Further studies on the relative susceptibility to citrus canker of different species and hybrids of the genus Citrus
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FURTHER STUDIES ON THE RELATIVE SUSCEPTIBILITY
TO CITRUS CANKER OF DIFFERENT SPECIES AND
HYBRIDS OF THE GENUS CITRUS, INCLUDING THE
WILD RELATIVES 1 .

By GEORGE L. PELTIER, formerly Plant Pathologist, Alabama Agridultural Experi-
ment Station, and Agent, Bureau of Plant Industry, United States Department of
Agriculture, and WILLIAM J. FREDERICH, formerly Assistant Pathologist, Bureau
of Plant Industry, United States Department of Agriculture

INTRODUCTION
The object of this paper is to present in a summarized form the results of the
writer's investigations, extending from 1917 to 1921, on the relative susceptibility
of citrus canker of a large number of different species, hybrids, and relatives of the
genus Citrus. During the progress of this investigation two detailed reports 2,3
have appeared. Since the last report was issued, new plants have been added
to the experiments, further numbers successfully infected and in some cases
continued observations have modified previous conclusions.
The reader is referred to the reports already published for the description of
the plants used, the location of the experiments, experimental methods em-
ployed and the detailed observations made. The complete data on each plant
included in the experiments during the course of the investigation are on file
in the Office of Crop Physiology and Breeding Investigations, Bureau of Plant
Industry, United States Department of Agriculture, Washington, D. C.

SUSCEPTIBILITY OF THE WILD RELATIVES OF THE GENUS
CITRUS
Repeated attempts to infect Melia azedarach L., in the field were unsuccessful.
Likewise, under greenhouse conditions, negative results were obtained with
Xanthoxylum bungei Planch., Xanthoxylum sp., Toddalia asiatica (L.) Kurz
and Glycosmis pentaphylla Correa. A few small infections on leaves were ob-
tained under greenhouse conditions with Claucena lansium (Lour.) Skeels, and
Chalcas exotica (L.) Millsp. However, these results could not be duplicated
in the field. . Casimiroa edulis Lay. & Lex., was the only plant of this group
that was successfully infected at wounds on the leaves, in the field and green-
house.
I Received for publication Feb. 16, 1924. Published with the approval of the Director of the Alabama
Agricultural Experiment Station. The paper is based on cooperative investigations between the Office of
Crop Physiology and Breeding Investigations, Bureau of Plant Industry, U. S. Department of Agricul-
ture and the Department of Plant Pathology, Alabama Agricultural Experiment Station.
2 PELTIER, G. L. SUSCEPTIBILITY AND RESISTANCE TO CITRUS-CANKER OF THE WILD RELATIVES,
CITRUS FRUITS, AND HYBRIDS OF THE GENUS CITRUS. [Preliminary paper.] Jour. Agr. Research 14: 337-
358, illus. 1918.
a -- and FREDERICH, W. J. RELATIVE SUSCEPTIBILITY TO CITRUS-CANKER OF DIFFERENT SPECIES AND
HYBRIDS OF THE GENUS CITRUS, INCLUDING THE WILD RELATIVES. Jour. Agr. Research 19: 339-362, illus.
1920.
Journal of Agricultural Research, Vol. XXVIII, No. 3
Washington, D. 0. Apr. 19 1924
Key No. Ala.-9


7425-24t


(227)





Journal of Agricultural Research


Vol. XXVIH, No. 3


Chaetospermum glutinosum (Blanco) Swingle was quite easily infected both in
the greenhouse and field in the absence of wounds. In fact, natural infection
from adjoining plants in the field frequently occurred. Judging from its suscep-
tibility under southern Alabama conditions, it is as susceptible as some of the
Citrus fruits. However, these plants can not grow in southern Alabama as they
are very easily killed by the winter temperatures generally prevailing in this region.
Of the remaining plants belonging to the subtribe Aeglinae, Balsamocitrus dawei
Stapf and Aeglopsis chevalieri Swingle remained free from infection after repeated
attempts to infect, while Aegle marmelos Correa, although infected at wounds
on the leaves in the greenhouse, remained nonsusceptible in the field.
Feronia limonia (Correa) Swingle was infected to some extent at wounds in
the greenhouse. No results were obtained in the field. In the case of Feroniella
lucida Swingle, however, positive results were obtained both in the greenhouse
and field.
On the plants in subtribe Lavanginae, two species, Triphasia trifolia (Burm.)
P. Wilson and Severinia buxifolia Ten. proved to be strictly nonsusceptible in
the field and greenhouse, while Paramignya monophylla Wight was easily in-
fected in the greenhouse. Likewise, plants of Hesperethusa crenulata (Roxb.)
Roem. were easily infected in the greenhouse and field through natural infection
from adjoining plants.
In the case of Severinia buxifolia it was repeatedly observed that the
leaves, petioles, and stems when punctured or wounded had the ability to form
cork tissues very rapidly. Owing to the nonsusceptibility of Severinia buxifolia
to citrus canker and the fact that it thrives under southern Alabama conditions,
its propagation as a hedge plant to replace Poncirus trifoliata (L.) Raf. should
be encouraged. Incidentally, it may prove suitable as a stock for some types
of Citrus fruits.
All plants of the subtribe Citrinae were successfully infected, but in varying de-
grees. Attempts to infect Citropsis schweinfurthii Swingle and M. Kellerman in
the field were unsuccessful, although small unruptured spots were produced at
wounds in the greenhouse. The two species of Atalantia have been rather
easily infected. Likewise, plants of Eremocitrus glauca (Lindl.) Swingle were
quite easily infected both in the greenhouse and field.
The three species and one variety of Microcitrus and Eremocitrus glauca
have proved susceptible enough under controlled conditions to be naturally
infected in their native habitat, if a source for infection was present. Both of
these genera are native of the east coast of Australia, and while citrus canker
has only been reported from the northern territory of Australia, should canker
be introduced at any time into the Citrus districts of Queensland,' there is a bare
possibility that citrus canker might be disseminated to the native growths of
Microcitrus and Eremocitrus.
Fortunella hindsii (Oliver) Swingle is rather susceptible; much more so than
any of the other three species of kumquats. While these were all successfully
infected in the greenhouse, only two, F. japonica (Thunb.) Swingle and F. Mar-
garita (Thunb.) Swingle gave positive results in the field.
In the spring of 1918, thirty 3-year-old trees of Fortunella margarita budded
on Poncirus trifoliata were planted in the isolation field. From the summer
of 1918 through the season of 1921, not a single canker spot was found on these
trees, notwithstanding the fact that various methods of inoculations were tried
and that during the active growing season they were at all times exposed to natural
infection. The kumquats, with the exception of F. hindsii are highly resistant
to Citrus canker and it is only under the most favorable field conditions and
through wounds on the leaves that they can be infected.
In conclusion, it might be stated that so far as the menace of citrus canker
to the Citrus industry in the United States is concerned, with the exception of
Poncirus trifoliata, none of the relatives of Citrus, native or introduced, discussed


