Physiologic races of Puccinia graminis in the United States in 1939

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Title:
Physiologic races of Puccinia graminis in the United States in 1939
Physical Description:
14, 2 p. : ill. ; 27 cm.
Language:
English
Creator:
Stakman, E. C ( Elvin Charles ), 1885-1979
Loegering, W. Q ( William Quenn ), 1912-
United States -- Bureau of Entomology and Plant Quarantine
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U.S. Department of Agriculture, Bureau of Entomology and Plant Quarantine
Place of Publication:
\Washington, D.C
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Subjects / Keywords:
Wheat rusts   ( lcsh )
Puccinia graminis -- United States   ( lcsh )
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bibliography   ( marcgt )
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Bibliography:
Includes bibliographical references.
General Note:
Caption title.
General Note:
"E-522."
General Note:
"January 1941."
Statement of Responsibility:
by E.C. Stakman and W.Q. Loegering.

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University of Florida
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All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 030270988
oclc - 79974650
System ID:
AA00023013:00001

Full Text


E-522 January 1941











PHYSIOLOGIC RACES OF PUCCINIA GRAMINIS
IN THE UNITED STATES IN 19391


By E. C. Stakman and W. Q. Loegering,2
Division of Plant Disease Control



Introduction

For more than 20 years annual physiologic race surveys of Puccinia
graminis have been made in the United States to determine the prevalence,
geographic distribution, and population trends of the various known races of
Puccinia Kraminis and to find out whether new ones arise. The results are
valuable in epidemiology studies, in explaining varietal behavior, and in
breeding resistant varieties. It seems desirable, therefore, to make the re-
sults available each year in printed or multigraphed summaries. The results for
1939 are given in tables 1 to 9 of this report.


'Cooperative investigations between the United States Department of
Agriculture and the Minnesota Agricultural Experiment Station. Paper No. 1840
of the Scientific Journal Series of the Minnesota Agricultural Experiment
Station.
Assistance in the preparation of these materials was furnished by the
personnel of the Work Projects Administration, Official Project 65-1-71-140,
Subproject No. 458. Sponsored by the University of Minnesota, 1939 and 1940.

aUnfortunately, it would require too much space to give individual credit
to all those who have cooperated in this survey by sending collections of rusted
material. Most of the collections were made by the personnel of the barberry
eradication project of the Division of Plant Disease Control, Bureau of Ento-
mology and Plant Quarantine, especially the State leaders and men working under
their direction. As in the past, W. T. Butler, agent, collected a very large
number of samples throughout the Mississippi Valley. Several members of the
Division of Cereal Crops and Diseases, Bureau of Plant Industry, also made
collections, especially H. B. Humphrey, J. A. Clark, C. 0. Johnston, E. S.
McFadden, and I. M. Atkins. Donald G. Fletcher, executive secretary of the
Conference for the Prevention of Grain Rust, also furnished collections. Thanks
are due all these individuals for making it possible to conduct the survey on
an adequate scale.




-2-


Explanation of Terminology

The meaning of some of the terms may not be clear without explanation.
A collection of stem rust is an indefinite quantity of infected host material
collected within a limited locality. In the case of the uredial stage, a col-
lection may consist of only one or a few pustules on a single plant, when rust
is scarce, or it may consist of many pustules on several stems, leaves, and
heads collected in a single field. In the case of the aecial stage, a col-
lection consists of one to many infected leaves from a single barberry bush or
group of bushes growing near each other.

When rust from a collection is used to inoculate seedling plants of 12
differential wheat varieties, the resulting type of pustule, known as infection
type 1, 2, 3, etc., forms the basis for identifying the race or races in that
particular collection. These infection types have-been described in detail by
Stakman and Levine,$ who also outline the method of identifying races. It
should be remembered that under the normal range of conditions in which race
identifications are made, a given race will produce the same general pustule type
on a given differential host; but variations in conditions, especially light and
temperature, may result in corresponding variations in pustule types. It is
necessary to use the word "isolate" because two or more races often are isolated
from a single collection of rust, as illustrated in figure 1.

