. 1978. Breeding of carrots for
resistance to Meloidogyne hapla Chitw. Biuletyn Warzywniczy
XXII Instytut Warzywniczy, Skierniewice. pp. 172-174.

 

4. Janas, K. M. 1977. Poly phenols and inhibitors of indol-3-acetic
acid oxidase in carrots infested with northern root-knot
nematode. Acta Agrobotanica 30:13-31.

5. Milne, D. L., D. N. Boshoff, and P. W. W. Buchan. 1965. The
nature of resistance of Nicotiana repanda to the root-knot
nematode, Meloidogyne javanica. S. Afr. J. Agric. Sci., 8:
557-567.

 

 

6. Norton, D. C. 1978. Ecology of Plant-Parasitic Nematodes. John
Wiley and Sons: New York. 268 pp.

\1

Vrain, T. C., and L. R. Baker. 1980. Tolerance and resistance to
Meloidogyne hapla in carrot cultivars. Phytopath. (submitted).

 

8. Wallace, H. R. 1973. Nematode Ecology and Plant Disease. Crane,
Russak & Co., Inc.: New York. 228 pp.

9. Webster, J. M. 1975. Plant parasitic nematodes and host response.
Advances in Parasitology 13:225-250.

10. Wyatt, J. E., and G. Fassuliotis. 1979. Methods for screening
snap beans for resistance to root-knot nematodes. HortSci.
14:27-28.

DEDICATION

To my family and friends who have
given so much of themselves so I could pursue
this opportunity in my life;
And to the carrot growers of Michigan, for whom
I pray it benefits and without whom I

would not have been able to conduct this research

ACKNOWLEDGEMENTS

I would like to express thanks to all who have made the pursuit
of this degree a meaningful experience. Special thanks goes to my
guidance committee, Dr. Larry Baker, Dr. Hugh Price and Dr. George Bird
for the time and opportunities they have offered me along the lines of
research, extension and teaching. Thanks also to Nancy Glandon with
her greenhouse helpers, and to Ron Gnagey and Fred Richey and their
help at the research stations caring for my carrots.

I wish to extend special gratitude to Mansoor, Catorra, Michael,
Mary, Anand, NC, Neil, Muhammed, Marcia, Ibrahim, Noé and my friends in
the Hort Department, with whom I have learned and experienced much.

And, to my friend, Gene Lester, whose insights, acceptance and

encouragement has inspired me to do the same for others.

iii

TABLE OF CONTENTS

Page
LIST OF TABLES .......................... v
LIST OF FIGURES ......................... vii
SECTION I
SELECTION IN CARROT FOR TOLERANCE TO
NORTHERN ROOT-KNOT NEMATODE
Abstract ............................. 2
Materials and Methods ...................... 3
Results and Discussion ...................... 9
Literature Cited ......................... 13
SECTION II
INFLUENCE OF CARROT CULTIVAR ON MARKETABILITY
AS AFFECTED BY NORTHERN ROOT—KNOT NEMATODE
Abstract ............................. 17
Materials and Methods ...................... 18
Results ............................. 21
Discussion ............................ 27
Literature Cited ......................... 30

iv

Table

LIST OF TABLES

SECTION I

Carrot lines and cultivars assayed for their response
to M, hapla in a greenhouse seedling test at 25°C in
a sand:‘ muck medium .................

Comparison of steam-sterilized media for the induction
of nematode galls on carrot cultivar, Gold Pak 28

Classes used to characterize carrot lines and cultivars
for M, ha la attack under controlled greenhouse condi-
tions, in the seedling stage and in the field at
maturity .......................

Classification of carrot breeding lines and cultivars
tested in the greenhouse and field for tolerance to

M, hapla .......................

SECTION II

Carrot cultivars and breeding lines assayed for their
response to M, hapla in muck soil under naturally in—
fested field conditions ...............

Response of carrot cultivars and breeding lines grown
under muck field conditions, naturally infested with

M, hapla .......................

Forking of carrot cultivars grown under muck field con-
ditions, naturally infested with M, hapla ......

Stubbing of carrot cultivars grown under muck field
conditions, naturally infested with M, hapla .....

Galling of carrot cultivars grown under muck field con-
ditions, naturally infested with M, hapla ......

Fasciculation of carrot cultivars grown under muck
field conditions, naturally infested with M, hapla . .

Overall response of carrot cultivars grown under muck
field conditions, naturally infested with M, hapla . .