228







Apr. 19, 14 CGankTer Susceptibility of Citrus Species and Hybrids 229

above are sufficiently susceptible to warrant further attention. However, it is
of scientific interest to know that Pseudomonas citri is not limited in its attack
to the genus Citrus but can produce, under certain conditions, infections on a
wide range of plants in the family Rutaceae to which Citrus belongs. In this
connection, the plant breeder is furnished facts which may assist him in develop-
ing hybrids of a commercial nature which are resistant to citrus canker.
SUSCEPTIBILITY OF CITRUS FRUITS
The difference in the susceptibility of the two forms of Citrus hystrix DC
has been consistent throughout the investigation. The round leaf form equals
grapefruit in its susceptibility to canker, while the pointed leaf form shows
some resistance to canker. Various forms of this obscure but large group should
be tested further in the Philippine Islands where it is native, and undoubtedly,
forms resistant to citrus canker will be found.
No changes were noted in the reaction of the citrons, lemons, and limes tested
in the greenhouse. None of these plants were used in the field, so that their
susceptibility to canker must be based on greenhouse results. While plants of
the Ichang lemon were testecdboth in the greenhouse and field, no changes have
occurred to modify previous reports.
All grapefruit plants tested are susceptible to citrus canker. Of the
pummelos, the Hirado Buntan and Siamese have shown some resistance in that
infection was almost wholly confined to the leaves with only an occasional spot
on a young, growing twig.
Of the sweet orange group, no variety or species stands out as resistant, al-
though they are not as susceptible as some of the other citrus fruits.
All of the plants belonging to the Citrus nobilis group show resistance to
canker. In the majority of instances, canker was limited to scattering spots on
the young leaves and on an occasional twig. The Cleopatra tangerine, which
appears to be an excellent stock for some types of Citrus might after further trials
be found suitable to replace the trifoliate orange as a stock.
As has been pointed out in a previous report, Tanaka * and Scott r have
shown that there are several distinct strains of Satsuma grown in southern
Alabama. The two most commonly found are the Owari and Ikeda. Scott
-describes them as follows:
The fruits of the Owari are flat, thin skinned, depressed at both the blossom andstem.ends, and practi-
*cally seedless, maturing in Alabama the latter part of October or first of November. The leaves are very
broad, particularly at the base, and the tree has an upright habit of growth.
The fruits of the Ikeda variety are not as flat as those of the Owari, are not depressed at either the stem
or blossom end, have a very coarse texture and a thick skin, and generally contain a few seeds. The season
of the Ikeda is three or four weeks later than that of the Owari variety. The leaves are narrow, and the
tree has a very spreading habit of growth.
From various sources reports of a difference in susceptibility between these
strains were received, and in order to determine if they varied in susceptibility the
following experiment was conducted.
During the early spring of 1918, thirty 3-year-old trees budded on Poncirus
trifoliata of the Owari strain and a like number of the Ikeda strain were planted
in the isolation field. As a control, thirty 3-year-old Duncan grapefruits budded
on Poncirus trifoliata were planted between the two rows of Satsumas. Obser-
vations were made as to the number of trees infected and the parts of the plants
attacked at intervals during the growing season over a period of three years.
During this time the number of trees did not remain the same in that a number
-died or were cut out to make room for the remainder to grow. At the conclusion
-of the test, only 13 of each kind of tree remained. Since these trees were always
surrounded by susceptible trees, natural infection was depended on entirely.
4 TANAKA, T. VARIETIES OF THE SATSUMA ORANGE GROUP IN JAPAN. U. S. Dept. Agr. Bur. Plant
Indus. Crop Physiol. and Breeding Inves. C. P. & B. I. Circ. 5, 10 p., illus. 1918.
5 ScoTT, L. B. VARIETIES OF THE SATSUMA ORANGE GROUP IN THE UNITED STATES. U. S. Dept. Agr.
.Bur. Plant Indus. Hort. and Pomol. Inves. H. & P. Circ. 1, 7 p., 1918.






230 Journal of Agricultural Research Vol. XXVIII, No. 3

At the conclusion of the investigation, no distinct difference in the suscepti-
bility of the two strains of Satsumas was apparent. While the number of Ikeda
trees infected earlier in the season was greater than the Owari, the reverse occurred
later in the season, so that more of the Owari trees were infected than Ikeda.
Further, infection was somewhat lighter on Owari than Ikeda although the per-
centage of Owari trees infected by canker was larger than that of Ikeda. Thus, from
the results of this experiment conducted with a fair number of plants over a period of
three years, absolutely no differences in the susceptibility of these two strains was
apparent. With only a few exceptions, canker was limited to the young growing
leaves and an occasional twig. On the other hand, the grapefruit plants were
very badly infected at all times during the season, canker being found on the
leaves, thorns, and round wood.
Citrus mitis Blanco proved to be more resistant than the Satsuma under field
conditions. Canker at all times was limited to a few young leaves and an occa-
sional twig. In the greenhouse experiments, the plants were more susceptible as
twig infection was common and occasionally the round wood was attacked.
Likewise, the Kansu orange proved to be decidedly resistant. Very few canker
spots on the leaves and no twig infection were noted. Of the other Citrus fruits
tested, all proved to be susceptible.
In the continued search among the Citrus fruits for promising canker resistant
types, the search will have to be confined to a few groups which show some promise
of being resistant to canker.
RELATIVE SUSCEPTIBILITY OF THE CITRUS HYBRIDS
Both faustrime and faustrimon are more susceptible than Microcitrus austra-
lasica (F. Muell.) Swingle. Faustrimedin is not as susceptible in that infection is
limited to a few spots on the leaves and an occasional twig.
All of -the Poncirus trifoliata crosses, including citranges, citrumelo, citradia,
citrandarin, citrunshu, cicitrange, and citraldin, are susceptible, and in no in-
stance can any one number be selected as showing enough resistance to citrus
canker to warrant its use as a canker resistant stock or orchard tree. While none
of these hybrids are resistant to canker, several of them stand out above the com-
mon level and may be of some use for further breeding and crossing purposes.
Throughout this investigation the Willets citrange has consistently shown less
infection than any of the other citranges. The fact that it is one of the parents
of the citrangequat, the most resistant hybrid so far found, substantiates to some
extent these results.
On the whole, it can be stated that when Poncirus trifoliata is crossed with any
of the more resistant Citrus species the resistance of the progeny-is lessened.
Of the four citrange crosses, citrangequat, citranguma, citrangarin, and cit-
rangedin, it happens that the second parent in each case is resistant to canker. Un-
fortunately, no hybrids were tested with a susceptible parent, so that we do not
know what is the direct influence of the citrange parent on canker susceptibility.
The citrangequat has consistently proved very resistant, in fact, as much so as
its second parent. It appears to be the most promising canker resistant hybrid
so far found. One disadvantage in the use of citrangequat as a stock has been the
small number of seeds produced. However, Swingle and Robinson 6 have recently
developed a method of propagation by the use of root cuttings, so that stock of
this hybrid can now be rapidly developed. If it is found that it will make as de-
sirable a stock as Poncirus trifoliata, it can replace the trifoliate orange, which at
the present time is a menace to the final eradication of citrus canker in the Gulf
Coast States. The other three citrange crosses, while they do not show as much
6 SINGLE, W. T., and ROBINSON, T. R. TWO IMPORTANT NEW TYPES OF CITROUS HYBRIDS FOR THE
HOME GARDEN-CITRANGEQUATS. AND LIMEQUATS. Jour. Agr. Research, 23: 229-238, illus. 1923.