Figure 1 represents the results of inoculating the differential varieties
of wheat with the rust as it was obtained from the field. There are two in-
fection types on Marquis, types 4 and 2. Obviously, therefore, there are at
least two races present. On Reliance there are type-4 pustules only, but the
number is only about 33 percent of the total number of pustules on Marquis.
On Arnautka, Mindum, Spelmar, and Einkorn the number of type-I pustules corre-
sponds with the total number of pustules on Reliance. It seems likely, there-
fore, that the race causing the large pustules on Reliance is causing the small
ones on the three durums and Einkorn. It would seem that it might also be pro-
ducing the type-2 pustules on Marquis, but knowledge of races makes this seem
doubtful. The most likely combinations would be races 17, 19, and 56, but this
is not certain. Therefore inoculations were made as indicated in the diagram,
and the results prove that this surmise was correct. In this case, then, three
isolations were made: Isolate I proved to be pure race 19; isolate II was pure
race 56; and isolate III contained both race 19 and race 17, the only difference
being that 17 produces type-4 pustules on Marquis and 19 produces type-2.

It turns out, then, that three isolates were obtained from this col-
lection of rust. In a given collection the number of isolates or isolations
corresponds with the number of races identified. In the illustration chosen,
for example, several other methods could have been used for arriving at the same
result. A limited number of the differential varieties, known as a "half ser-
ies," could have been inoculated with rust from the type-i pustules on the


3Stakman, E. C., and M. N. Levine. The determination of biologic forms
of Puccinia graminis on Triticum spp. Minn. Agr. Expt. Sta. Tech. Bull. 8.
10 pp., illus. 1922. (Mimeographed keys and tables for identifying races are
available.)






- 3 -


three durums or Einkorn (after increasing the rust on a susceptible variety to
obtain enough inoculum), but race 56 would have been identified from these
isolations as it was when transfers were made from Reliance. Even though race
56 had been obtained in several series of isolations from one collection, it
still would count as one isolate.

A "half series" is shown in figure 1 and includes the varieties Marquis,
Reliance, Kota, Arnautka, Kubanka, and Einkorn. From long experience it has
been found that Arnautka, Mindum, and Spelmar react alike to practically all
the common races of stem rust, as do Kubanka and Acme.4 Therefore, after ob-
serving similar mixtures of type-4 and type-i pustules on Arnautka, Mindum,
and Spelmar, and complete susceptibility on Kubanka and Acme, it is sufficient
to inoculate one variety from each group. Arnautka and Kubanka are commonly
used for this purpose. In the case of Vernal and Khapli, which were completely
resistant in the illustrations used, it must be concluded that these two varie-
ties are resistant to all races in the mixture and need not be tested further.
If either of these varieties shows a mixture of two infection types, then that
particular variety must be included in the "half series." If there is doubt in
any case concerning an identification made on the basis of a "half series," the
isolate is tested on a complete series of differentials.

In the summaries, the percentage figure given for each race simply indi-
cates the relation between the number of times that that race was identified
and the number of times all races were identified. For example, race 19 was
isolated 40 times in the United States, and the total number of isolates was
1,158 (table 3); hence race 19 constituted 3.4 percent of all race isolates in
the United States. It is important to keep in mind, however, that the percent-
ages given in such summary tables as table 2 merely indicate the number of times
each race was identified in relation to the number of times all races were
identified. Consider race 56 in table 2 (uredial) and table 4. It was identi-
fied 590 times, and a total of 1,063 identifications were made of 14 races
in 735 collections; that is, there were 1,063 isolates from 735 collections.
Accordingly, race 56 constituted 55.5 percent of all isolates. However, it
should be remembered that the percentage figures in the summary tables might be
on the basis of number of field collections rather than number of isolates.
For example, race 56 was isolated from 590 collections of stem rust out of a
total of 735 collections, or from 80 percent of the collections.

Neither the percentage of total isolates nor the percentage of col-
lections in which each race was found necessarily shows the relative amount of
inoculum of that race in the stem rust collections identified in the survey.
If it were desired to arrive at this, the proportion of each race in each col-
lection would first have to be computed on the basis of number of pustules pro-
duced on one or more of the differential varieties by one race in comparison
with the number of pustules produced by the other race or races present.

For example, assume the presence of races 19 and 56 in a collection, as
shown in figure 2. In this case the ratio of race 56 to race 19 is 70:30, that
is, race 56 constitutes 70 percent of the rust, and race 19 constitutes 30
percent.

4Especially those concerned in the present report.