Page

10

19

20

23

24

25

26

LIST OF TABLES--Continued
Table Page
8. Correlation of responses of 9 carrot cultivars to

M, hapla, grown under naturally infested field con-
ditions ....................... 29

LIST OF FIGURES

Figure Page
SECTION I

1. The incidence of nematode galls on carrot seedling roots
as affected by the inoculum level ............. 7

vii

Readers:

The journal format which was utilized in this thesis meets the
requirements stipulated by the Horticulture Department and the Univer-
sity. The thesis body was separated into two sections. Section I was

prepared for publication in Plant Disease, and Section II for the

 

 

Journal of the American Society of Horticultural Science. Each section

follows the manuscript style adapted by the respective journal.

viii

SECTION I
SELECTION IN CARROT
FOR TOLERANCE TO
NORTHERN ROOT—KNOT NEMATODE

Selection in Carrot for Tolerance to
Northern Root-knot Nematode

L. W. Yarger and L. R. Baker,

Department of Horticulture,

Michigan State University,
East Lansing

ABSTRACT

A technique for assaying carrot (Daucus carota L.) seedlings under
described greenhouse conditions was used to classify 21 carrot cultivars
and breeding lines for their response to northern root-knot nematode
(Meloidogyne hapla Chitwood). Breeding lines, 'MSU 872' and 'MSU 5988'
were tolerant; whereas 'MSU 9555', 'MSU 1394' and 'Gold Pak 28' exhi-
bited susceptibility to M, ha la. The number of galls per root for

the two tolerant lines was -4; whereas the susceptible roots exhibited
20-41 galls.

The same 21 lines and cultivars were also assayed for their gall-
ing response in muck soil under naturally infested field conditions.
'Spartan Classic' and 'MSU 872' were tolerant; whereas 'MSU 1394' and
'MSU 9555' were susceptible to M, hapla. The two tolerant accessions
averaged 21.6 and 23.2% galled roots; whereas the two susceptible aver-
aged 44.8 and 48.8%.

 

 

Northern root-knot nematode (Meloidogyne hapla Chitwood) is a

 

serious pathogen of carrots (Daucus carota L.) in Michigan (2) where

 

6600 acres of carrots were harvested in 1979 (1). M, hapla_and Q,
gaggta form a complex host-parasite relationship characterized by a
number of symptoms including galling, forking, stubbing and fascicula-
tion of the roots; and yield reduction (6, 9, 10).

Carrot roots attain full length during the first 2-3 weeks of
growth (9, 14). Carrots are most susceptible to M, Mapla_during this
period. Obstacles to root elongation such as rocks, nondecomposed
organic material, compacted soil and soil insects can cause tap root

malformations (13, 14). Diseases caused by other pathogens can also

2

cause root malformations such as stubbing, forking and fasciculation
(6). Yield losses and plant mortality due to nematode damage are exten-
sive (6, 9). Moreover, nematode control by soil fumigation is costly
and may approximate $250-$500/acre on Michigan mucklands.

Such symptoms, caused by the D, ga_r_c_1_t_a_-M. h_a_p_l_a_ disease complex or
by the environment are definitely yield-limiting. To study this
complex system, controlled conditions are necessary to eliminate unde-
sirable environmental interactions. This is especially important to the
carrot breeder selecting for nematode tolerance based upon a straight
and marketable root shape. The object of this research was to develop a
seedling assay to evaluate carrots for their response to northern root-
knot nematode under controlled greenhouse conditions. By such a tech-
nique an array of carrot lines and cultivars could be classified for

their response to M, hapla infestation.

MATERIALS AND METHODS

Carrot breeding lines and cultivars with different root types
(Table 1) were assayed for nematode tolerance. The hybrid cultivars
and their parents were recently described (5); whereas the standard cvs.
were described previously (2). Six soil media were tested and com-
pared to determine an acceptible medium for nematode infestatiOn
(Table 2). A stream-sterilized mixture of muck and sand (1:1) resulted
in the induction of the most galls per plant, though not significantly
different from the sand medium. This medium supplied nutrients to the
emerging carrots and could be easily removed from the seedlings to

count the number of galls with minimal damage to the roots.

Table 1. Carrot lines and cultivars assayed for their response to M,
hapla in a greenhouse seedling test at 25°C in a sand: muck medium

 

 

 

 

Accession Source/Lot no. Root typea Top lengthb
Cultivars

Spartan Delux F] Crookham I L
Spartan Delite F1 Crookham I M
Spartan Fancy F1 Crookham I M
Spartan Premium F1 Crookham LN M
Spartan Classic F] Crookham ND M
Spartan Bonus 80 F1 Crookham D L
Danvers 126 Northrup King 0 L
Scarlet Nantes Northrup King N M
Gold Pak 28 Ferry Morse I M
Red Core Chantenay C6051 C L

Breeding lines

 

 

MSU 1394 75W338 I L
MSU 5986 71W33 I M
MSU 1302 75W92 I M
MSU 871 C5009 I S
MSU 6000 421013 ,I S
MSU 8549 75H2 IN S
MSU 5988 72W161 LN M
MSU 872 C534 LC M
MSU 1475 C5019 LC M
MSU 9555 78W190 CO L
MSU 9541 72W91 D L
aC Chantenay, L = long, 0 = Danvers, I = Imperator and

N Nantes root types (see Babb, et al. for description of root
types .

bS = short, M = medium and L = long top lengths.