Apr. 19,1924 Canker Susceptibility of Citrus Species and Hybrids 231

resistance as the citrangequat, are sufficiently resistant to warrant further trials
both as a stock and as orchard trees.
Limelo, orangelo, satsumelo, clemelo, siamelo, and tangelo, hybrids with grape-
fruit as one parent, vary in their susceptibility to canker. In no instance are
any of these hybrids as resistant as Satsuma to citrus canker, although a few
numbers are only slightly more susceptible. Because of the fact that one of
these hybrids, 'the tangelo, is being grown commercially and has merits which
are demanding attention from the orchardists and the public, the reaction of
these hybrids to canker is of importance. Until further information is at hand
it is safe to state that the tangelo and satsumelo, with some numbers of siamelo,
show enough canker resistance to place them beside the mandarin oranges in
their resistance to canker.
Likewise, the limequat and orangequat can be regarded as canker resistant
as Satsuma. The orangequat has been observed very closely in the field because
of its apparent similarity to the Satsuma, both in the type of growth and in its
reaction to citrus canker and scab. Its relation to the Satsuma, if there is any,
will not be known until fruit of the orangequat is produced and compared with
Satsuma. Oranguma and siamar are slightly less resistant than the above
hybrids.
Judging from the results obtained with the various hybrids of Citrus mitis, it
appears while somewhat resistant itself, it does not carry this resistance in the
hybrid. Thus, in the order of their susceptibility, we have sopomaldin, citraldin,
calarin, and calashu, which are equally as susceptible as the other parent, grape-
fruit, trifoliate orange, tangerine, and Satsuma, respectively.
In the search for promising canker-resistant plants, the results of over four
years' investigations seems to point to the fact that our best plants will come
from the hybrids. Already one or two of the hybrids showing almost as much
resistance as Satsuma have been set out in a small way. No doubt, as the
result of further tests by the Office of Crop Physiology and Breeding Investi-
gations, Bureau of Plant Industry, United States Department of Agriculture,
other canker-resistant hybrids will be found.
DISCUSSION
In Tables I, II, and III we have listed each number tested, giving the type
and number of plants used, its index of susceptibility, and the part or parts of the
plant attacked. The index of susceptibility is the maximum that the plant has
,shown while it was under investigation. The same is true of the parts of plants
attacked. Thus, the list as it stands records the maximum susceptibility shown
by the plants of each individual number.
It must also be remembered that for the most part these plants consisted
of small seedlings of budded plants. In only a few cases were the plants large
enough to bloom and set fruit. Further, they were fertilized to stimulate new
growth, for it was only on the new growth that canker developed in the majority
of cases. Also during the greater part of the work many of the more susceptible
plants were badly infected with canker, so that an epidemic condition existed
both in the greenhouse and field, and consequently natural infections could be
counted on at all times. Overwintering of canker in the field occurred each
season, so that during the last three seasons very few of the plants were inoculated.
In all of our publications on citrus canker one point has been continually
stressed, namely, that the plants must be in good growing condition for canker
to infect. In other words, the plant must be making a good, vigorous growth
to produce maximum infection. Therefore every means was used to keep the
plants in a good, vigorous growing condition during the investigation.
Under grove conditions with older trees no doubt many of the numbers tested
would show greater resistance to canker. However, the fact that under the
conditions existing maximum susceptibility was obtained renders the results more
valuable in that it gives us a truer index of susceptibility.







Journal of Agricultural Research


Vol. XXVIII, No. &


TABLE I.-Relative susceptibility of-the wild relatives of Citrus to canker


Num-
Genus and species B. Type of Location ber of Results
No. a plant plants


Rutaceous plants not closely
related to the genus Citrus
Melia azadarach.............
Xanthoxylum bungei----
Xanthoxylum sp............
Casimiroa edulis------.............

Toddalia asiatica---............
Glycosmis pentaphylla......-

Claucena lansium...........

Chalcas exotica-..............

Tribe Cttreae, subtribe Aeglinae
Aegle marmelos-..............

Aeglopsis chevalieri..........


Chaetospermum glutinosum.




Balsamocitrus dawei-......---

Subtribe Feroninae
Feronia limonia --............


Feroniella lucida ......-.----.
Subtribe Lavanginae
Hesperethusa crenulata-......


Triphasia trifolia ............


Paramignya monophylla....
Severinia buxifolia........--- -

. Subtribe Citrimae
Citropsis schweinfurthii.....


Atalantia citrioides -.......

Atalantia ceylonica-.........


Alabama
11180
11269
7923

11145
2905

7936

7975A
7980

7759
7983
7633

7772
7138
7799

----------
7814

2920
----------
7725

2763

11287
7882


2758
2759

2689A

7780
7874
2760
----------
11322

7999
11260

7534

11225


Poncirus :trifoliata....-------- Alabama

Eremocitrus glauca -- . ""--------


Fortunella margarita..---


Fortunella japonica ..........

Fortunella crassifolia......--


Fortunella hindsii...........


Microcitrus australasica .....



Microcitrus australasica san-
guinea.
Microcitrus garrowayi .......

