Maataloustieteellinen A ikakauskirja
Vol. 56: 175—182, 1984

Bipolaris sorokiniana on barley seed in Finland

AARNE KURPPA

Department of Plant Pathology, University of Helsinki,
SF-00710 HELSINKI 71, Finland

Abstract. Bipolaris sorokiniana is reported as a common fungus in commercially grown
barley seed in Finland with possible economic importance. In 1974, when 200 samples of
barley seed were surveyed the fungus was identified in 60 per cent of samples. The three fol-
lowing years the incidence was 19, 29 and 38 %. The mean per cent seeds infected was 3.8,
1.3, 1.2 and 1.9 respectively. The highest recorded individual % was 92. The most severely
infected cultivar was Paavo each year. In most cases only the seed cover was invaded by the
fungus but also infection in the embryo and the cell leyers surrounding it was observed. Such
severely infected seeds did not germinate or the seedlings were readily infected after germina-
tion. B. sorokiniana was less frequent in the western parts of the country. Field experiments
in 1972—1979 confirmed the same varietal susceptibility which was found by the survey of
commercial samples of barley seed. High rainfall and relative humidity in July and August
were the main factors associated with increased seed infection incidence.

Introduction

Bipolaris sorokiniana (Sacc. ex Sorok.)
Shoem. (syn. Helminthosporium sativum
Pamm., King & Bakke), perfect state Coch-
liobolus sativus (Ito & Kurib.) Dastur has
a cosmopolitan distribution on many grasses
and cereals and causes serious disease and
economic losses in spring barley and wheat
particularly in warm temperate areas (Spra-
que 1950,Anderson & Banttari 1976). In re-
cent years the fungus has become more fre-
quent in North Western Europe (Jorgensen
1974, Mäkelä 1975, Whittle 1977). The sus-

ceptible crop is readily infected by the fungus
which is able to overwinter in the soil even in
cool climate and because many wild grasses
act as an inoculum reservoir (Jorgensen
1974, Whittle 1977). The diseases the fun-
gus causes are a seedling blight, a foot and
root rot, foliar disease, headblight and
kernel blight (Anderson & Banttari 1976).
Up to 15 % of yield losses have been recently
reported (Whittle & Richardson 1978).
There is no earlier information as to when
the fungus became common in Finland, but
in North Western Europe it happened during
the 1950 s and 1960 s (de Tempe 1964, Jorgen-

Index words: Bipolaris sorokiniana, Hetminslhosporium sativum, Cochliobolus salivas, common root rot; barley,
seed infection

175

JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND

https://www.c-info.fi/en/info/?token=tlj4lQn9SSJwrI4x.3OkJRMM2WBY4nc3Pr8zDTw.3H06WMS_vVOHBq9F-HNeu80f4b8z0OzuAEoE6rCEXHm8H6W_3oUC-NNVapYnJE2uaKMK3dHmlv3iAqN50PQ3wxxNAg1xUX6c_6aesSestoYRZBFB6WF9ps_v7PtOWI0zfrDmz0YV9ZMMLpL09tX1lkgyxZ7JABGigiQ


sen 1969, Hewett 1975). A later report of
Kurppa (1982) assumes the fungus gaining
still increasing importance as a pathogen of
spring barley in Finland.

Materials and methods

During the years 1972 to 1979, 11—l9
spring barley cultivars grown in field experi-
ments at the University Farm at Viikki were
examined each year for the presense of Bipo-
laris sorokiniana. Experimental seed samples
from North Savo Experimental Station,
Maaninka were examined during 1972 and
1973. 649 commercial samples of spring bar-
ley, including those most commonly sown
were taken from those seed lots received
annually at the State Seed Testing Institute,
Helsinki for testing for purity and germina-
tion.

Representative sub-samples of 100 seeds
were placed in petri dishes (diameter 14 cm),
50 each on wet filter paper and cotton filter.
The dishes were incubated at 20—22°C for
six days and then examined for fungal
growth. B. sorokiniana could be readily
identified with a stereo microscope at the
magnification of 12 to 50 times if it was pre-
sent in germinating seeds.