--4 -


Similarly, in figure 1 it can be seen that the amounts of races 17, 19,
and 56 were approximately in the ratio of 33:33:33. Following this procedure
with each identification, an attempt could be made to arrive at the relative
amount of inoculum of at least the more common races in the collections as a
whole. Thus, in 1939 race 56 constituted by far the largest proportion of the
rust in the collections in which this race was mixed with other races.

Collections from Barberry

The three varieties of Puccinia graminis that attack small grains were
well represented in the aecial collections (table 1). Forty-six percent of the
173 varietal isolates proved to be wheat stem rust (P. graminis tritici), 34
percent were rye stem rust (P. graminis secalis), and about 20 percent were the
oats stem rust (P. graminis avenae). These results show clearly that these
three varieties all develop on barberries and that epidemics of stem rust can
occur on any of the small grains as a result of spread from barberry.

Races of Puccinia graminis tritici

It can be seen from tables 2, 3, 4, and 5 that 1,063 isolations of 14
races of Puccinia graminis tritdci were made from 735 collections of uredial
material and 95 isolations of 17 races were made from 80 collections of aecial
material. This means that, on an average, a different race was identified in
every 76 uredial isolates (a ratio of 1:76) and a different race was identified
in every 6 aecial isolates (a ratio of 1:6). This shows again, of course, the
role that barberries play in producing and perpetuating physiologic races of
P. graminis. s, r

Despite the fairly large number of races identified, races 56, 38, 17,
19, and 11 combined constituted upward of 95 percent of all the isolates, and the
first three constituted almost 90 percent. For the sixth successive year, race
56' was the most prevalent, constituting 55.5 percent of all the uredial isolates
and 32.5 percent of all the aecial isolates, or about 54 percent of all isolates.
It was isolated from about 80 percent of all uredial collections, which is
somewhat of a decrease in prevalence from that of 1938, when it constituted 66
percent of all isolates and was found in about 83 percent of the collections.
The relative amount of inoculum of race 56 also was somewhat less than in 1938.

sStakman, E. C., and R. C. Cassell. The increase and importance of race
56 of Puceinia praminis tritici (Abs.). Phytopath. 28: 20. 1938.

GStakman, E. C., Lce Hines, Robert C. Cassell, and M. N. Levine. Popu-
lation trends of physiologic forms of Puccinia graminis tritici, 1930 to 1934
(Abs.). Phytopath. 25: 34. 1935.

7Stakman, E. C., R. C. Cassell, and W. Q. Loegering. Population trends
of physiologic races of Puccii graminis tritici in the United States from 1930
to 1939 (Abs.). Phyto~aeh. 30" 22. 1940.






-5-


Race 56, however, was still by far the most prevalent race in North Dakota,
South Dakota, Nebraska, Minnesota, and Iowa, where it was obtained from 92 per-
cent of all uredial collections. This race, as is probably common knowledge,
attacks Ceres and Kota wheats very severely and was responsible for the almost com-
plete elimination of Ceres as a commercial variety in the spring-wheat area.

Race 38, which attacks the soft winter wheats and durum varieties, ranked
second in prevalence, having been identified in 24 percent of the uredial iso-
lates and in 15 percent of the aecial isolates, or 23 percent of all isolates.
Race 38 was particularly prevalent in the eastern part of the barberry-eradica-
tion area, just as 56 was very prevalent in the spring-wheat region and adjacent
Nebraska and Iowa.

The increase in prevalence of race 17, which has been showing a tendency
to increase gradually for a number of years, seems significant. This race com-
prised 3 percent of the uredial isolates in 1938 and 10 percent in 1939. It
was second in prevalence in aecial material, constituting about 19 percent of the
isolates. This race attacks most of the durum and common wheats severely, with
the exception of certain varieties derived from Kanred, among which is Thatcher.

The next most prevalent races were 19 and 11, but each constitutes only
about 3 percent of all isolates. Race 19 behaves much like race 38 but does not
attack Kanred wheat. Race 11 attacks all the differential varieties except the
emmers. None of the other races were present in large amounts. One of the most
conspicuous tendencies during the last few years has been the gradual decrease
of races 21 and 36. It appeared for a time as if race 21 would not appear in
uredial collections, but finally four isolates were obtained, including one
from western North Dakota, where race 36 was also found. It was suspected
that barberries must have been present in the region, and an inquiry was made.
Heavily rusted barberries were found at Sanger, N. Dak., in 1940, and it seems
likely that the collections of races 21 and 36 made in 1939 probably came from
rust developed on these barberries in that year. This is a good example of the
danger of barberries in the prairies and plains region and indicates also that
clues to the existence of barberry bushes may be obtained by race identifica-
tions.