Table 2. Comparison of steam-sterilized media for the induction
of nematode galls on carrot cultivar, Gold Pak 28

 

 

Soil medium Galls per planta

 

Sand: Muck (1:1) 19.1 a
Sand 12.6 ab
Muck 10.3 bc
Loam: Peat: Sgnd (1:1:1) 5.3 bc
Metro Mix 200 3.0 c
Vermiculite 0.3 c

 

aMeans in a column followed by the same letter are not significantly
different using Tukey's HSD test, P = 0.05.

bGrace Horticultural and Agricultural Products, W.R. Grace and Co.,
Cambridge, MA 02140.

Greenhouse evaluation. Nematodes were reared in the greenhouse

 

on tomato (Lycopersiton esculentum Mill.) and the eggs used for inoculum

 

were extracted with a 1.0% NaOCl solution (7). They were calibrated
and refrigerated (5°C) in a water suspension for up to six months and
used as needed for experimentation.

A concentration of 500 eggs/100 ml medium was used as inoculum
to produce galls on carrot seedlings for evaluation (Figure 1). The
number of galls produced was directly proportional to the number of eggs
added to the medium. Other screening techniques have utilized different
inoculum levels (11, 15). However, with 500 eggs/100 ml medium, the
number of galls per plant was such that the carrot roots could be eval-
uated and classified from susceptible to tolerant to nematode attack.

Seeds of each line or cultivar were individually sown into 2.5 x
2.5 x 12.5 cm cells of styrofoam 'Speedling Trays' (Speedling, Inc.,
Sun City, FL 33586). Each cell (seed) was inoculated with a suspension
of nematode eggs to approximate 370 eggs per seed. In the greenhouse
the trays were randomly arranged in a mist chamber with periodic over-
head misting every 30 min. The chamber was temperature controlled to
provide a constant soil temperature of 25°C.

The life cycle of M, Mapla_is approximately 45 days, but galls
can be detected as early as three weeks after infestation (10).
Accordingly, carrot roots were examined for galls four weeks after
inoculation. Each accession was classified for its response to nematode
attack by counting the number of galls per plant and arbitrarily
dividing them into classes from susceptible to resistant (Table 3).

The experimental design was completely randomized. Data were

subjected to statistical analysis to determine significant differences

 

 

20—

 

No. galls/plant

 

 

 

 

 

 

 

 

 

100 250 500

O 10 50
No. eggs/100 ml soil

 

 

Fig. 1. The incidence of nematode galls on carrot seedling
roots as affected by the inoculum level.
(Correlation coefficient = 0.99; P = 0.001.)

Table 3. Classes used to characterize carrot lines and cultivars for
M, hapla attack under controlled greenhouse conditions in the seedling

stage and in the field at maturity

 

 

 

 

 

 

Greenhouse
No. of galls/root Class
O Resistant
1-5 Tolerant
6-15 Tolerant-susceptible
16-25 Susceptible-tolerant
> 25 Susceptible
Field
% galled roots
O-lO Resistant
11-20 Resistant-tolerant
21-30 Tolerant
31-40 Tolerant-susceptible
41-50 Susceptible-tolerant
>50 Susceptible

 

in nematode response among carrot lines and cultivars.

Field evaluation. The same 21 carrot lines and cultivars were

 

also grown and evaluated under naturally infested field conditions in a
Houghton muck soil with a four year history of root-knot infestation
(Table 1). The carrots were seeded in May in rows 3 m long and 0.5 m
apart. After three weeks the seedlings were thinned to 36 plants/m.
Standard cultural practices were used for muck-grown carrots (3).

The carrot roots were harvested in September and examined to
determine the percent of roots with nematode galls. A sample of 25
roots was harvested from the center of each plot. Nematode infestation
was verified by soil assay and the presence of galls on the roots. The
experimental design was a Youden Square (16) with five replications,
utilized to minimize possible variation in the nematode population
throughout the testplot (8). The data were statistically analyzed and
the carrot lines and cultivars described in relation to their galling

response to M. hapla.

RESULTS AND DISCUSSION

- In the greenhouse evaluation, the more tolerant lines were 'MSU
872', 'MSU 5988', and 'MSU 1475 (Table 4). The response among inbred
breeding lines was great as evidenced by a range of 3 to 41 galls per
plant. A wide response among cultivars was also observed. The number
of galls per plant ranged from 6 to 28. The more tolerant cultivar was
'Spartan Classic' although the significance among cultivars was not
great. Noteably, the more susceptible cultivars were the standard
cultivars commonly used in carrot production.