The fungi belonging to the other genera
were also recorded. The seed lots with high
incidence of seed infection were further exa-

mined for possible embryo infection. The
seeds were cut into two halves and one half
was placed in a petri dish as described above
and the other half was discarded. One hun-
dred seeds were examined per a sample. The
seed halves were observed after three days of
incubation for the localization of the site of
infection. During the short incubation time
no growth from the seed cover could reach
the embryo area, but any fungal growth
within the embryo could be easily seen.

Preliminary tests of seed infection inci-
dence included a treatment with 1 % Na-
hypochloride solution. Comparison of test
results with and without this treatment
showed no significant differences and the
treatment was discontinued.

The weather conditions during the rese-
arch period:

The growing seasons 1972—1975 were
warmer and seasons 1976—1978 cooler than
average. The temperature during the 1979
season was near average. Summers in 1973
and 1975 were very dry and 1976, 1977 and
1979 were abnormally rainy. The precipita-
tion during late summer 1974 was also high
(Anon 1972—1979).

Results

The incidences of Bipolaris sorokiniana in
spring barley seed varied marketly during the

Fig. 1. A barley seed sample cv. Paavo with very high
incidence of Bipolaris sorokiniana after 5 days of incu-
bation in a petri dish.

Fig. 2. A seed half with severe embryo infection by the
fungus after 4 days of incubation.

176



177

research period 1972—1979. In certain years
the fungus was widespread occuring with
high levels in susceptible cultivars. Overall
figures for seed infection show the fungus
was common but associating with certain
cultivars. In the seed samples from field ex-
periments at University Farm, Helsinki Viik-
ki, the fungus was very common in 1972 and
1974 but did not occur at all in 1973 and
1975. From low to moderate incidences were
recorded in the following years (Table 1).
During dry seasons the infection status of the
sowing seed did not have any effect on the
infection incidence of new grain yield, but
during moist seasons the crop grown from
infected seed served as an important source
for spore liberation for secondary infection.

Fungal growth in individual seeds was
mostly superficial and the fungal hyphae had Table

1.

The
occurenceof

Bipolaris
sorokiniana
in
grain
yield
of

different
spring

barley
cultivars
from
field
experiments
at

University
Farm,
Viikki
during
1972

—1979.

=

cultivar
not
in

experiments.

Per
cent

seeds
infected

Two-row
cultivars

Six-row
cultivars

Cultivar
1972
1973
1974
1975
1976
1977
1978
1979

Cultivar
1972
1973
1974
1975
1976
1977
1978
1979

Aapo Arvo

26

0

1

Etu

16

0

14

0

0

2

0

0

Birgitta
20

0000356
Hja-673

Eva— Gunilla
2

0

0

0

Ingrid Kajsa

_______2Pomo
12

0

0

1

1

3

0

Karri

16

0

12

0

0

0

2

2

Suvi

Mari

29

0—
00442

Tammi
14

0—
0

0

Teemu Vigdis

0

17

02444

Yearly mean
18.6

0.0

4.8

0.0

0.4

1.5

5.3

3.7

24.5

0.0

11.6

0.0

0.3

2.5

2.4

2.4

Fig. 3. The regional distribution of the seed samples.
See Table 3.



only invaded the seed coat. In 1972 severe in-
fection of embryos or the surrounding layers
was detected in many cultivars, particularly
cvs Paavo, Mari and Birgitta. The highest in-
dividual percentage of embryo infection was
recorded with cv. Paavo at 32 %. The other
common fungus species recorded each year
with the survey were Alternaria sp., Cepha-
losporium sp., Cladosporium sp. and Uloc-
ladium sp.. Also Fusarium species were com-
mon after rainy late growing seasons like
1972 and 1974. A survey of spring barley cul-
tivars at North Savo Experimental Station,
Maaninka 1972 revealed the following inci-
dence of B. sorokiniana in seed samples (%):

Balder 10, Etu 13, Karri 9, Lise 0, Mari 10,
Paavo 8, Pirkka 0, Pomo 31, Olli 0, Otra 6
and Vigdis 19. Severe infection of the
embryo was detected with the cvs Porno and
Vigdis with an incidence of 10 %. The fol-
lowing summer the mean percent infected
seeds of cv. Vigdis was 60.0.

