The Differentiation of Fireblight Resistant Seedlings within Progenies of Interspecific Crosses of Pear

61 Pages·8.155 MB·English

by  Carpenter, Theodore Richard

PURDUE UNIVERSITY
THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION
Theodore Richard Carpenter
BY
ENTITLED DIFFERENTIATION OF FIFEBLIGHT RESISTANT SEED-
LINGS WITHIN PROGENIES OF INTERSPECIFIC CROSSES OF PEAR
COMPLIES WITH THE UNIVERSITY REGULATIONS ON GRADUATION THESES
AND IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS
FOR THE DEGREE OF
Doctor of Philosophy
Professor in Charge of Thesis
H eap of S chool or D epartment
TO THE LIBRARIAN:
THIS THESIS IS NOT TO BE REGARDED AS CONFIDENTIAL
GRAD. SCHOOL FORM O

THE DIFFERENTIATION OF FI REBLIGHT RESISTANT SEEDLINGS WITHIN
PROGENIES OF INTERSPECIFIC CROSSES OF PEAR
A Thesis
Subm itted to the Faculty
of
Purdue U niversity
by
Theodore Richard Carpenter
In P a rtia l F ulfillm ent of the
Requirements fo r the Degree
of
Doctor of Philosophy
January, 1951
ProQuest Number: 27714180
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ACaCNOWLEDQVENTS
G rateful acknowledgment is made to Dr. J. R. Shay, Department
of Botany and P lant Pathology, Purdue U niversity, fo r his assistance
and guidance in the preparation of th is th esis and in the experim ental
studies which preceded it* The w riter wishes to express his appreci­
ation to Dr. G. A. G ries, Department of Botany and Plant Pathology, Pur­
due U niversity, fo r advice and assistance in the n u tritio n studies and
Professor S. R. M iles, S tation S ta tistic ia n , A gricultural Experiment
S tation, Purdue U niversity, fo r advice in the s ta tis tic a l analyses of
the data* I t is also the wish of the w riter to acknowledge the co­
operation and m aterials so w illingly furnished by Dr. L. F. Bough,
Rutgers U niversity, form erly of the U niversity of Illin o is , and Dr. C*
J. B irkeland. U niversity of Illin o is*
TABLE OE CONTENTS
Page
ABSTRACT
INTRODUCTION...................................................................................... 1
A REVIEW OF THE LITERATURE.............................................................................................. 2
MATERIALS.................................................................................................................................... 3
METHODS ......................................................................................................................................... 7
RESULTS......................................................................................................................................... 17
Growth Stage at Which R esistance is Expressed by Young
Seedlings ................................................................................ 17
Greenhouse Seedling Vs. F irst Year Nursery Inoculations 19
Temperature E ffects on Growth and Disease Ratings . . . . 34
E ffect of N utrition on Growth and Disease Ratings . . . . 39
Condition of Growth a Factor in Disease Rating * . . • • 39
Leaf Spot on Three-Year-Old Seedlings in the 1950 Nursery 43
DISCUSSION ................................... 45
SUMMARY......................................................................................................................................... 47
LITERATURE CITED................................................................. 49
LIST OF TABLES AND FIGURES
L ist of Tables
Page
Table
1* V ariation of n u trien t sa lts used in n u tritio n stu d ies.
Greenhouse, 1950. L afayette, Indiana • • • • 9
2. The effect of age on disease ratin g of pear seedlings
follow ing in itia l inoculation w ith E. amylovora.
L afayette, Indiana . . . . . . 18
3. Summary of the performance of seedlings of u ssu rien sis
follow ing inoculation w ith E* amylovora at 18-24-leaf
stage and at 2 and 3 y e a r s ....................................................................... 20
4. Summary of the performance of seedlings of P. ussuri ensis
follow ing inoculations with_E. emylovora at 1, 2 and 3
years of age. L afayette, In d ia n a .................................................... . 21
5* Disease indexes of seedling lo ts inoculated w ith EL
amylovora. One lo t in itia lly inoculated at the 18-24-
leaf stage in the 1948 greenhouse, and one lo t in itia lly
inoculated at a la te r growth stage in the nursery.
L afayette, Indiana . . . . . . . . . 23
6, Chi-square te sts of the reactions of seedling lo ts inocu­
lated w ith E. amylovora. One lo t in itia lly inoculated
at the 18-24-leaf stage in the 1948 greenhouse and one lo t
in itia lly inoculated at a la te r growth stage in the nur­
sery. L afayette, Ind iana.. . . . . . . . . 24
7* Summary of the performance of re sista n t Pyrus seedlings
follow ing inoculation with_E. amylovora at the 18-26-
leaf stage in the greenhouse, 1949 and in the nursery,
1950. L afayette, Indiana ................................... 26
8* Binomial comparisons of established infection diseases
(exclusive of 0 and 4) w ith corresponding disease in­