Some other noteworthy facts are given below with respect to uredial iso-
lates.

Race 36, 8 isolates or 0.3 percent.--This race, which has about the same
host range as race 56, was found in areas where we might expect barberries to be
present, as in Minnesota, Missouri, Iowa, and Virginia. One collection from
North Dakota probably originated on the barberries at Sanger as mentioned above.
Two collections were also made in Washington.

Race 147, 8 isolates or 0.8 Dercent.--The distribution of race 147 in
1939 was scattered. It was collected three times in Indiana, twice each in
Ohio and Texas, and once in Pennsylvania (perhaps originating on barberry).
This race behaves like 56 except that it can attack Vernal emmer also.

~AM)






-6


Race 34, 6 isolates or 0.6 -ercent.--This once prevalent race was isolat-
ed in collections from Michigan, Minnesota, Missouri, and Ohio.

Race 49. 6 isolates or 0.6 percent.--Race 49 was isolated once from
material collected in each of the States of Texas, Oklahoma, Kansas, Missouri,
Indiana, and Iowa. It was very prevalent before race 56 became so common and
differs from 56 by being unable to attack Kanred.

Race 59_ 5 isolates or 0.5 percent.--Race 59 was obtained from the five
eastern States of Georgia, Ohio, Pennsylvania, Virginia, and West Virginia.
It attacks only Kubanka, Acme, and Einkorn wheat and is very common in southern
Mexico.

Race 21, 4 isolates or 0.4percent.--One isolate of this race was col-
lected in North Dakota in the same general area in which race 36 was found, and
one was found in each of the States of Wisconsin, West Virginia, and New York.

Race 15, 3 isolates or 0.3 percent.--This race was found in Indiana,
South Dakota, and Wisconsin, It has a wide host range, attacking all the dif-
ferential varieties except Khapli emner wheat.
Race 24. 2 isolates or 0.2 percent.--Race 24 was isolated from Iowa and

Texas collections.

Race 14, 1 isolate or O.1-percent.--Found only in Wisconsin.

North Dakota Uredial Collections

During 1939 a special effort was made to identify the variety of wheat
on which stem rust was collected in North Dakota. These collections are classi-
fied under the heading Df "ounon wheat and barley" and "durum wheat," and the
isolations from each group are given below:

51 collections of c mmon wheat and barley 9 collections of durum wheat

Race No. of Percent of Race No. of Percent of
isolated isolates collections isolated isolates collections
56 51 100.0 38 6 66.7
17 7 13.7 19 5 55.6
38 5 9.8 56 1 1.1
21 1 2.0
36 1 2.0

It is obvious from these figures that race 56 was found on all the com-
mon wheats and barley i lhiCh stem rust was collected in North Dakota. Most of
the collections ir;c!nded in the first group shown above were Ceres, and, as
would be expected, race 56 was isolated from 100 percent of them, while very
little race 56 was obtai,.- rom the durums. From 9 durum collections race 56
was isolated o ly ot -i contrast wiLh 11 isolations of races 38 and 19 from
the same collection. Th. e urumz, as -ay be known, are quite susceptible to
races 38 and 19, while the common sprin, heats are resistant or semiresistant.





-7-


Barber yCollections

Eighty isolations of Puccinia graminis tritici were obtained from aerial
collections in 1939, from which 95 racial isolates were made, representing 17
different races (tables 2 and 5). Races 56, 17, and 38 made up 66.1 percent of
all isolates, representing 32.5 percent, 18.9 percent, and 14.7 percent, re-
spectively. It should be noted that race 17 was more prevalent in aecial col-
lections this year than in 1938, as was also true of uredial collections. Fur-
thermore, race 17 was more common than race 38 in barberry material, while in
uredial collections race 17 occurred less than half as often as race 38. Race
59 was fourth in prevalence in the barberry collections, constituting 6.3 per-
cent, as compared with the relatively low percentage of 0.5 in uredial collec-
tions. It is worthy of note that five of these isolations were made in the
central-western States where race 59 was not obtained from uredial collections.
Other races, 11, 19, 21, 34, 36, and 49, all quite common from field uredial
collections at one time or another, were isolated in a relatively small per-
centage of the collections on barberry. In addition, races 14, 15, 55, 71, 79,
115, and 147 also were isolated. These seldom are found in uredial collections
in the United States; indeed, some of them never have been collected except on
barberry. It is significant, also, that of these seven races, five (15, 55,
79, 115, and 147) attack Vernal.