According to surveys of commercial sam-
ples of spring barley in 1974—1977 B. soro-
kiniana was a common and widespread fun-
gus throughout the country, wherever barley
is grown (Table 2). In 1974, when the fungus
was exceptionally common, several samples
with high incidence of seed infection were re-
corded. Differences in the incidence were
also found between the cultivars. Each year
the highest levels occurred in cv. Paavo. All
these samples with high B. sorokiniana inci-
dence were also severely infected in the
embryos.

Clear differences in incidence between
geographic areas could not be found, but it
seems obvious that fungus is less frequent in
Western and South Western parts of the
country (Turku and Pori and Vaasa coun-
ties) (table 3).

Discussion

These surveys and other earlier observa-
tions of Bipolaris sorokiniana occuring in

barley crop by Mäkelä (1971, 1972, 1975)
and barley seed by Kurppa (1975) show deci-
cively the incidence of the fungus in barley in
Finland.

The infection incidence was clearly asso-
ciated with certain cultivars as also reported
by de Tempe(l964), Kietreiber (1973, 1974)
and Whittle (1977). The true susceptibility
to seed borne infection is related to the inva-
sion to the seed by the fungus as reported by
Anderson and Banttari (1976). Superficial
invasion is effectively controlled by the use
of mercurial seed treatment but infection in
the embryo or the surrounding cell leyers is
not controlled.

Differences in the disease incidence and
fungal incidence have also been reported
between areas and years by Jorgensen

(1969) and Kietreiber (1973, 1974) and these
are strongly related to the weather conditions
as shown by Couture and Sutton (1977).
The higher incidence in central part of the
country rather than in the coast area is asso-
ciated to higher relative humidity and after-
noon showers which are more frequent out-
side the coast area during the critical period
of seed ripening.

No regional differences in disease inci-
dence could be found associated to sowing
seedbecause commercially distributed seed is
mainly used for sowing. Seed dressing to
control the pathogen is increasingly impor-
tant because it also helps to prevent the accu-
mulation of the fungus as a destructive soil
borne pathogen. This is particularly true
after rainy growing seasons.

The most important factor in seed infec-
tion is the location of the fungus in the seed,
either in the seed coat or in the embryo.

Acknowledgements. The State Seed Testing Institute
is acknowledged for providing research material. Spe-
cial thanks are due toprofessor Eeva Tapio and Dr. Kai-
ho Mäkelä for the support and good advice they have
given me in my work. I also wish to thank Dr. Randall
Kelley for linguistic revision of the English text.

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179

Table
2.

The
occurenceof

Bipolaris
sorokiniana
in

commercial
samples
of
spring
barley
examined
yearly
during
1974

—1977.