Microcitrus australis.........


i7597
11302
11327
._11301

- 7946ib
11047
11047A
11046A

11319
7600

7600B

7775B1

11008

7307

7427

7775E


Seedling...
-..do.......
-..do-.......
.-_do-.......
-do---
.-.do-.-...
-.-do-.......
.--do.......
-do---
..-do---.......
---do-----
...do.......

-__ do---.......
.-do.......
---do -----.-
---do -------
Cutting_--
Seedling...
-.do-.......
.--do-.......
.-_do.......
-- do ---l-
Budded-b.
-- do.......
Buddede .

Seedling...
-- do-.......
-._do-.......
-.-do-.......
-. do-.......

-do---
---do ------.
-.-do.......
-...do.......-
-__do.......
---do ---
---do -------
Cutting...
-.-do.....
Seedling...

--do-.......
-- do-.......
!-do ---
Cutting. --
--do.....--
Seedling...

- do-----
_--do.......
-- do-.......
...do-.......
-..do.......-
_-_do-.......
--do-----
--do---
-do---
-do---
-..do-.......
--do-----
---do -------
--do .----
do.----
Cutting.. -
Seedling...
--do.----
- --d o --- ----
---do -------


Field.......
Greenhouse
--do--
.....do......
Field-......
Greenhouse
--..do......
Field-.......
Greenhouse
Field-.......
Greenhouse
Field ......-

--- do-......
Greenhouse
--- do.----
Field-.......
Greenhouse
Field-.......
Greenhouse
Field--....
Greenhouse
Field.----
Greenhouse
Field-.......
.....do-......

Greenhouse
Field --.....
----- do ------
Greenhouse
Field.......

.....do-......
Greenhouse
Field ---
Greenhouse
Field......
Greenhouse
--do---
- do.
Field. ..
..-- do .....-

--- do--.--
Greenhouse
Field ---
Greenhouse
Field-.......
Greenhouse

----- do --.---
Field-----
Greenhouse
Field ---.-
Greenhouse
Field.----
--- do----
Greenhouse
Field.----
--- do----
Greenhouse
Field .--
Greenhouse
Field.----
----- do ------
Greenhouse
Field .--
Greenhouse
Field. -
Greenhouse


Cutting-- -.... do-......
- do ----I Field.----
-- do.....--- Greenhouse
-- .do-...... Field ......
Seedling...I Greenhouse
-do ...--.-- Field ----.....
Cutting I....... do ---.--


Negative.
Do.
Do.
Leaves only at wounds.
Do.
Negative.
Do.
Do.
Leaves only at wounds.
Negative.
Leaves ofily at wounds.
Negative.

Do.
Leaves only at wounds.
Negative.
Do.
Do.
Susceptible minus.
Do.
Negative.
Susceptible minus.
Negative.
Do.
Do.
Do.

Leaves only, mostly at wounds.
Negative.
Do.
Leaves only, mostly at wounds
Do.

Susceptible minus.
Do.
Do.
Negative.
Do.
Do.
Leaves easily infected.
Negative.
Do.
Do.

Negative.
Leaves only at wounds.
Negative.
Leaves easily infected.
Do.
Leaves and stems easily in-
fected.
Extremely susceptible.
Do.
Susceptible minus.
Do.
Leaves only, resistant.
Do.
Negative.
Leaves only, resistant.
Do.
Negative.
Leaves only, resistant.
Negative.
Susceptible minus.
Do.
Do.
Do.
Do.
Do.
Do.
Do.

Do.
Do.
Do.
Do.
Do.
Do.
Do.


a Crop Physiology and Breeding Investigations. b On Aeglopsis chevalieri. c On Aegle marmelos.







TABLE II.-Relative susceptibility of citrus fruits to canker


Genus and species


C. hystrix, pointed-leaf form ................-----------------

C. hystrix, round-leaf form--...............----------- : -----------

C. medical, Citron of Commerce....----------------------
"Sidro ----------- ------ ---------------
"Odorata"...........------------...-- -----------
"Nana" ................................---------------------------------------
"Etrog"-......-- ----------------------------
Citrus sp. small lemon -----------------------------
Sweet......................---------------------------------------...
"Davao"-------......-------------------------------
"Limon real" No. 18----------------------
Ichang--..............-------------------------------

C. limonia. large lemon-------------------------.-------
C. aurantifolia, sour lime ----..---------.------------------
C. grandis, grapefruit-------------.---------------------

Sullivan ------------------------------
Shaddock Florida------------... -------...--
Pummelo "pomelo" --.....-----------------------
Hirado Buntan -------------------.

Indian --------------------------


Siamese --..--------------------


Chinese Orangedale ------------------.
French Martin...........-----------
Mark's.....----------------


Nu
ber
plain


C. P.B. Type of Location
No.a plants


7727 Seedling-..-- Field ......-
7872 .....-do...... Greenhouse.
. -- --- do ---- Field.------
2881 .. do ------ Greenhouse-
7831 .....-do-----.......----do......
..------ .....do...... Field .....--
7768 Cutting-..... Greenhouse.
7836 Seedling-......... do ..-..
7816 -----do----......--..do......
11294 .-....do.------..... ....---do ..
11281 --....do------..........do ...---
11178 -....do.-----.........do......--
7833 .....do.-----..........do ....---
1158 .....do .........------do---......
7837 .....do -----...........do......
7819 - do--- -----do----
11204-A .....do-------...... do-----...
...... . do-.... Field .--
11291 .....do...... Greenhouse-
7832 --- do--------- do----
7338 -.. do -------do----
7903 ..do---- Field----.-
11170 .....-do---..... Greenhouse.
Alabama ....do ------ ---..do-......
11001 .....-do-.... Field ....
11054 .....-do-----.........---do......
11255 -.....do..........--- do.....
7834 -----do---- Greenhouse-
7993 --- do----- -- do---.
.. . ... ..-do..... Field ....--
2968A ....do--- ... Greenhouse.
.... do..... Field-.......
11163 .do----- ----do----
1116 .....do .....--- .....---do ---....
6111 Budded... Greenhouse-
-o-'o-- Field----
11201 Seedling- - Greenhouse.
..... do ---- Field-......
11212U ....-do --.....-- .....I ---do......
11213S .....do......-.....do ......
11061 ..- do----I Greenhouse.
- -----do------ Field---
112 .....do ------......--do....--
112170 -.....do ------.......---..do......


a Crop Physiology and Breeding Investigations. b On Citrepsis schweissfssrllzit.


m-
of Results Remarks
its

2 Susceptible minus --- Leaves and occasional twig.
2 ....do..............--------.. Do.
12 -- do--------------- Do.
1 Susceptible plus.----- Leaves, twigs, and round wood.
2 -....do--------------- Do.
2 .....do--................ --Do.
2 Susceptible...----------- Do.
1 --.....do--------------- Do.
2 -.....do ......-------------- Do.
2 -.....do.............---------.. Do.
2 -.....do------------ Do.
2 -- do ----------------Do.
2 -.....do ............-------.. Do.
2 -.....do----------------....... Do.
2 -.....do ----------------. Do.
2 .....do---........----......------ Do.
3 --do --------------. Leaves and occasional twig.
4 .....do...............----------. Leaves, twigs, and occasionally round wood.
4 -..... do----......----------..... Leaves and occasional twig.