The same array of carrot lines and cultivars was tested under M,

hapla infested field conditions (Table 4). The percentage of plants

10

Table 4. Classification of carrot breeding lines and cultivars tested
in the greenhouse and field for tolerance to M, hapla

 

 

 

 

 

 

 

Accession Greenhouse testa Field testa
No. galls % plants
per plant Rank Class galled Rank Class

Cultivars
Spartan Classic 6.2 a l T-S 21.6 a 1 T
Spartan Delux 6.6 a 2 T-S 28.0 a 5 T
Spartan Bonus 80 7.1 a 3 T-S 24.8 a 3 T
Spartan Delite 7.2 a 4 T-S 28.0 a 5 T
Scarlet Nantes 8.5 a 5 T-S 27.2 a 4 T
Spartan Fancy 8.7 a 6 T-S 24.8 a 3 T
Danvers 126 9.3 a 7 T-S 38.4 a 7 T-S
Red Core Chantenay 13.1 ab 8 T-S 37.6 a 6 T-S
Spartan Premium 20.6 bc 9 S-T 23.2 a 2 T
Gold Pak 28 27.9 c 10 S 28.0 a 5 T

Breeding lines
MSU 872 3.3 a l T 23.2 a l T
MSU 5988 4.3 a 2 T 28.8 abc 3 T
MSU 1475 5.0 a 3 T 28.8 abc 3 T
MSU 8549 6.2 a 4 T-S 31.2 abcd 4 T-S
MSU 1302 6.6 a 5 T-S 26.4 ab 2 T
MSU 5986 6.7 a 6 T-S 36.0 abcd 5 T-S
MSU 871 7.5 a 7 T-S 51.2 d 10 S
MSU 6000 9.3 a 8 T-S 44.0 abcd 7 S-T
MSU 9541 19.4 a 9 S-T 41.6 abcd 6 S-T
MSU 1394 20.3 a 10 S-T 44.8 bcd 8 S-T
MSU 9555 41.3 b 11 S 48.8 cd 9 S-T

 

aMeans in a column followed by the same letter are not significantly
different using Duncan's multiple range test, P = 0.05.

11

with galled roots within cultivars varied from 21.6 to 38.4%. Within
lines, the range was from 23.2 to 51.2%.

The carrot lines and cultivars were ranked for nematode tolerance
(Table 4). There was a significant correlation of field with greenhouse
test results among breeding lines (r = 0.63; P = 0.05). In each case,
MSU lines '872', '5988' and '1475' exhibited tolerance to root-knot
infestation; whereas '9555' and '1394' exhibited susceptibility. There
was no significant correlation between the results of the field and
greenhouse tests for the cultivars. This absence of significance might
be due to the major change in rank of 'Spartan Premium' and 'Gold Pak
28' (Table 4).

There appears to be an association of root type with nematode gall
formation and tolerance (Tables 1, 4). In the field experiment, carrots
with Nantes and Long Chantenay root types ('Spartan Classic', 'Spartan
Premium', 'Scarlet Nantes', 'MSU 8549', 'MSU 872' and 'MSU 1475')
exhibited tolerance. These same seven accessions in greenhouse tests
were tolerant of nematode galling, except for 'Spartan Premium'. In
both experiments, carrots with Danvers root types, except for 'Spartan
Bonus 80' exhibited susceptibility. 'Spartan Bonus 80', however, is a
three-way hybrid cross of (Long Chantenay x Imperator) x Danvers root
types (5). Thus, the Long Chantenay x Imperator maternal parent may
exhibit dominance over the susceptible Danvers paternal root type for
nematode tolerance.

Screening for nematode tolerance under naturally infested field
conditions often leads to the selection of non-diseased roots appearing
to be tolerant, but which are actually "escapes" from nematode infesta-

tion (8). Our greenhouse seedling test alleviates this and permits

12

rapid controlled screening and evaluation of carrots for root-knot
tolerance based on gall formation. Possibly, a carrot cultivar with
tolerance to M. M could be developed based on 'MSU 872', 'MSU 5988'
and 'MSU 1475'. However, carrots must be blemish-free to be acceptable
for fresh-market consumption. Accordingly, cultivars tolerant or
resistant to M, Mapla_must utilize a resistance mechanism which
precludes visual damage to the carrot root. Many more lines and culti-
vars should be screened to identify other accessions with tolerance that
could be used in carrot breeding programs. In future studies we propose
to study the relationship of other root-knot nematode disease symptoms

with tolerance in carrots.

LITERATURE CITED

13

10.

11.

12.

LITERATURE CITED

Agriculture Across Michigan. 1979. Michigan vegetable production
up 5 percent. Publ. Mich. Agric. Rep. Serv. Vol. 1 No. 24.

Anonymous. 1970. Estimated crop losses from plant-parasitic
nematodes in the United States. Special Publ. No. 1 Suppl. to
J. Nematol., Society of Nematologists, Committee on Crop
Losses. 4 pp.

Anonymous. 1978. Vegetable Production Recommendations. Ontario
Ministry Agric. and Food, Publ. 363. 72 pp.

Babb, M. F., J. E. Kraus, and R. Magruder. 1950. Synonomy of
orange-fleshed varieties of carrots. U.S. Dept. Agric. Circ.
833. Wash., D.C. 100 pp.

Baker, L. R. 1978. Spartan hybrid carrot series 1968-1976. Mich.
State Univ. Agric. Exp. Stn. Res. Rep. 359. 8 pp.