Number
of
samples

Per
cent

samples

Per
cent

seeds

The
highest

recorded

examined

infected

infected

individual
%

Cultivar

1974
1975
1976
1977

1974
1975
1976
1977

1974
1975
1976
1977

1974
1975
1976
1977

Six-row
cvs

Eero

0

2

6

13

0.0

0.0

23.0

0.0

0.0

0.0

2

Etu

H

4

4

9

63.7
25.0
25.0
56.0

4.6

2.7

1.0

1.6

27

11

4

4

Hja-673

3

8

33

25

100.0
13.0

27.0
20.0

4.0

0.1

0.8

0.8

6

14
10

Otra

59

30

54

34

38.0
7.0

11.0
41.2

1.0

0.1

0.2

1.1

7

13
7

Paavo

5

8

6

5

100.0
88.0
67.0

100.0

47.4
11.8
12.8
17.4

92

45

35

58

Pirkka

23

14

16

9

48.0
21.4
37.5
55.6

1.1

0.4

1.2

1.7

9

3

6

4

Pomo

21

18

25

18

85.7
11.1

55.6
27.8

3.2

0.2

1.6

1.1

10

2

8

8

Suvi

18

10

5

4

100.0
20.0
60.0
75.0

4.4

0.3

1.2

2.7

9

2

2

6

Teemu

0

0

3

4

0.0
100.0

0.0

3.8

6

Two-row
cvs

Birgitta

2

0

0

0

100.0

34.0

63

Eva

0

4

9

10

50.0
44.4
50.0

0.8

0.8

3.0

2

3

21

Ingrid

18

6

4

4

66.7
16.7

0.0

25.0

2.1

0.2

0.0

0.8

11

1

0

3

Karri

37

19

7

9

70.0
15.8

28.6
33.3

2.6

0.9

0.7

1.5

12

12

4

9

Mari

3

10
0

66.7
0.0

9.7

0.0

22

0

Yearly
number

of
samples examined

200

126

173

150

Mean
per
cent

of
samples
and

seeds
infected

60.0
19.0

28.9
38.0

3.8

1.3

1.2

1.9



Table 3. The regional occurence of Bipolaris sorokiniana in Finland during the growing seasons 1974—1977 as
determined by a survey of commercial samples of spring barley.

Number of samples examined Per cent samples infected

County 1 1974 1975 1976 1977 1974 1975 1976 1977

1 Turku and Pori 57 43 72 63 62.6 20.9 26.4 23.8
2 Uusimaa 31 24 31 15 62.5 16.7 45.2 46.7
3 Kymi 27 11 24 13 66.7 18.2 29.2 84.6
4 Häme 30 15 6 20 65.9 13.3 16.6 35.0
5 Mikkeli 11 1 1 2 71.4 (100.0) (100.0) (50.0)
6 Vaasa 22 20 27 26 43.5 10.0 11.1 34.6
7 Central Finland 6 0 5 8 83.3 60.0 62.5
8 Kuopio 13 5 5 3 76.9 20.0 40.0 66.7
9 Northern Karelia 2 0 0 0 (0.0)

10 Oulu 17 2 0 (100.0) 42.8 (50.0)

Total number of
samples examined 200 126 173 150

Mean per cent samples
infected 63.0 19.0 28.9 38.0

1 See fig. 3.

References

Anderson. W.H. & Banttari, E.E. 1976. The effect of
Bipolaris sorokiniana on yield, kernel weight and
kernel discoloration in six-row spring barleys. PI. Dis.
Reptr, 60: 754—758.

Anon. 1972—1979. Kuukausikatsauksia Suomen sää-
oloihin. Touko-elokuu 1972—1979. Ilmatieteen lai-
tos.

Couture, L. & Sutton, J.C. 1978. Relation of weather
variables and host factors to incidence of airborne
spores of Bipolaris sorokiniana. Can. J. Bot. 56:
2162—2170.

Hewett, P.D, 1975. A health survey of seed barley. PI.
Path. 24: 229—232.

Jorgensen, J. 1969. Species of Fusarium and Hel-
minthosporium on seed of barley grown in Denmark
during 1965—1967. Acta Agric. Scand. 19; 92—98.

—, 1974. Occurence and importance of seed borne ino-
culum of Cochliobolus sativus on barley in Denmark.
Acta Agric. Scand. 24: 49—54.

Kietreiber, M. 1973. Tätßer 1972. Geshundheits-
zustand der Saatgutproben. Jb. 1972 Bundesanst.
Pflßau. Samenpruf. Wien, 59—73.

—, 1974. Tätßer 1973. Geshundheitszustand der Saat-
gutproben. Jb. 1973 Bundesanst. Pflßau. Samen-
pruf. Wien, 65 —78.

Kurppa,A. 1975. Ohran tyvi- ja lehtilaikku yleistyvä
piilevä kasvitauti. Käytännön Maamies 1975, 7:
20—21.

