Cereal Rust Bulletin
Report No. 6
June 20, 2001
Issued by:
Cereal Disease Laboratory
U.S. Department of Agriculture
Agricultural Research Service
University of Minnesota
1551 Lindig St, St. Paul, MN 55108-6052
(612) 625-6299
FAX (651) 649-5054
markh@cdl.umn.edu
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_________________________________________________________________
* Wheat stripe rust is widespread from South Dakota to Indiana.
* Wheat leaf rust is very light this year throughout the U.S.
* Oat crown rust is light in the northern oat growing area.
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Winter wheat harvest has begun from southern Indiana to southern
Kansas. Most of the northern planted spring small grain is well
behind the normal growth stages for this time of the year.
Wheat stem rust. There have been no new reports of wheat stem
rust in the central plains since CRB #5
(http://www.cdl.umn.edu/crb/2001crb/01crb5.html) when stem rust
infections were scattered and light. In early June, severe wheat
stem rust was found in a southern Louisiana nursery on plants
which were planted, much later than the normal, in late January.
Wheat leaf rust. During the second week in June, trace-10% leaf
rust severities were reported in plots and traces in fields of
soft red winter wheat cultivars from northeastern Missouri to
northwestern Ohio (Fig. 1). The cooler than normal temperatures
during the last part of May and first part of June actually slowed
leaf rust development. As stated in CRB #5, this is an abnormally
poor year for leaf rust development throughout most of the U.S.
In mid-June, light leaf rust was observed on the flag leaves of
hard red winter wheats in an east central South Dakota nursery.
By the last week in May, 10-70% leaf rust severities were observed
on susceptible cultivars in a nursery in east central Virginia.
During the second week in June, 10% leaf rust severities were
found on susceptible cultivars at the milk growth stage in
southeastern Washington.
The preliminary leaf rust race identifications and corresponding
virulence formula from collections made in the southern U.S. in
April are presented in Tables 1 and 2. The identified races so
far are not significantly different from the races identified in
the southern U.S. in 2000.
Table 1. Preliminary wheat leaf rust race
identifications through June 19, 2001
Number of isolates
Pt code AL FL GA LA TX VA
MBBJ 1
MBDS 2 7
MCDS 1 8
MBRJ 4
MBRK 4 2 2
MCRJ 2
MDRJ 1 2
NBCR 1
TLGF 2 1
TLGJ 4 2 4
TLGS 2
TLGP 2 4
TLRJ 3
Total isolates 14 4 14 10 17 2
Total collections 8 2 7 5 9 1
Table 2. Pt code and virulence formula
Pt code Virulence formula
MBBJ 1,3,10,14a
MBDS 1,3,10,14a,17,B
MCDS 1,3,10,14a,17,26,B
MBRJ 1,3,3ka,10,11,14a,30
MBRK 1,3,3ka,10,11,14a,18,30
MCRJ 1,3,3ka,10,11,14a,26,30
MDRJ 1,3,3ka,10,11,14a,24,30
NBCR 1,2c,10,18,30,B
TLGF 1,2a,2c,3,9,11,14a,18
TLGJ 1,2a,2c,3,9,10,11,14a
TLGS 1,2a,2c,3,9,10,11,14a,B
TLGP 1,2a,2c,3,9,11,14a,18,B
TLRJ 1,2a,2c,3,3ka,10,11,14a,30
Wheat stripe rust. By mid-June, wheat stripe rust development was
extensive from east central South Dakota to northeastern Indiana
and severities ranged from traces to 80% on flag leaves. The past
two years have seen the most widely dispersed stripe rust
development observed throughout the northern winter wheat area in
at least 40 years. In many of the northern locations rust
severities ranged from trace to 10% and the pustules were large
and producing spores. If conditions stay cool and moist the rust
should continue to increase. In contrast to last year, stripe
rust and leaf rust have not been found together on the same
leaves, which probably indicates they did not develop from the
same spore shower. Much of this stripe rust development
originated from spores produced farther south in Texas, Oklahoma,
Kansas or adjacent states.
On June 8 and 9, light infections of wheat stripe rust were found
in soft red winter wheat plots at Rosemount, and St. Paul,
Minnesota, respectively. Hot temperatures that followed the
initial rust sighting in the Minnesota plots set back the rust
development, but cool and moist weather in mid-June has resulted
in further development.
In early June, stripe rust was severe in irrigated wheat, but
light in dryland wheat in northeastern Colorado.
In mid-June,100% severities of wheat stripe rust were reported on
susceptible winter wheat cultivars in plots in western Washington.
In eastern Washington 40% severities were observed in some fields
of susceptible varieties. During the past two weeks weather
conditions have improved for stripe rust increase in most of the
Pacific Northwest.
Oat stem rust. There have been few reports of oat stem since CRB
#5 (http://www.cdl.umn.edu/crb/2001crb/01crb5.html).
Oat crown rust. There have no new reports of crown rust since CRB
#5
Buckthorn. In the first week in June, infections were light on
buckthorn hedges in southwestern Ontario.
Barley stem rust. No new occurrences of barley stem rust have
been reported in the U.S. since CRB # 5
Barley leaf rust. During the first week in June, leaf rust was
increasing on susceptible barley in southwestern Ontario, but
severities were low because of the cool conditions in late May and
early June.
Stripe rust on barley. In mid-June, stripe rust was severe on
susceptible barley varieties in western Washington and starting to
increase on varieties in eastern Washington fields. During the
past two weeks weather conditions have been good for stripe rust
increase in most of the Pacific Northwest.
Rye leaf rust. In mid-June, traces of leaf rust were reported in
a rye field in northeastern Indiana.
Rye stem rust. There have been no reports of rye stem rust this
year.
Stem rust on barberry. In mid-June, a few aecial infections were
observed on common barberry bushes in south central Wisconsin.