3 -.....do............-------.. Do.
3 -.- do--------------- Do.
3 .....do ------------ Leaves, twigs, and round wood.
2 ---do---------------- Do.
3 Susceptible minus..---- Leaves and occasional twig.
3 .....do --------- Do.
2 Susceptible plus-.....----- Leaves, twigs, and round wood.
2 -.....do --------------- Do.
3 -....do ---------------- Do.
2 ---do---..------------- Do.
I Susceptible minus-..... Leaves only.
1 Susceptible.........-----------. Do.
2 --... do ----------------Do.
3 Susceptible minus ..---- Leaves and occasional twig.
3 Susceptible plus---..... Leaves, twigs, and round wood
I ---.do---------------- Do.
2 ....-do ----------.-----...Do.
3 Susceptible-..-- - Leaves, twigs, and occasionally round wood.
3 -.....do..........--------......Do.
3 -.....do -------........--------... Do.


a Crop Physiology and Breeding Investigations.


b On Citropsis schweinfurthii.


I









TABLE II.-Relative susceptibility of citrus fruits to canker-Continued


Num-
Genus and species C. P. B. Type of Location ber of Results Remarks
No. plants plants


C. sinensis, orange.......-----------------................................
Grenadine----------..............................
Parsons Brown-----.-........---....
Navel. --------------
Temple.................... ......
Temple---------- -------
Japanese No. 1 ----------
Japanese No. 2 ----------
Sekkan...............-------------
Pankan.....--.........................----------
Tankan -- ------------.........................
South Carolina--------..---------------
Kirkland-...............................
C. nobills, King of Siam...............-------------...................

Naranjita .................--------------------...................
C. nobilis, unshiu, Satsuma..----------------------........----
C. nobilis, deliciosa, Tangerine.....................-------------
Cleopatra----------- .............-----------

C. mitis, Calamondin .......................................




Citrus sp. Kansu-----......................................------------





Citrus sp. Natsu-mlkan...........-----.......................-----------------..



Citrus sp. Talamisan No. 11-................................
Colo-colo......-----------................................
Tegi-tegi.......--- ................................
Naranja........------------------...............................----------------

Narute ------ .... ..............--------------------------
C. excelsa .................................................----------------------


66A
7773
11324
45344
11164
11198
11199
11023
7560A
7562
11028
11313
2105
11384
7830
Alabama
11195
11338

7065
11265

i11312
44305
7908

11242
11298


11184i


11337
7827
7820
7818
7829

11196
11280


Seedling ....--
.....do......
.....do......
Budded ....
Seedling-...--
.....do ......
.....do......
.....do-......
.....do-......
.....do......



..do-....
- do.-
Budded_...
Seedling--..-
.....do-......
.....-- do-......
.....do --...
.....do-......
.....-- do-......
.....do-......
.....do-......
.....do......
--do---
.....do-......
---do.---.-
Budded',-
Budded'--.
Seedling-. -
--- do---. .
--do--
--- do.----
--do-.
--- do.----
.-- do---...
--- do--....

.-do-..
.-.do-..
-.do ....


Greenhouse.
--- do......
.....do---...
Field -----
.....do-......
.....do-......
--do ---
.....do....--
.---do---
.-do- .
.....do-......
--....do-......
Greenhouse-
Field-........
Greenhouse.
.....do......
--- do.---
--.....do-......
Field ----
Greenho
--- do.----
Field........
-- do......---
Greenhouse.
Field.-----
.....do......
Greenhouse-
Field .......
--..... do---......
..-.do----
Greenhouse.-
Field .....----
--do---
-.....do- ....
Greenhouse.
--do.-
--- do.---.
-.do...
Field.-----
..r--do--e.
Greenhouse.


Susceptible ..........-
..... do -----...........
.....do-...............-
----- do ----------------
.....do...............------
.....do ..-........---
....do-................
-..... do -------...............
--do-------
--do-------
Susceptible plus ----
Susceptible .....---------
Susceptible minus- --
.--do-------
.....do..-------.............
.....do-------
.....do..............--
---do -------
.....do ..-------..........
--do-------
.....do-................
.....do..............-----
-- do ---------...........
.....do -------............
----- do -------........
.....do-................
--- do ----------
--- do ----------
--. do -----------
-- - do -----------
Susceptible ----..-----
.....do-...............-
.....do-...------------.
--do-------
Susceptible plus .-----
--- do-------.-----
Susceptible minus - -.
Susceptibl ---------
--- do -----------
--- do -----------
--- do -----------


Leaves and occasional twig.
Do.
Do.
Do.
Do.
Leaves, twigs, and occasionally round wood.
Do.
Leaves and occasional twig.
Do.
Do.
Leaves, twigs, and round wood.
Leaves and occasional twig.
Do.
Do.
Do.
Leaves only.
Do.
Do.
Leaves and occasional twig.
Do.
Do.
Leaves only.
Do
Leaves and occasional twig.
Leaves only.
Do.
Leaves and occasional twig.
Leaves only.
Do.
Do.
Leaves, twigs, and occasionally round wood.
Do.
Do.
Do.
Leaves, twigs, and round wood.
Do.
Leaves and occasional twig.
Do.
Leaves, twigs, and occasionally round wood.
Do.
DO.


On Pencirua trifeliste. On Citrus grand:s. On Scetrfnfa twrifelie.


* On Ponciru trifoliata.


d On Citrus grandis.


* On Severinia buxifolia.







TABLE III.-Relative susceptibility of citrus hybrids to canker


Hybrid


Faustrime (M. australasicaXC. aurantifolia)-.............


Faustrimon (M. australasicaXC. limonia)-...............-


Faustrimedin (M. australasicaXC. mitis).................-------

Citrange Colman (P. trifollataXC. sinensis)..............
Cunningham ..........-.......................-

Morton....................---..................

Rusk..........................................






Willits........................................