—, 1982. Sienituhoja siemenviljassa. Pellervo 1982, 8:
30—31.

Mäkelä, K. 1971. Some graminicolous species of Hel-
minthosporium in Finland. Karstenia 12: 5—35.

—, 1972. Leaf spot fungi on barley in Finland, Acta
Agr. Fenn. 124; 1 —23.

—, 1975. Occurence of Helminthosporium species on
cereals in Finland in 1971—1973. J. Sci. Agric. Soc.
Finl. 47; 181—217.

Spraque, R. 1950. Diseases of cereals and grasses in
North America. 538 p. New York.

Tempe, J.de. 1964. Helminthosporium spp. in seeds of
wheat, barley, oats and rye. Proc. Int. Seed Test.
Assoc. 29: 117—140.

Whittle, A.M. 1977. Cochliobolus sativus on barley in
Scotland. PI. Path. 26: 67—74.

—, & Richardson, M.J. 1978. Yield losses caused by
Cochliobolus sativus on Clermont barley. Phytopath.
Z. 91: 238—256.

Ms received June 29, 1984

180



SELOSTUS

Bipolaris sorokiniana-sienen esiintyminen
ohran siementavarassa Suomessa

Aarne Kurppa
Helsingin yliopiston kasvipatologian laitos,
00710 Helsinki 71

Bipolaris sorokiniana (syn. Helminthosporium sati-
vum, koteloaste Cochliobolus sativus) todettiin yleiseksi
ja potentiaalisesti haitalliseksi sieneksi ohran siementa-
varassa vuosina 1972—1979 Helsingin yliopiston kasvi-
patologian laitoksella suoritetuissa tutkimuksissa. Vuo-
sina 1974—1977 tutkittiin 649 siementavaraksi tarkoi-
tettua ohraerää, joista sienen tartuttamiksi todettiin ai-
kajärjestyksessä 60, 19, 29 ja 38 %. Infektoituneita jy-
viä oli vastaavasti keskimäärin 3.8, 1.3, 1.2 ja 1.9 %

tutkituista. Lajikkeiden välillä oli selviä alttiuseroja,
Paavo oli infektoitunein kaikkina vuosina ja yleisesti
viljelty Otra tervein. Selviä eroja kaksi- ja monitahois-
ten lajikkeiden alttiudessa ei todettu. Sientä esiintyi
maan länsiosissa jonkinverran vähemmän kuin muu-
alla.

B. sorokiniana esiintyi useimmiten rihmastona sie-
raenkuoressa, mutta monissa tapauksissa se oli infektoi-
nut myös alkion ja sen läheiset solukerrokset, mikä ai-

heutti siemenen itämättömyyden tai oraan sairastumisen
heti itämisen jälkeen.

Vuosina 1972—1979 tutkittujen kenttäkokeiden sato-
näytteiden tulokset tukivat otannalla saatuja tuloksia.
Koska sieni infektoi jyväsadon sekundäärisesti tuulen
mukana leviävien kuromien välityksellä, sen runsaus
siemenissä kytkeytyi erityisesti heinä- ja elokuun sade-
määriin, suhteelliseen ilmankosteuteen ja myös kasvus-
tojen lakoisuuteen. Erityisen kuivissa olosuhteissa sieni
ei infektoinut kypsyvää jyväsatoa lainkaan.

Sienen todellinen merkitys siemenlevintäisenä taudin-
aiheuttajana riippuu jyvien infektoituneisuusasteesta;
onko sieni vain siemenkuoressa, vaiko myös alkiossa.
Pelkän siemenkuoritartunnan saanut kylvösiemen voi-
daan puhdistaa tehokkaasti taudinaiheuttajasta eloho-
peapitoisella valmisteella peittaamalla. Toimenpide ra-
joittaa osaltaan myös sienen lisääntyvää haitallisuutta
maalevintäisenä taudinaiheuttajana.

181