Septoria and Stagonospora Diseases of Cereals - CIMMYT ...

Septoria/Stagonospora Leaf Spot Diseases on Barley in
North Dakota, USA
J.M. Krupinsky1 and B.J. Steffenson2 (Poster)
1 USDA, Agricultural Research Service, Northern Great Plains Research Laboratory, Mandan, ND, USA
2 Dept. of Plant Pathology, North Dakota State Univ., Fargo, ND, USA
Abstract
Diseased barley leaves were collected from fields in North Dakota in 1998. The most common Septoria/Stagonospora
diseases were septoria speckled leaf blotch (Septoria passerinii) and stagonospora avenae leaf blotch (Stagonospora
avenae f. sp. triticea). Net blotch (Drechslera teres) and spot blotch (Bipolaris sorokiniana) were also commonly
present. Stagonospora nodorum blotch (Stagonospora nodorum) and tan spot (Drechslera tritici-repentis), which are
major diseases on wheat in the area, were detected on barley but at rather low levels. When isolates of S. nodorum from
barley were tested on wheat and barley in greenhouse inoculations, higher symptom severity ratings were obtained on wheat
compared to barley, indicating that the isolates obtained from barley were probably wheat-type isolates. Because of the
importance of both Septoria passerinii and Stagonospora avenae f. sp. triticea on barley, selecting barley for Septoria/
Stagonospora resistance will require screening with both organisms.
Barley (Hordeum vulgare L.) can
be affected by a number of plant
diseases that can cause economic
losses in yield and quality. The
Septoria/Stagonospora diseases
common on barley are septoria
speckled leaf blotch (Septoria
passerinii Sacc.), stagonospora
avenae leaf blotch (Stagonospora
avenae Bissett f. sp. triticea T.
Johnson [syn. Septoria avenae A.B.
Frank f. sp. triticea T. Johnson]), and
stagonospora nodorum blotch
(Stagonospora nodorum [Berk.]
Castellani & E.G. Germano [syn.
Septoria nodorum {Berk.} Berk. in
Berk & Broome]) (Kiesling, 1985;
Mathre, 1997). Barley-type isolates
of S. nodorum have also been
identified (Cunfer and Youmans,
1983; Smedegard-Peterson, 1974). A
cooperative survey was undertaken
to determine the importance of
Septoria/Stagonospora leaf spot
diseases common on barley in
North Dakota.
Materials and Methods
Diseased barley leaves (green
leaves with leaf spots) were
gathered from naturally-infected
barley plants in the field in 1998.
Leaves were collected from 70
fields located in the southwestern,
central, northeastern, and eastern
areas of North Dakota. Collected
leaves were dried and stored dry at
4C in a refrigerator until processed.
Leaf sections, 2 cm long, from
approximately 8 leaves per
collection, were processed. Leaf
sections were surface-sterilized for
3 min in a 1% sodium hypochlorite
solution containing a surfactant,
rinsed in sterile distilled water,
plated on 2% water agar in plastic
Petri dishes, and incubated under a
12-h photoperiod (cool-white
fluorescent tubes) at 21C. After 7
days, leaf sections were examined
for fungi. Pycnidiospores from
pycnidia on the leaf sections were
identified microscopically. The
presence of Drechslera teres (Sacc.)
Shoemaker, Bipolaris sorokiniana
(Sacc.) Shoemaker, and D. tritici-
37
repentis (Died.) Shoemaker was also
noted. Two to four fungal species
were present on some leaf sections.
Isolates were obtained, grown,
stored, and inoculum was prepared
as described by Krupinsky (1997).
Nine isolates of S. nodorum
obtained from barley were
compared in glasshouse
inoculations of wheat and barley
seedling plants. Two wheat
cultivars, Eureka and Fortuna, and
two barley cultivars, Bowman and
Hector, were used. In a glasshouse,
seedlings were planted, grown,
fertilized, inoculated, incubated,
and assessed for percentage
necrosis of the first leaf as
previously reported (Krupinsky
1997).
Results and Discussion
Of the 531 leaf sections
processed, 45% were infected with
S. passerinii, 37% with S. avenae f.
sp. triticea, and 14% with S.
nodorum. Drechslera teres, B.
sorokiniana, and D. tritici-repentis