Savage....................--..----.................--



Sanford........------------...............................--

Rustic----------...........................-----------.........---.-------
Etonia..........---...............................-----------
Citrange......................................----------------------------..--........------




Citrumelo (P. trifoliataXO. grandis)......................




Citradia (P. trifoliataXO. aurantium).................-----
* Crop Physiology and Breeding Investigations.
0


C. P. B.a
No.


49819
49823
49835
49841
49843
49844
47431

772AC
7896
1418AA
7965
761AC
771A
716
7895
7895Y
7956
-11030
44980
777AB
7897
7960
779AA
7898
7961

""1423AB'
7963
7934A
749AB
1416
1425AB
443434
43480
e 48931
1425AA
4475A
4493
4554
4564
50860


Type of
plant

Cutting-.....
.....do......-
.....do-......
.....do-......
--do--
.....do......
-do
.....do......
Seedling....--
.....do......
.....do-......
.....do-......

.....do-......
..-..do-......
.....do-......
.....do-......
.....do......-
.....do-......
.....do-......
.....do --...
.....do......
.....do-......
--do --
--do.---
---do--
.....do-......
.....do......--
.....do-......
--do---
--do--
--do--
.....do......-
-- do...
--- do.-...
..- do.---
--- do.----
--- do.----
..-do..
--- do.--..
--- do----
--- do.--..
--- do.---

..-do-..


Location


Greenhouse.
--.....do-......
--do--
.....do-......
---do---
.....do-......
.....do-......
Field--......
.....do-......
Greenhouse.-
Field....---
Greenhouse.
.....do-......
.....do-...
Field-.......
-- do ..---
Greenhouse.
--do.--
Field......---
Greenhouse.
.....do-......
Field-........
.....do-......
Greenhouse.
.....do-......
- --- F ield .. -
.....do .....d
--.do---
Greenhouse.
Field.-----
.-. do .---
Greenhouse.
--. do----
Field-----
Greenhouse.-
Field-----
Greenhouse-
--. do.---
--. do----
Field-----
Greenhouse-
--. do----
--. do----
--. do ----
--. do.--.-


Nl
ber
pla1


Remarks


In-
of Results
nts

1 Susceptible-...........
1 -.....do-................
1 -.....do-................
1 -.....do-................
1 .....-do-...............
1 -.....do...............------
2 --- do ----------
2 --- do ----------
2 Susceptible plus-.......
2 -.....do-................
2 ..- . do..............-----
2 -.....do................-
2 -.....do................-
2 --- do--------
2 ----- do ----------------
10 -- do-------
2 ----- do ----------------
2 -.....do-................
S.....--do...------..........
3 --- do.----------


3 Susceptible ..------


3 Susceptible plus..--
4 --....do-................
2 -.....do..--- ---............
S.....--do................------
3 --.....do-................
2 -.....do-................
2 --.....do................-
2 --.....do-................
2 --....do-................
1 --.....do..---............---
2 -.....do ..------............
2 ..-...do................
2 -.....do-................
2 ---- do ---------
1 --- do-------............
2 --- do............-------
4 --- do -------............
2 --do------
2 Susceptible-----........


Leaves, twigs, and round wood.
Do.
Do.
Do.
Do.
Do.
Leaves and occasional twig.
Do.
Leaves, twigs, and round wood.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Leaves and occasional twig.
Do.
Do.
Leaves, twigs, and round wood.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
SDo.
Leaves, twigs, and occasionally round wood.










TABLE III.-Relative susceptibility of citrus hybrids to canker-Continued

0. P. B. Type of Location Results *Remrks
Hybrid No. plant ber of Results
No. plants


Citrandarin (P. trifoliataX C. nobilis) -----..............------





Citrandarin (P. trifoliataxC. nobilis unshiu)..----------







Citrandarin (P. trifoliataX C. nobilis deliciosa) ------.......









Citrunshu (P. trifoliataXO. nobilis unshiu)----..---







Cicitrange (P. trifoliataXColman citrange).....------

Citrangequat (Willits citrangeXF. margarita)--.........---





Citrangequat (Willits citrange x F. margarita) --.----.......---


40175A Seedling--.. -
40210 .....--do-......
403030 .....-do...-....
40315 .....-do..-...
40368B .....-do-.....-
48529 Budded b...-
49720 Seedling--...
49721 .....do.....-
49724 .....-do......-
49726 --.....do-....--
49732 .....do .....-
49737 ..-...do......
49746 --.....do......-
49748 .....do.....-
49624 .....-do......-
49625 .....--do......-
49644 .....-do-......
49663 ....-- do-..---
49664 .....-do......-
49686 .....-do.....-
49688 .....do-......
49695 .....-do......-
49699 .....-do-......
49712 .....-do ..----
49607 .....-do..-.....
49608 -.....do-....--.
49611 --... do-....-..
49615 .....-do ..-...
49620 .....do-.......
49623 .....-do.......-
...........-- do.......
51102 Budded b_...
48290 Seedling-.....
48316 .--..do--..-
48003 Budded c
48005 Budded da-
48007 Budded e.
48010 Seedling ....
48010 Budded .. - -
48010D2 Seedling-.....
48010D5 Seedling.....-
48010E1 -.....do.....--
48010E .....-do-.......
48010E Budded f---
48010F Seedling--.....
48011 Budded d --


Field.....-- -
Greenhouse.
.....do ..----
.....do-....
.....do-...-.
.....do ....---
Field ......---
.....do ---....
.....do......-
.....do ...---
.....do....---
.....do...---
.....do-.....-
....--do-.....-
.....do......-

---- do....._
.....do-....-.
.....do ..---.
.....do......
.....do......-
.....do-......
.....do-......
.....do ---
.... do....--
.....do......
.....do.----
.....do......-
... do .
-..--do:::::


Greenhouse.
-- do..--
Field ----
-..-- do .----
----do .--- -
Greenhouse-
Field...---
Greenhouse-
Field ------
Field.....
..--- do-..--
--.....do--....
.. do .
.....do.....--
.....do.......


