CEREAL RUST BULLETIN
Report No. 6
June 26, 1996
Issued by:
Cereal Rust Laboratory, Agricultural Research Service,
U.S. Dept. of Agriculture
University of Minnesota, St. Paul, MN 55108
(612) 625-6299 FAX (612) 649-5054
Internet: markh@puccini.crl.umn.edu
CRL web page: http://www.umn.edu/rustlab/
___________________________________________________________________________
* Wheat stem rust has been found in fields in Kansas, Illinois, and
Indiana.
* Trace amounts of wheat leaf rust have spread as far north as central
Michigan.
___________________________________________________________________________
The small grain harvest is underway from southern South Carolina to central
Kansas. In the northern grain -growing area, most the of the small grains
are about 2 weeks behind normal in development and moisture is adequate in
most areas.
Wheat stem rust
During the second week in June, wheat stem rust severities ranged from
trace to 1% in fields of soft red winter wheat in southern Illinois,
southern and northwestern Indiana and in wheat plots in central Indiana at
the soft dough stage. Since the crop is close to maturity, losses to stem
rust will be minimal.
During the second week in June, traces of stem rust were observed in plots
in central and northeastern Kansas. The date of the first stem rust
observation was two weeks later than normal for the northeastern Kansas
location.
The stem rust races identified so far in the 1996 survey (Table 1) were
also identified in 1995. Races QFCS and TPMK were identified from
collections made in mid-April in wheat fields south of Houston, Texas.
Races QCCS and TPMK were identified from collections made in early May in
central Texas.
Wheat leaf rust
During the third week in June, leaf rust was widespread throughout Kansas
on wheat plants where there still was green tissue. Severities ranged from
trace-5% on cultivars in plots and traces in fields in northeastern
Kansas. Rust development was late this year because leaf rust did not
overwinter in Kansas and the climatic conditions were less than ideal for
rust development in early spring.
In mid-June, trace to 15% severities were observed in soft red winter wheat
fields and nurseries at the soft dough stage throughout Indiana and
Illinois. In the third week in June, traces of leaf rust were observed in
fields in the Thumb area and central Michigan. In all of these locations
the leaf rust that developed was from spores that were deposited with rain
from southern inoculum sources and not overwintering sources. Trace
amounts of leaf rust were found in nurseries in southern Minnesota on June
24. Twenty-percent severities were noted on Karl 92 in a nursery in
Lincoln, Nebraska, the third week of June.
Wheat in central Washington is in the late milk to early dough stage.
There are no new developments with leaf rust in that area since the last
bulletin. There was some spraying to control leaf rust on soft white
wheat. An emergency label was obtained for the use of Folicur on wheat in
Washington, because supplies of Bayleton ran low. Leaf rust development in
western Oregon and Washington and northern Idaho were delayed by dry
weather for the first 2 weeks of June, but recent rains have set the stage
for a rapid buildup of leaf rust in that area. Winter wheat in the Palouse
area is not as far along in development as in central Washington, so there
is still time for damage from rust to occur. Growers are watching the rust
development closely and preparing to spray wheat for control of leaf rust
if necessary. The recent rains may have set the stage for a rust outbreak
within 7-10 days. An explosion of leaf rust on the soft white wheat in the
Palouse area is a good possibility.
The leaf rust races identified so far in the 1996 survey (Table 2) were
also identified in previous surveys. The MCD-10 race was identified from
collections made in Louisiana and this was the first time this race was
identified from a cultivar other than Jagger.
Wheat stripe rust
There are no new developments with stripe rust in central Washington since
the last CRB. Growers used lots of fungicide to control stripe rust on the
susceptible varieties of hard red and club wheats. Stripe rust was going
strong on susceptible wheat varieties at Pendleton, Oregon (northeastern
Oregon) last week. Stripe rust development in eastern Oregon and
Washington and northern Idaho were delayed by dry weather for the first 2
weeks of June, but recent rains have set the stage for a rapid rust buildup
in that area. Winter wheat in the Palouse area is not as far along in
development as in central Washington, so there is still time for damage
from rust to occur.
Oat stem rust
There have been no new reports of oat stem rust since bulletin #4. The oat
stem rust races identified so far in the 1996 survey are presented in Table
3. Race NA-27, virulent to Pg-1,2,3,4, and 8 remains the predominant race
of oat stem rust population. Race NA-10, which was isolated from a wild
oat collection made in California, is unusual and has not been found for a
number of years. This race has low virulence and is not a threat to
cultivated oat.
Oat crown rust
By the third week in June, traces of crown rust were found on oats in south
central Wisconsin and in Iowa fields. Traces of crown rust were also
found in south central Minnesota and east central South Dakota plots at
this same time. Crown rust is beginning to build up on susceptible oat
lines near buckthorn, the alternate host, in St. Paul, MN. Recent warm wet
weather should accelerate the increase of crown rust in this area.