Crete, R. 1977. Diseases of carrots in Canada. Can. Dept. Agric.
Publ. 1615. 21 pp.

Hussey, R. S., and K. R. Barker. 1973. A comparison of methods
of collecting inocula of Meloidogyne spp., including a new
technique. Plant Dis. Rep. 57:1025-1028.

Norton, 0. C. 1978. Ecology of Plant-Parasitic Nematodes. John
Wiley and Sons: New York. 268 pp.

Slinger, L. A., and G. W. Bird. 1978. Ontogeny of Daucus carota
infected with Meloidogyne hapla. J. Nematol. 10:188-194.

 

 

Taylor, A. L., and J. N. Sasser. 1978. Biology, Identification
and Control of Root-knot Nematodes. NC States Univ. Graphics:
Raleigh. 111 pp.

Vrain, T. C., and L. R. Baker. 1980. Tolerance and resistance to
Meloidogyne hapla in carrot cultivars. Phytopath. (sub-
mitted).

 

Whitaker, T. W., A. F. Sherf, W. H. Lang, C. W. Nicklow, and J. D.
Radewald. 1970. Carrot production in the United States. U.S.
Dept. Agric. Handb. 375. Wash., D.C. 37 pp.

14

13.

14.

15.

16.

15

White, J. M. 1978. Soil preparation effects on compaction,
carrot yield and root characteristics in organic soil. J. Amer.
Soc. Hort. Sci. 103:433-435.

White, J. M., and J. 0. Strandberg. 1978. Early root growth of
carrots in organic soil. J. Amer. Soc. Hort. Sci. 103:344-347.

Wyatt, J. E., and G. Fassuliotis. 1979. Methods for screening
snap beans for resistance to root-knot nematodes. HortSci.
14:27-28.

Youden, W. J. 1940. Experimental designs to increase accuracy of
greenhouse studies. Contrib. Boyce Thompson Inst. 11:219-228.

SECTION II
INFLUENCE OF CARROT CULTIVAR ON MARKETABILITY
AS AFFECTED BY NORTHERN ROOT-KNOT NEMATODE

16

Influence of Carrot Cultivar on Marketability
as Affected by Northern Root-knot Nematode

L. W. Yarger and L. R. Baker
Department of Horticulture
Michigan State University,

East Lansing

Abstract. Differences in responses of carrot (Daucus carota L.) to
northern root-knot nematode (Meloidogyne hapla Chitwood) were demon-
strated when grown in muck soil, under naturally infested field condi-
tions. Significant differences among cultivars for galling, forking
and fasciculation were noted, but no significant difference was noted
for stubbing. A tolerance index (T1) was calculated by numerically
combining the effects of each response to compare the total reaction
of the carrot cultivars to M, hapla. 'Spartan Classic' was the most
tolerant; whereas 'Danvers 126 was the least tolerant to M, hapla.

 

Carrots are a major vegetable crop produced in the United States
and Michigan with a gross income of approximately $2,000/a for fresh
market carrots (4, 10). The marketability of fresh market carrots
depends heavily on the appearance of the root. Deep, loose soils with
good water-holding capacity are necessary for the development of long,
straight (marketable) roots (3).

Michigan ranks fifth in the production of carrots in the U.S.
(4), but due to intensive cropping and mono-cropping methods employed
by Michigan carrot growers, northern root-knot nematode has become a
serious pest. Moreover, approximately $100 million is spent annually
on nematode control in the U.S. (8). Disease symptoms typical of M,
Mapla_infection include reduced crop vigor and reduced marketable
yields due to forked, stubbed and fasciculated roots (3, 6, 8, 10).

However, these same symptoms can be induced by a number of other

17

18

pathogens (3, 10) and environmental factors (3, 7, 10, 11). The pre-
sence of nematode galls in conjunction with these symptoms is necessary
to verify M, Mapfla_infestation.

The purpose of this study was to evaluate the response of nine
,hybrid and open-pollinated carrot cultivars to M, hapla, and how their
response relates to the breeding and production of marketable roots

grown in naturally infested muck soil.

Materials and Methods
Carrot cultivars and breeding lines were grown with standard
cultural practices (1) in test plots at the Muck Research Station of
Michigan State University. The site was naturally infested with
northern root-knot nematode (M. h_agl_a_) as determined by soil assay and
the presence of nematode galls. The carrot roots were harvested and
evaluated for forking, galling, stubbing and fasciculation.

Symptomatology. Twenty-one breeding lines and cultivars were

 

sown in May, 1979 in rows 3 m long and 0.5 m apart (Table 1). After 3
weeks, the seedlings were thinned to 36 plants/m.

A sample of 25 roots was randomly harvested from the center of
each plot in September (approximately 120 days from seeding). The
percentage of roots damaged from forking and stubbing was recorded.
Severity of galling and fasciculation was rated on a scale of 1 to 5
(l = least damage; 5 = most damage) (Table 2). The experimental design
was a Youden Square (14) with five replications to minimize possible
variation in the nematode population throughout the test plot (5).