I


Susceptible --------.......... Leaves, twigs, and occasionally round wood.
---- do -----------. --- Do.
..... do ---------.............------- Do.
..... do ---............------------. Do.
..... do -----------.----- Do.
....--do ----------------........ Do.
....--do ---------.............------- Do.
....--do ----------------............. Do.
.....do --- ----------- Do.
.....do ----------------- Do.
--...do --------.............-------- Do.
do --...-------------.. Do.
do..------..--.. --- Do.
.....do----------.........------. Do.
.....do -------.......--------- Do.
.....do --------------- Do.
.....do --------............ ---- Do.
.....do ---------...........------- Do.
-....- do ---------------- Do.
....-- do --..........----------..--. Do.
-.....do --..........----------..--. Do.
.....do -----.-----------............ Do.
.....do -------.......--------- Do.
--.....do ---------------- Do.
....: do ........-------------...... Leaves, twigs, and round wood.
.....do ----.........-----------.... Do.
--..do --........... Do.
.....do -----.....---.--------...... Do.
---. do ----------.............------- Do.
.....do ----------.............------- Do.
----do ----------------- Do.
---do ---- ---............. Do.
Susceptible plus---...... Do.
---..do ----------------- Do.
No infection...........
Very resistant------ Leaves only.
No infection .------
Veryresistant---------...... Do.
No infection.-----------...... Do.
Very resistant-------...... Do.
----do ...........---------------- Do.
--.....do . ---------------- Do.
No infection...........-
--.....do-----------
Leaves only------.......... Very resistant.
No infection-.......----










Citranguma (Morton citrangeXO. nobilis unshiu)-........






Citrangarin (Sanford citrangeXC. nobilis deliciosa) ---.....

Citragedin (CitrangeXC. mitis)--------..............--.....














Limequat (C. aurantifoliaXF. margarita) ...--.........---...--



Limelo (C. aurantifoliaXO. grandis).....................--------

Bigaraldin (C. aurantiumXC. mitis)......-------.......--------

Orangelo (C. sinensisXC. grandis)-........------........--------.....---

Oranguma (0. sinensisXC. nobilis unshiu)...---....---------....


b On Poncirus trifoliata.
f On Severinia buxifolia.


48379
48888
48897
48054
48055
48055A
48217
48218
49773

49776

48045
50207"
50479
50485

---50486
50493
50495
50498
50500



48787A
48787B
48792E
----48798
40502
40526A
40567B
50352
50355
1668
49107
49132
52117
52118
52129
52131
52142
57121


d On Citrus grandis.
- On Citrus aurantifolia.


..... do----...........do.......
..... do----...........do.......
..... do ----..........----do.......
Budded g .-- . do ---
Seedldng --- Greenhouse-
.... do----........---do-.......
Budded b.. Field-........
Budded--- --.....do-.......
Seedling .....-.....do-.......
Budded-- ........do-.......
Budded- ...-.....do-......
Seedling -..........do-.......
Budded-- --........do-....--
Seedling-..... Greenhouse.
Budded --- Field --
..... do-----..........do.......
..... do-------...........do.......
----- do -------. ..... do -------
Seedling -..........do.......
Budded b - --do---
..... do-----.........do.......
..... do--.....--.. -----.....do-.......
Budded --...--.....do-.......
Budded d-- -- do--
Budded--- -- do-

-- do------ ---do---
Budded b- --do--
Budded -... .....do ......
Budded d........- do....
Seedling--- Greenhouse.-
- do------.........---do-.......
..... do ......-----.....-- -do ......
-- do--....... Field---......
Budded ...... --do-......
Seedling-..... Greenhouse.
..... do--...... --....---do.....
--- do------- ---do----
Budded b ... ield-.......
Buddedd-- ---do--
Seedling- . --do--
Budded d-- -- do--
..... do-----...........do.......
..... do-------...........do ......
Budded i -- ----do-....-..
Budded --... .....do-.......
Buddedd-- --........do--.....
Budded --... --....do-.......
Budded -... .....do.......-
I On Citropsis schweinfurthii.
SOn Citrus limonia,


Very resistant .......- Leaves only.
.....do .._ - Do.
--..... do ------- Do.
Susceptible ---.- Leaves, twigs, and occasionally round wood.
Resistant --- --- Leaves and occasional twig.
Susceptible minus..... Leaves, twigs, and occasionally round wood.
Susceptible ------.....-----.... Do.
.... do ....-----------------....... Do.
.....do .-----....------------...... Do.
..... do...----------------....... Do.
.....do ---....... Do.
Susceptible minus-..... Leaves and occasional twig.
-----do ----.-----------. Do.
.....do .........--.--...... Leaves only.
-- do ---------.-------- Do.
do .-------------. Leaves and occasional twig.
.....do -----------------......... Do.
.....do ----------....... ------ Do.
.....do ..--..---.--.......---.. Leaves only.
-.. do----------------.. Do.
do ----- -------- Leaves and occasional twig.
.....do .--...----.---------........ Do.
.....do .......---------------- Do.
.....do .........-----------.... Leaves only.
-- do ---------------- Do.
-- do ------------- Leaves and occasional twig.
-- do --------- Leaves only.
-- do ---------- Leaves and occasional twig.
.....do ...-------....... Do.
.....do..... --......--. Do.
.....do ....-----------------....... Do.
....do -----------------....... Do.
.....do ........--......... Do.
.....do -----------------........ Do.
.....do ---------........-------- Do.
Susceptible plus....... Leaves, twigs, and round wood.
.....do ....----------------....... Do.
.....do .................------ Do.
Susceptible ----------....... Leaves, and occasional twig.

--do -------------Leaves, twigs, and occasionally round wood.
Susceptible plus------ Do.
....--do........--------------....... Do.
Susceptible --.....--------.. Leaves and twigs.
..... do ----------........------- Do.
..... do ---.....-------------..... Do.
..... do ........-----------. Do.
..... do ---..-------------..... Do.
..... do ---------.........------- Do.
h On clemelo. i On Rusk citrange.
On Savage citrange. A On Citrus nobilis deliciosa.









TABLE til.-Relative susceptibility of citrus hybrids to canker-C-ontinued



Hybrid . B. t Location ber of Results Remarks
HydNo. pnt plants


Orangequat (C. sinensisXF. margarita)-...................

Satsumelo (C. nobilis unshiuXC. grandis)-...-----...
















Clemelo (C. nobills deliciosaXO. grandis)-.................










Siamelo (C. nobilisXC. grandis)................----------.........


49956
50312
48812
50304

'"62001Bi"
5200312
52009A2
52009G5
52009Q1
52009V4
52010F1
52011M1
52011R1
52011Y4
52022P1
52032H1
52304
49006
49013

490258
49028
49032
49038
49043
49049
47355B
50520
50535
50551

51531
51565
51584
51586
51588
51598
51947
51969
52007-06
52007-P3
52007-P11


Budded I---....
Budded b...
Budded *...
Budded ..
Budded g...
.....do-.......
.....do-.......
Budded d_..
.....do-.......
Budded -...
.....do-.......
-- do---....
.....do-.......
Budded d ---
---do --
Budded o---

Budded b-d.
Seedling ---
Budded b --.
Budded d ---
Budded b __--


.....Bdo...--.
Budded 4. --
Budded b __
--do--
--do--
Budded d- - -
Budded b---
Seedling---....
Budded ...
.....do-......
.....do......
.....do-......
.....do-......
.....do-......
.....do-.....
.....do......
Seedling--.1
.....do......