Races of Puccinia graminis avenae

During the 1939 stem rust survey 440 collections of oats stem rust were
received, including rust on oats, on grasses susceptible to the oats stem rust,
and on barberry (tables 7, 8, and 9). From these, successful inoculations were
made with 250, from which 251 racial isolates were made. From only one col-
lection was more than one race isolated.

As in the past, races 2 and 5 were by far the most prevalent, making up
together 96.8 percent of all isolations. Race 2 was slightly more prevalent,
constituting 55.8 percent compared with 41 percent of race 5. However, these
two races are so similar that they may easily be mistaken for each other, and
therefore for general consideration the difference in percentage is not par-
ticularly significant.

The isolation of races 7, 8, 10, and 12 is interesting. Races 7 and 8
were isolated three times each and 10 and 12 once each. One isolate each of
races 7, 10, and 12 were found in Pennsylvania and came from barberry or near
barberry. The remaining two isolates of race 7 and the three of race 8, how-
ever, were not collected near barberry. They were found as follows:
Race 7 from the Uniform Oat Rust Nurseries in Wisconsin and Oklahoma, and race
8 near Chillicothe, Mo., Springfield, Ohio, and Forest, Wis.

Races of Puccinia graminis secalis

Relatively little stem rust was found on rye in the course of the 1939
survey except in the immediate vicinity of barberries, again emphasizing, as
has been stated frequently, that this rust can be controlled for all practical
purposes by the eradication of barberries.





-8-


As very little attempt has been made to produce rust-resistant varieties
of rye, detailed race identifications of this rust were not made. However,
Puccinia graminis secalis was isolated from three collections of stem rust on
barley, one in Minnesota, one in New York, and one in Pennsylvania. Ralph U.
Cotter identified the race in the latter collection as P. graminis secalis,
race 11. P. graminis tritici, races 56 and 11, also were isolated from this
collection.

General Conclusions

It is eVident from the results of the survey in 1939, especially when
compared with the results of previous years, that the comparative populations of
races of Puccinia graminis tritici may fluctuate considerably. For example,
taking the past 10 years, it is clear that some races such as race 11 have
fluctuated considerably, ranging from 22 percent of all uredial isolates in 1931
to 3.2 percent in 1939. Race 21 was far more prevalent in the first 5 years of
the decade than in the last 5 years. Race 36 ranked first in 1930 and 1931,
with 36 and 28 percent of the isolates respectively; in 1934 it constituted 21
percent; while in 1939 only 0.8 percent of all uredial isolates were race 36.
Race 49 was prevalent during the first 4 years of the decade beginning 1930 and
has shown a tendency to decrease since that time. Race 56 was very scarce in
the first 4 years of the decade, but has ranked first for 6 consecutive years,
the high having been reached in 1938 when it exceeded 66 percent of all uredial
isolates. Race 17 also has shown a tendency to increase, but much more slowly
than 56. Race 34 increased gradually until it reached a maximum of 22 percent
of all uredial isolates in 1934, and since that time it has shown a tendency to
decrease gradually until it was negligible in 1939. Obviously, with a decided
tendency toward population shifts in physiologic races, it is inevitable that
certain varieties that are now quite resistant to rust may rust much more heavily
if certain races increase in prevalence in the future, and the converse also is
true.

As concerns Puccinia graminis avenae, races 2 and 5 have long been by far
the most prevalent races, together constituting 97 percent of all isolates in
1939. The isolation of races 7, 8, 10, and 12 in 1939 indicates that these
races may become more widely distributed and more prevalent in the future.





-9-


Table l.--Varieties of Puccinia graminis isolated from
aecial collections in the United States in 1939


Rust variety


Number of isolates


graminis tritici
graminis secalis
graminis avenae


Total$


Percent

46.2
34.1
19.7

100.0


Table 2.--Physiologic races of Puccinia graminis tritici isolated
from uredial and aecial collections in the United States
in 1939


UREDIAL
No. of
Race isolates Pot.