dexes attain ed the follow ing year for seedlings in itia lly
inoculated at the 18-24-le a f stage in the 1948 green­
house. L afayette, Indiana . . . . . » 28
9. Binomial comparisons of 1949 established in fectio n classes
(exclusive of 0 and 4) w ith corresponding disease indexes
attained in 1950 fo r seedlings in itia lly inoculated at
the 18-26-leaf stage in the 1949 greenhouse. L afayette,
Indiana . . . . . . . . . ....................................................................... 29
Table Page
10* Binomial comparisons of established in fectio n classes
(exclusive of 0 and 4) w ith corresponding disease in ­
dexes attained the follow ing year fo r seedlings
in itia lly inoculated in the 1948 nursery. L afayette,
Indiana * .................................................................................................................... 31
11* The effect of cool and warm minimum greenhouse tem perature
on disease ratin gs of open-pollinated Ming seedlings
follow ing inoculation w ith JE. amylovora in the 18-24-
le af stage* L afayette, Indiana * . ............................................. 35
12. The effect of tem perature on growth and su scep tib ility to
fireb lig h t of Pyrus seedlings in the greenhouse, 1950.
L afayette, Indiana ................................................................................. 36
13* The effect of tem perature in predisposing Pyrus seedlings
to fireb lig h t development in the greenhouse, 1950*
L afayette, Indiana .................................................................. 38
14. Summary of the performance of Pyrus seedlings in sand cul­
ture follow ing inoculation w ith JE* amylovora in the green­
house, 1950* L afayette, Indiana .............................................* 40
15* Comparisons of early July w ith m id-July inoculation*
L afayette, Indiana ............................................................ 42
16* Leaf spot on three-year-old pear trees in the nursery in
October, 1950* L afayette, Indiana * . . . . . . ..................... 44
L ist of Figures
Figure Page
1* Temperature compartment used in the tem perature studies
showing the lig h tin g ,h eatin g and therm oswitch arrange­
ment .......................... 11
2* Infection classes dem onstrated by pear seedlings follow ­
ing inoculation w ith E. amylovora* A. Immune ( class 0)
dem onstrated by P. u ssu rien sis. 76 o.p. seedling. B.
M oderately re sista n t (class 2) dem onstrated by a Pal
Li o.p* seedling. C. Susceptible (class 4) dem onstrated
by a Pai Li o.p* seedling .............................. » 14
3* Equipment fo r spray-type inoculation. A* Atomizer* B*
C ut-off. C. Connection cu t-o ff. D. High pressure hose*
E* Reducing valve . . . . . . . . . . . . . ..................... e
18
ABSTRACT
F seedlings of pear crosses involving Pyrus u ssu rien sis Maxim,
and P* serotina Rehd. parentages were inoculated w ith Erw inia amylovora
(B u rrill) Winslow et a l., in succulent stem tip s w ith a hypodermic
needle, in early growth stages in the greenhouse and la te r growth stages
in f ir s t- , second- and th ird -y ear nurseries* The purpose was to ascer­
tain the rela tiv e efficiency of d iffere n tiatin g re sista n t and susceptible
segregates by inoculation at d ifferen t growth stages* There was no
appreciable resistance dem onstrated p rio r to the eig h t-leaf stage* A
higher percentage of susceptible seedlings was elim inated in the group
in itia lly inoculated in the greenhouse at the 18-24-leaf stage than from
sim ilar progenies in itia lly inoculated in the first-y e a r nursery* The
greenhouse inoculated seedlings dem onstrated a greater tendency to gain
in resistance and less tendency to sh ift to more susceptible in fectio n
classes during the second- and th ird -year inoculations than the seedlings
in itia lly inoculated in the first-y e a r nursery* In the th ird -y ear nur­
sery , there were many more holdover cankers among the seedlings o rig in al­
ly inoculated in the first-y e a r nursery than among the seedlings in itia l­
ly inoculated in the greenhouse. The most favorable tem perature found fo r
growth of the seedlings and elim ination of susceptible individuals was
78° to 80°F* Seedlings grown in sand at d ifferen t n u trien t sa lt concen­
tratio n s failed to dem onstrate sig n ifican t differences in resistan ce or
su scep tib ility at the differen t n u tritio n lev els.
C ultures of Jj. amylovora retained pathogenicity fo r longer
periods of time when stored under s te rile m ineral o il than when tran s­
ferred to fresh medium at two-week in terv als under aerobic conditions*
Highly satisfacto ry inoculum, was prepared by diffusing the
b acteria from diseased host parts which had been sectioned, placed in
w ater, and subjected to reduced pressure*
B acterial suspensions w ith carborundum added were sprayed on
seedling stem tip s at fifty pounds nitrogen gas pressure* This inocu­
la tio n method produced in fectio n resu lts comparable to the hypodermic
needle technique*