Tolerance evaluation. Nine cultivars of varied root types (Table

 

l) were grown and evaluated for their response to M, hapla under the

same field conditions as those in the symptomatology experiment. At

19

Table 1. Carrot cultivars and breeding lines assayed for their response
to M, hapla in muck soil under naturally infested field conditions

 

 

 

 

Accession Source/Lot no. Root typez

Cultivars
ySpartan Delite F] Crookham I
ySpartan Delux F1 Crookham I
ySpartan Fancy F1 Crookham I
ySpartan Bonus 80 F1 Crookham D
ySpartan Classic F1 Crookham ND
ySpartan Premium F1 Crookham LN
yDanvers 126 Northrup King 0
yScarlet Nantes Northrup King N
yGold Pak 28 Ferry Morse I

Red Core Chantenay C6051 C

Breedingiline

 

MSU 1394 75W338 I
MSU 5986 71W33 I
MSU 1302 75W92 I
MSU 871 C5009 I
MSU 6000 421013 I
MSU 8549 75H2 IN
MSU 5988 72W161 LN
MSU 872 C534 LC
MSU 1475 C5019 LC
MSU 9555 78W190 CD
MSU 9541 72W91 D

 

2C = Chantenay, L = long, 0 = Danvers, I = Imporator and N = Nantes
root types (see Babb, et al. for description of root types).

yCultivars evaluated in experiment 2.

Table 2.

20

muck field conditions, naturally infested with M, hapla.

Response of carrot cultivars and breeding lines grown under

 

 

 

 

 

Percent Percent Fascicu-

forked stubbed Gallingz lation
Accession roots roots severity severity
Cultivars
Scarlet Nantes 12.8 ay 13.6 by 1.2 ay 1.0 ay
Red Core Chantenay 20.8 b 40.0 e 3.2 d 2.2 b
Spartan Bonus 80 23.2 be 19.2 c 1.4 ab 1.4 ab
Spartan Classic 24.8 bcd 20.8 cd 1.2 a 1.0 a
Danvers 126 25.6 cd 40.0 e 2.4 cd 1.4 ab
Gold Pak 28 28.8 d 12.0 b 2.2 bc 1.4 ab
Spartan Premium 36.0 e 24.0 d 1.4 ab 1.4 ab
Spartan Delite 36.0 e 8.0 a 2.0 abc 1.6 ab
Spartan Delux 39.2 ef 24.0 d 2.0 abc 1.6 ab
Spartan Fancy 41.6 f 20.0 c 1.6 abc 1.2 a
Breeding lines
MSU 5988 23.2 ay 15.2 aby 1.4 ay 1.2 aby
MSU 872 24.8 a 23.2 c 1.6 ab 2.0 bcd
MSU 1475 27.2 ab 24.0 c 2.2 abcd 1.0 a
MSU 8549 30.4 bc 16.0 ab 2.0 abcd 2.0 bcd
MSU 1302 32.8 c 18.4 b 1.8 abc 1.4 abc
MSU 9555 33.6 c 46.4 e 2.2 abcd 2.4 de
MSU 6000 40.8 d 14.4 ab 3.0 d 3.2 e
MSU 871 40.8 d 32.8 d .2.6 bcd 1.2 ab
MSU 5986 46.4 e 13.6 a 1.8 abc 1.4 abc
MSU 9541 49.6 ef 36.0 d 2.4 abcd 2.4 de
MSU 1394 51.2 f 16.0 ab 2.8 cd 2.2 cd

 

ZRated subjectively on a scale of 1 (least damage) to 5 (most damage).

yMean separation within columns by Duncan's multiple range test, 5%

level.

21

harvest the percentage of roots galled, fasciculated, stubbed and
forked was noted. The severity of galling and fasciculation was subjec-
tively rated on a scale of l to 5 (1 = least damage; 5 = most damage).

A cumulative tolerance index, Ti’ was calculated to measure the
overall response to M. hapla as follows:

Ti = A9 + BS + C1, + Dh + ES + FS
where A9 = percent galled roots, BS = percent stubbed roots, Cf =
percent forked roots, Dh = percent fasciculated (hairy) roots, E5 =

galling severity and FS = fasciculation severity. Low index values
are indicative of a greater tolerance to M, hapla in contrast to high

values indicating susceptibility.

Results

Symptomatology. The results of this experiment were used as a

 

preliminary test to see if there were differences in severity of damage
among carrot cultivars and breeding lines due to M, hapla, Among
cultivars, 'Spartan Classic' and 'Scarlet Nantes' were the most
tolerant to galling with a severity rating of 1.2, though they were not
significantly different from the other 'Spartan' cultivars. Conversely,
'Red Core Chantenay', rated 3.2, was the most susceptible (Table 2).
'Scarlet Nantes' had the lowest percentage of forked roots with 12.8%,
while 'Spartan Fancy' had the highest with 41.6%. 'Spartan Delite'
responded with 8.0% stubbed roots; whereas 'Red Core Chantenay'
responded with 40.0%. Fasciculation severity ranged from 1.0 with
'Spartan Classic' and 'Scarlet Nantes' to 2.2 with 'Red Core Chantenay'

though accessions were not significantly different.