Barley stem rust
As of June 26, no barley stem rust has been reported in the U.S. this year.
Barley leaf rust
In early June, traces of barley leaf rust were found in plots in southern
Illinois.
During the second week in June, leaf rust was starting to increase in
winter barley plots in Guelph, Canada, where it likely overwintered.
Because of cool conditions the crop developed late so some damage is
expected in the winter barley crop and damage is likely in spring barley.
Traces of barley leaf rust were found in southern Minnesota plots the third
week in June.
Barley crown rust
Barley crown rust was observed in a Brookings, South Dakota, nursery on
June 17. On susceptible barleys, severities were as high as 15% on all
leaves except for the flag. It is expected that the severities will
increase in the next week or so. Barley crown rust was also found at
severities up to 10% on wild barley, Hordeum jubatum, near buckthorn in St.
Paul, MN.
Barley stripe rust
Stripe rust was extremely severe on winter barley in irrigated plots at
Hermiston, Oregon (north central -northeast part of state) last week.
Peduncles of the very susceptible variety Gwen were covered with telia.
Barley stripe rust has been found on both winter and spring barley
varieties in western Washington for the past 3 weeks (Fig. 2). It is also
present in plots and fields in northern Idaho and was found in plots near
Parma in southwest Idaho. Barley stripe rust was going strong in plots of
spring barley in the Williamette Valley, but there is not much barley grown
in fields in that area. An emergency label was also obtained for use of
Folicur to control stripe rust on barley in Washington, Oregon, and Idaho.
Rye leaf rust
Traces of rye leaf rust were found in southern Minnesota plots the third
week of June.
Stem rust on barberry
The first report of the aecial stage of stem rust found this year on common
barberry, the alternate host, was in southeastern Minnesota in Fillmore
county on June 13.
Crown rust on buckthorn
During the second week in June, light to moderate aecial infections were
found on buckthorn in east central Illinois, southern Minnesota and east
central South Dakota. Due to the cool spring, infections on buckthorn
appeared 2 to 3 weeks later than normal throughout this area. Late-planted
oats in this area will be at risk to crown rust.
In mid-June, aecial development was severe in the Guelph, Canada, area.
The oat crop is very late so crown rust may cause losses.
TABLE 1. Wheat stem rust races identified through June 24, 1996.
__________________________________________________________________
No. of isolates
by state
__________________
Pgt code Virulence formula* TX LA
__________________________________________________________________
QFCS 5,8a,9a,9d,9g,10,17,21 3 0
TPMK 5,7b,8a,9d,9e,9g,10,11,17,21,36,Tmp 14 9
QCCS 5,9a,9d,9g,10,17,21 2 0
QCCJ 5,9d,9g,10,17,21 2 0
__________________________________________________________________
Number of isolates 21 9
Number of collections 7 3
__________________________________________________________________
* Single gene resistances evaluated: Sr5,6,7b,7a,9a,9b9d,9e,9g,10,
11,17,21,30,36,Tmp
TABLE 2. Wheat leaf rust races identified through June 24, 1996.
__________________________________________________________________
Number of isolates by state
____________________________
Prt code Virulence formula* GA LA TX CA
__________________________________________________________________
MBB 1,3 2
MBB-10 1,3,10 1
MBG-10 1,3,10,11 1 2
MBR-10 1,3,3ka,10,11,30 2 5
MCB-10 1,3,10,26 2
MCD-10 1,3,10,17,26 4 2
MGB-10 1,3,10,16 2
MLR-10,18 1,3,3Ka,9,10,11,18,30 2
TBG-10 1,2a,2c,3,10,11 2
TDB-10 1,2a,2c,3,10,24 2
TDG-10 1,2a,2c,3,10,11,24 5
TLG-18 1,2a,2c,3,9,11,18 2
__________________________________________________________________
No. of isolates 1 13 20 2
No. of collections 1 8 12 2
__________________________________________________________________
* Single gene resistance evaluated: Lr1,2a,2c,3,3ka,9,10,11,16,17,
18,24,26,30
TABLE 3. Oat stem rust races identified through June 24,1996.
__________________________________________________________________
No. of isolates by state
__________________________
Race Virulence formula* TX MEX CA
__________________________________________________________________
NA-27 9,13,15,16,a/1,2,3,4,8 22 3 0
NA-16 2,4,9,13,15,16,a/1,3,8 3 0 0
NA-10 1,4,8,9,13,16,a/2,3,15 0 0 4
__________________________________________________________________
Number of isolates 25 3 4
Number of collections 9 2 2
__________________________________________________________________
* Avirulence/virulence.