-AE- CI AL
No. of
Race isolates Pct.


UREDIAL AND AECIAL
No. of
Race isolates Pct.


56
38
17
19
11
36
147
34
49
59
21
15
24
14


590
255
106
35
34
8
8
6
6
5
4
3
2
1


55.5
24.0
10.0
3.3
3.2
0.8
0.8
0.6
0.6
0.5
0.4
0.3
0.2
0.1


56
17
38
59
19
14
15
49
11
21
147
34
36
55
71
79
115


32.5
18.9
14.7
6.3
5.3
3.2
3.2
3.2
2.1
2.1
2.1
1.1
1.1
1.1
1.1
1.1
1.1


100.2


1,063 100.3


Ratio of races to
isolates, 1:75.9


56
38
17
19
11
59
147
36
49
34
15
21
14
24
55
71
79
115


18 1,158


Ratio of races to
isolates, 1:5.6


621
269
124
40
36
11
10
9
9
7
6
6
4
2
1
1
1
1


53.6
23.2
10.8
3.4
3.1
0.9
0.9
0.8
0.8
0.6
0.5
0.5
0.3
0.2
0.1
0.1
0.1
0.1

100.0





- 10 -


Table 3.--Physiologic races of Puccinia Lraminis tritici isolated from aecial and uredial
collections in the United States in 1939, by States


Race and number of times isolated
11 14 15 17 19 21 24 34 36 38 49 55 56 59 71 79115147


Total number
Collec- Isola- Races
tions tions


Colorado
Georgia
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Michigan
Minnesota
Missouri
Nebraska
New York
North Dakota
Ohio
Oklahoma
Pennsylvania
South Carolina
South Dakota
Texas
Virginia
Washington
West Virginia
Wisconsin
Wyoming


Totals


- 2


- 1
- 1 5
- 1 2
- 9

-- 4
- 22
.1 1 16
- 6


- 4
-- 7
1 1 5

- 1 8
- 5
- 1

4
2 1 12


36 4 6 124


. 26
- 1 1 5
3 .- 28

2 1 1 7
- 2 1 20
5 1 1 31

1 1 2
5 1 1 15
2 2 21

4 2 1 21

2 2
8 1 1 25
4 1 10
- 2 -
1 20
3 1 ii


40 6 2 7 9 269


- 2

- 2
- 7
1 32
1 24
1 59

- 25
1 81
1 58
- 34
- 2
-70
- 30
1 23
2 1 25
- 1
- 36
1 41
- 22

- 18
- 25
- 3

9 1 621


- 1 1 -












- 2


2 2



1 1


3 7
3 3
2 2
10 13
43 71
28 40
67 106
2 3
29 41
93 133
83 116
36 51
4 6
81 103
41 62
28 42
56 68
11
40 50
64 89
28 40
2 2
31 46
37 60
3 3


11 1 1 1 10 815 1,158


4
2
1
5
7
10
6
2
7
8
10
4
.4
,6
7
5
14
1
6
9
7
1
6
10
1








1l -


Table 4.--Physiologic races of Puccinia graminis tritici isolated from uredial collections in the
United States in 1939, by States


Race and number of times isolated


State


14 15 17 19


Colorado 1
Cc-.( ia

i L yo is
l.diana 3
Iowa 1
Kansas 6
Kentucky -
Michigan 1
Minnesota 4
Missouri 1
Nebraska 2
New York
North Dakota -
Ohio
Oklahoma 4
lennsylvania 1
South Carolina -
South Dakota -
lexas 5
Virginia 1
Vashington -
'est Virginia 1
Wisconsin 3
Wyoming


Totals


1 3 106 35


21 24 34 36 38 49 50


- 2
- 2

- 3
- 26
1 5
- 28
- 2
- 7
1 18
1 31
'9
-- 2
1 15
- 19
- 7
- 12

- 2
1 25
1 10
2
- 19
- 11


3 -








-- 1

1


4 2 6 8 255


- 2

- 2
- 6
1 31
1 20
1 59
- 1
- 22
- 79
1 56
- 34
- 2
- 70
29
1 23
- 10
- 1
- 36
1 41
- 22

