Agriculture Reference
In-Depth Information
Table 5.2
Optimal temperatures for infection and growth, areas of distribution, and alternate hosts of
Puccinia triticina
(wheat leaf rust),
P. striiformis
f. sp.
tritici
(wheat stripe rust), and
P. graminis
f. sp.
tritici
(wheat stem rust) in the US.
Infection temperature
Growth temperature
Distribution in US
Alternate hosts
Puccinia triticina
15-25 °C
20-30 °C
Common and widespread in
Great Plains, southeastern
US, Ohio Valley;
Lower incidence in northeast
and Pacifi c Northwest
Thalictrum
speciosissimum
—
present in southern
Europe—not native
to North America
Puccina striiformis
f. sp.
tritici
10-12 °C
13-16 °C
Common and widespread in
Pacifi c Northwest,
California, and Gulf Coast;
can be common and severe
in southern and mid-Great
Plains; lower incidence in
northern Great Plains and
northeastern US
No alternate host
found
Puccinia graminis
f. sp.
tritici
15-24 °C
25-35 °C
Overwinters in south Texas
and Gulf Coast; infections
found on susceptible wheat
in Great Plains and
southeastern US; historically
most destructive in spring
wheat area of Great Plains
Berberis vulgare
—
once common and
widespread—
currently present in
low numbers in
Great Plains and
Pacifi c Northwest
relative of common wheat, such as emmer wheat
or a grass in the tribe Triticeae. It is not known
when stem rust was fi rst established in wheat in
North America. Both wheat and susceptible
Ber-
beris
spp. were introduced by early settlers, and
the pathogen could have been introduced through
imported
Berberis
spp. that had stem rust infec-
tions, or urediniospores and teliospores on wheat
or barley straw, or urediniospores attached to
clothing and implements. The capability of stem
rust urediniospores to survive in transcontinental
air currents indicates that the introduction could
also have been a natural event.
In the early 1900s stem rust epidemics were
frequent in the north central US and Manitoba
and Saskatchewan in Canada, since all bread
wheat cultivars were susceptible and millions of
barberry plants were present in the Great Plains
region. Only durum cultivars had some resistance
to stem rust. Severe epidemics occurred in 1904,
1916, 1919, 1923, and 1927. The 1916 epidemic
is especially notable since the large yield losses
spurred the national barberry eradication program
in the US (Campbell and Long 2001). In 1919
losses of 20% in spring wheat occurred in North
Dakota and Minnesota, and 10% losses occurred
in the winter wheat grown in Nebraska and
Kansas. Even after the release of stem rust resis-
tant spring wheat cultivars, severe epidemics with
losses over 50% occurred from 1935 to 1937 and
1950 to 1954 due to the emergence of virulent
stem rust races (Kolmer 2001b; Leonard 2001). A
sustainable wheat industry could be maintained
in the Great Plains of North America only if stem
rust resistant cultivars were widely grown in both
the winter wheat and spring wheat regions. Since
the 1950s epidemics, the incidence of stem rust
has been greatly reduced, a cumulative result due
to the effect of barberry eradication in reducing
the number of stem rust races (Leonard 2001) and
the widespread planting of stem rust resistant
spring wheat and winter wheat cultivars through-
out the Great Plains region. Stem rust is virtually
nonexistent today in production fi elds, and is seen
almost exclusively in plots of susceptible winter
and spring wheats.