22

'MSU 5988' was most tolerant to galling with a severity rating of
1.4; whereas 'MSU 6000' wasmost susceptible with a rating of 3.0
(Table 2). 'MSU 5988' was also the most tolerant of forking with 23.2%
forked roots; whereas 'MSU 1394' was most susceptible with 51.2%.
'MSU 5986' had the fewest stubbed roots with 15.2%; whereas 'MSU 9555'
had the most with 46.5%. 'MSU 1475' was rated 1.0 for fasciculation
severity with 'MSU 6000' rated 3.2.

Tolerance evaluation. The responses of the nine cultivars in

 

this experiment to galling, forking, stubbing and fasciculation were
evaluated individually; then overall, in the form of a tolerance index
(11.).

Forking. Under the conditions of the experiment, forking
appeared to be prevalent in carrots with Imperator root types (Tables
1, 3). The cultivars were ranked in order of their response, ranging
from 14.8 to 51.2% forked roots (Table 3). 'Scarlet Nantes' was the
most and 'Spartan Delite' the least tolerant.

Stubbing. Percent stubbed roots ranged from 28.8 to 47.2%, but
there were no significant differences among cultivars (Table 4).

Galling. Percent galled roots ranged from 61.2 to 85.2%, with
'Danvers 126' and 'Spartan Fancy' exhibiting the least tolerance, but
with no significant differences among the other cultivars (Table 5).

Fasciculation. Percent fasciculated roots ranged from 14 to 50%

 

with 'Spartan Classic', 'Spartan Bonus' and 'Scarlet Nantes' exhibiting
the most tolerance (Table 6). The tolerant cultivars also demonstrated
the lowest ratings for severity of fasciculation.

Tolerance index (Ti)° The tolerance index demonstrated signifi-

 

cant differences among carrot cultivars. The hybrid, 'Spartan Classic'

23

Table 3. Forking of carrot cultivars grown under muck field conditions,
naturally infested with M, hapla

 

 

 

Cultivars Percent forked roots
Scarlet Nantes 14.8 a2
Spartan Classic 22.0 ab
Spartan Delux 28.8 bc
Spartan Premium 30.0 bc
Spartan Bonus 80 31.2 bc
Spartan Fancy 34.8 bc
Gold Pak 28 42.0 cd
Danvers 126 42.0 cd
Spartan Delite 51.2 d

 

zMean separation within column by Duncan's multiple range test, 5%
level.

24

Table 4. Stubbing of carrot cultivars grown under much field condi-
tions, naturally infested with M, hapla.

 

 

 

Cultivars Percent stubbed roots
Spartan Bonus 80 28.0 aZ
Spartan Classic 30.0 a
Spartan Delux 37.2 a
Spartan Premium 38.0 a
Spartan Delite 39.2 a
Scarlet Nantes 40.8 a
Danvers 126 44.0 a
Gold Pak 28 47.2 a

a

Spartan Fancy 47.2

 

zMean separation within column, by Duncan's multiple range test, 5%
level.

25

Table 5. Galling of carrot cultivars grown under much field conditions,
naturally infested with M, hapla.

 

 

 

Percent GallZ
Cultivars galled roots severity
Spartan Delux 61.2 ay 2.3
Spartan Premium 61.2 a 2.7
Spartan Bonus 80 64.0 a 2.7
Gold Pak 28 66.0 a 3.2
Spartan Classic 66.8 a 2.3
Scarlet Nantes 69.2 ab 2.8
Scarlet Delite 72.0 ab 2.8
Spartan Fancy 83.2 b 3.8
Danvers 126 85.2 b 4.0

 

ZRated subjectively on a scale of 1 (least damage) to 5 (most damage).

yMean separation, within column, by Duncan's multiple range test, 5%
level.

26

Table 6. Fasciculation of carrot cultivars grown under muck field
conditions, naturally infested with M, hapla.

 

 

 

Percent Fasciculationz

Cultivars fasciculated roots severity

/ Spartan Classic 14.0 ay 1.5
Spartan Bonus 80 18.8 a 2.2
Scarlet Nantes 20.8 a 2.2
Spartan Premium 25.2 ab 2.7
Spartan Delux 27.2 abc 2.7
Gold Pak 28 38.0 bcd 3.5
Spartan Delite 42.8 cd 3.8
Spartan Fancy 43.2 cd 3.3
Danvers 126 50.0 d 4.3

 

zRated on a scale of 1 (least damage) to 5 (most damage).

yMean separation, within column, by Duncan's multiple range test, 5%
level.

27

exhibited the most tolerance (least amount of damage) to M, hapla, and
'Danvers 126' exhibited the least (Table 7).