Budded d --
.....do......
.....do-......
--- do.---


Field .......-
.....do-.......
.....do-.......
Greenhouse
Field-........
--...do-.......
.....do-.......
Greenhouse-
.....do-.......
Field-........
.....do-.......
.....do-.......
.....do-.......
.....do-.......
.....do-......
.....do-......
.....do-......
.....do-......

.....do-......
.....do-......
.....do-......
-....do......
-.- do.---
--- do.---
--- do----
--- do.---
-.- do .---
.Greenhouse -
Field-.......
.....do-......
.....do-......
.....do-......
.....do-......
.....do-......
.....do-......
.....do-......
Greenhouse. -
.....do-......
Field-----
.....do-......
---do..---
--- do.---
--- do.---


Susceptible...........
.....do-.................
..-- do-.................
.....do-.................
.....do-.................
.....do.................-
.....do-.................
.....do................-
.....do-.................
.....do......-------..........
.....do-.................
.....do...-------............
.....do-.................
.....do-.................

.....do-................
.....do-------

Susceptible plus ......-----
-....do................-
----- do --------......
---. do...-------
.....do-................
.....do-................
--....do................
.....do-................
--....do-................
.....do-................
Susceptible -----------
--- do -----------
Susceptible plus -----
Susceptible -------
.....do-................
.....do-................
--- do -----------
--- do ----------
--- do -----------
--- do --------
--- do --------
--- do-------
--- do ----------
--- do------
--- do ----------
--- do--.--------


Leaves only.
Leaves and occasional twig.
Do.
Leaves only.
Leaves and occasional twig.
Do.
Do.
Leaves only.
Leaves, twigs, and round wood.
Leaves and occasional twig.
Do.
Do.
Do.
Leaves only.
Leaves, twigs, and round wood.
Leaves and occasional twig.
Do.
Do.
Leaves, twigs, and round wood.
Do.
Leaves and twigs.
Do.
o Do.
Do.
Do.
Leaves, twigs, and round wood.
Leaves and twigs.
Leaves, twigs, and round wood.
Leaves and twigs.
Leaves, twigs, and round wood.
Do.
Leaves and twigs.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.
Do.








52013-89
52021-A5
Siamor (C. nobillsXC. sinensis)-....----------..........---.---........... 52020-Cl1
52029-011
52029E
Calasbu (C. mitisXC. nobilis unshiu) --.....................- 50309

Citraldin (P. trifoliataXC. mitis) ...................--------- 50130
Sopomaldin (C. grandisXC. mitis)--......-----.................. 50378
50393

Calarin (C. mitisXC. nobilis deliclosa) .................... 50314
Tangelo, Thornton (C. nobilis deliciosaXCO. grandis) ...... L715
714B
11034
Sampson----................---..............----------------------- L789
7764
11037
Vero..........----......--...................----------.......... 11340
Tangelo.................------------........-------------------------------.... L16
L461
1191
1230
1257A
1262B
1348A
7161
76750
40971A
52018C2
52018F2
49425
49818114
49879
50312
52016012
52016D6
52016E4
52018A4
52018N1
52018S3
52018U2
52018X17
False hybrids.................--------------......................----------------....... 11 nos.....
10 nos .....


6 On Poncirus trifoliata.
d On Citrus grandis.


..... do---....--. .....do......
..... do..----.....do-......
..... do--.....---......do......
..... do-----........do......
..... do...... Greenhouse -
Budded _..- Field.......
Budded -........ do-......
Budded d--... ..... do-......
..... do----.........do......
..... do---....-----.....do......
--- do------ --- do-----
Budded --- --........do......-
Budded b-- --- do.-----
Seedling---.... Greenhouse-
..... do...... Field.......
..... do...... Greenhouse -
..... do---....-----.....do......
..... do...... Field.......
..... do---....-----.....do......
.....do--..---........-do......
.....do...... Greenhouse -
---..... do .-..... .....- do-......-
.....do----.... -- .....do......
.....do-.......-- -....do-......
.....do.....---....--..do-......
..... do.----.........do......
..... do---....-----.....do......
..... do.---....-----.....do......
..... do ...... ..... do ......
..... do ...... ..... do ......
Budded d-........do-.....-
..... do------ --.....do......-
--.....do---...... Field.......
--.....do---...........do-......
..... do-----..... ..---do......
Budded- --........do......
Budded--- --........do-----......
..........--- --........do-......
--..... do ----...... --..... do-......
--.....do......--- -.....do-......
Budded - ........do-......
..... do-.....-- --.....do......
.....do-...........do......
.-.do--.------do- -
Seedling.--- Greenhouse.
.....do-..... Field.......


g On Citrus liUonia.
t On Savage citrange.


Susceptible plus...... Leaves, twigs, and round wood.
Susceptible-----.......... Leaves and twigs.
.....do ------------ Leaves and occasional twig.
.....do...............------- Do.
.....do......-------.......... Do.
Susceptible minus..... Leaves only.
-....do...............------- Do.
.....do .....----.--.......... Do.
Susceptible........... Leaves and twigs.
Susceptible plus...... Leaves, twigs, and round wood.
Susceptible . .-----
Susceptible plus--. Do.
Susceptible.........---.. Leaves and twigs.
.... do-...............-------. Leaves, twigs, and occasionally round wood.
..... do...............------- Do.
..... do...............------- Do.
.... do-------------- Do.
....do--...............---- Do
.....do...............------- Do.
..... do........--------........ Do.
..... do...........----------..... Do.
..... do........--------........ Do.
..... do...............------- Do.
..... do-------------- Do.
..... do........--------........ Do.
..... do--------............... Do.
..... do.............-------... Do.
..... do........--------........ Do.
..... do...............------- Do.
..... do--...---.--............ Do.
.....do................-------- Do.
.....do.......--------......... DO.
.... do-.........----....... Do.
.... do................------ Do.
..... do........--------........ Do.
..... do -.........----....... Do.
..... do.--.......---........ Do.
.... do................ Do.
..... do.............----- Do.
..... do................------ Do.
..... do---............... Do.
..... do----............... Do.
.....do---............... Do.
.....do---............... Do.
Susceptible plus...... Leaves, twigs, and round wood.
.....do................------ Do.


I On Rusk citrange.
I On Citrus medical.


m On Natsu-mikan.


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