- 17
- 24
- 3

6 590


Total number
59 147 Coliec- Isola- Races


Ciens
3
3
2
7
41L
22
67
2
25
82
80
35
4
81
38
28
20
1
39
64
27
2
23
31
3


5 8 735


tioils
7
3
2

69
31
106
3
37
122
112
50
6
103
59
42
25
1
49
89
2
42

52
3

1,063







- 12 -


Table 5.--Physiologic races of Puccinia graminis tritici isolated from aecial collections
in the United States in 1939, by States


Race and number of times isolated
11 14 15 17 19 21 34 36 38 49 55 56 59 71 79 115 147


Total number
Collec- Isola- Races
tions tions


Illinois
Indiana u
Iowa 2
Michigan
Minnesota -
Missouri
Nebraska
Ohio
Pennsylvania -
South Dakota -
Virginia
West Virginia -
Wisconsin -


- 1


1 1


1 1



1 -


1 1 -. .- . 1 1 . .-
1 -. . . .- 1 . . .-
- . . . . 4 1 1 -
. . .- 1 3 -. . .
4 . . 2 1 2 2 . .
_ 2 -

. . .- 2 1 . . .-
5 4 2 1 9 2 1 15 1 1


1 . .- 1 1 1 -. . .
4 . . . 1 1 1

18 5 2 1 1 14 3 1 31 6 1 1 1 2


95 17


Totals 2 3 3


State






- 13 -


Table 6,--Physiologic races of Puccinia gr4fl4i avenae isolated
from uredial and aecial collections in the United States,
in 1939


URED IAL
No. of
Race isolates Pot,


125
89
3
3
1


221


56.5
40.2
1.3
1.3
0.4


99.7


Race

2
5
12


AEC I AL
No. of
isolates

15
14
1


Pct,

50.0
46.6
3.3


UREDIAL and AECIAL
No. of
Race isolates Pot.


140
103
3
3
1
1


30 99.9 6


55.7
41.6
1.2
1.2
0.3
0.3


251 100.3


Ratio of races to
isolates, 1:44.2


Ratio of races
isolates, 1:10


Table 7.--Physiologic races of Puccinia graminis avenae isolated
from aecial and uredial collections in the United
States in 1939, by States


Race and number
State 2


of times
5 7


isolated


8 10 12 Collections


Total number


I olations


California
Colorado
Florida
Illinois
Indiana
Iowa
Kansas
Louisiana
Maryland
Michigan
Minnesota
Missouri
Nebraska
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
South Dakota
Texas
Wisconsin

Totals


- 11
- 4

- 14
- 40
1 23
- 6
- 13
1 18


i* 1


- 4
- 2
1 1 61
- 5
- 15
- 20


140 103 3 3 1 1 250


* From Uniform Rust Nursery.


Races


11
4
1
1
2
7
11
4
1
14
40
23
6
13
18
4
2
62
5
15
20

251


m






- 14-


Table 8.--Physiologic races of Puccinia graminis avenae isolated
from uredial collections in the United States in 1939,
by States


Race and number of times isolated
State 2 5 7 8 10


Total number


Collections


Isolations


California
Florida
Illinois
Indiana
Iowa
Kansas
Louisiana
Michigan
Minnesota
Missouri
Nebraska
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
South Dakota
Texas
Wisconsin

Totals


- 1

- 1


1 -


- 1


1 -


125 89 3 3 1


Table 9.--Physiologic
from aecial
by States


221


221


races of Puccinia graminis avenae isolated
collections in the United States in 1939,


Race and number of times isolated
State 2 5 12


Total number


Collections


Isolations


Colorado
Indiana
Maryland
Minnesota
Pennsylvania
Wisconsin


14 1 29


Races


Races


Totals 15


30 3












ORIGINAL
INOCULATION
FROM FIELD
COLLECTION r


u z
z lx
_- 4- z I 3c
4 u 0 u z
~ Z U)

0


[ O |1


11 I I I


1F01 ~FaI


#1
I I
I I

~: ~, I1~


1 1 ~1
I I 9 1
91
I I ID ill


'I0
10.


ISOLATE






FIGURE 1. DIAGRAM SHOWING METHOD OF


RACE
17& 19





RACE
56


RACE
19



ISOLATING


RACES FROM A MIXED FIELD COLLECTION


z C
m 4
w I


=?


ISOLATE






ISOLATE
IT





UNIVERSITY OF FLORIDA

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