Correlation. Correlations among cultivars demonstrated an asso-

 

ciation of fasciculation with forking, stubbing and galling (Table 8).

There was, however, no correlation among forking, stubbing and galling.

Discussion

Data from the symptomatology experiment demonstrated differential
responses among carrot cultivars and breeding lines to M, hapla, In
previous field and greenhouse tests, these cultivars were uniform in
the galling response from M, hapla_infestation (13). In this experi-
ment, there was variation within cultivars for forking and fasciculation
as well as galling. Moreover, forking, stubbing and galling appeared
to be independent. This may indicate independent genetic control for
these responses, which contributes directly or indirectly to the overall
tolerance to M, hapla, A tolerance index (Ti) was used to measure the
overall response of each cultivar to M, hapla_and then to compare
differences among cultivars. Though differences were not great,
improvements might conceivably be made through successive generations
of selection for tolerance. From this information we can justify
further efforts toward breeding carrots for tolerance to northern

root-knot nematode.

28

Table 7. Overall response of carrot cultivars grown under muck field
conditions, naturally infested with M, hapla.

 

 

 

Tolerancez
Cultivars index (Ti)
Spartan Classic 136.6 ay
Spartan Bonus 80 146.9 ab
Scarlet Nantes 150.6 ab
Spartan Delux 159.4 abc
Spartan Premium 159.8 abc
Gold Pak 28 186.3 bcd
Spartan Delite 211.8 de
Spartan Fancy 215.5 de
Danvers 126 229.5 e

 

2T1 = Ag + 35 + Cf + Dh + ES + F5, where A9 = percent

galled roots,

B5 = percent stubbed roots, Cf = percent forked roots, Dh = percent

fasciculated (hairy) roots, ES

severity.

galling severity and FS = fasciculation

yMean separation within cultivars by Duncan's multiple range test,

5% level.

29

Table 8. Correlation of responses of 9 carrot cultivars to M, hapla,
grown under naturally infested field conditions

 

 

 

Forked Stubbed Galled Fasciculated Gall Fasciculation

Response (%) (%) (%) (%) severity severity
Forked

(%) 1.0 0.39”S 0.36NS O.80** 0.46"S O.84**
Stubbed

(%) 1.0 0.56NS O.78* O.81** 0.78*
Galled

(%) 1.0 0.74* O.88** 0.62N5
Fasciculated

(%) 1.0 O.81** O.97**
Gall

severity 1.0 0.75*
Fasciculation

severity 1.0

 

NS, *, ** Nonsignificant at 5% (NS) or significant at 5% (*) or 1% (**)
level.

LITERATURE CITED

3O

10.

ll.

12.

13.

LITERATURE CITED

Anonymous. 1978. Vegetable production recommendations. Ontario
Ministry Agr. and Food Publ. 363..

Babb, M. F., J. E. Kraus, and R. Magruder. 1950. Synonomy of
orange-fleshed varieties of carrots. U.S. Dept. Agr. Cir. 833.

Crete, R. 1977. Diseases of carrots in Canada. Can. Dept. Agr.
Publ. 1615.

Holko, M. 1979. Michigan agricultural statistics. Mich. Dept.
Agr., Mich. Agr. Rpt. Ser., Lansing.

Norton, D. C. 1978. Ecology of plant-parasitic nematodes. John
Wiley and Sons, New York.

Slinger, L. A. and G. W. Bird. 1978. Ontogeny of Daucus carota
infected with Meloidogyne hapla. J. Nematol. 10:188-194.

 

 

Strandberg, J. O. and J. M. White. 1979. Effect of soil compac-
tion on carrot roots. J. Amer. Soc. Hort. Sci. 104:344-349.

Taylor, A. L. and J. N. Sasser. 1978. Biology, identification
nad control of root-knot nematodes. NC State Univ. Graphics,
Raleigh.

Vrain, T. C. and L. R. Baker. 1980. Tolerance and resistance to
Meloidogyne hapla in carrot cultivars. Phytopath. (submitted).

 

Whitaker, T. W., A. F. Sherf, W. H. Lange, C. W. Nicklow, and J. D.
Radewald. 1970. Carrot production in the United States. U.S.
Dept. Agr. Handb. 375.

White, J. M. 1978. Soil preparation effects on compaction,
carrot yield and root characteristics in organic soil. J.
Amer. Soc. Hort. Sci. 103:433—435.

White, J. M. and J. O. Strandberg. 1978. Early root growth of
carrots in organic soil. J. Amer. Soc. Hort. Sci. 103:344-
347.

Yarger, L. W. and L. R. Baker. Selection of carrot (Daucus carota

 

L.) for tolerance to northern root-knot nematode (Meloidogyne
hapla Chitwood). Plant Disease (to be submitted).

 

31

32

14. Youden, W. J. 1940. Experimental designs to increase accuracy of
greenhouse studies. Contrib. Boyce Thompson Inst. 11:219-228.

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