Stripe
Rust Update, May 23, 2012
excerpts from Dr. Xianming
Chen's Report
Wheat
Stripe Rust in eastern Washington and eastern Oregon
Yesterday,
I was checking wheat fields in Whitman, Columbia, Walla Walla, Benton,
Franklin, and Adams counties of Washington and the Pendleton and Hermiston
areas in Umatilla county of Oregon. Winter wheat ranged from late
jointing (Feekes 9) to flowering (Feekes 10.5) with most fields at boot (Feeks
10) to heading (Feeks 10.2). Spring wheat ranged from not emerged to
early jointing stage (Feekes 4). In Walla Walla Co., stripe rust was
found about four out of ten fields. However, the disease developed to 40%
severity in susceptible spreader rows and some entries in our stripe rust
monitoring nurseries near Walla Walla, where stripe rust was found to be just
started a month ago. In Umatilla Co., stripe rust was found in two fields
near Milton and one field near Pendleton and was not found in about other four
or five fields checked. Very low levels of stripe rust was found in
fields of Pendleton and Hermiston stations. Overall, the incidences (less
than 1% to 5%) and severity (1 to 10%) of stripe rust were low. Most
infected leaves are upper leaves with just a single stripe, and only one
hotspot of 1 foot in diameter with infection from the bottom to the top was
found in a field with plants at flowering stage north of Walla Walla,
indicating overwintering.
Other
Problems
Physiological
leaf spot (PLS) was a common problem in winter wheat fields in Columbia, Walla
Walla, and Umatilla counties. Crown rot was severe in Horse Heaven
Hills. Barley yellow dwarf (BYD) was common in early planted
fields. Some fields had herbicide damage. These problems caused
spots (PLS), yellowing or dead leaves (crown rot, BYD, herbicide damage) in
patches or stripes in fields, which can be confused with stripe rust in
distance. Please make sure to distinguish them from stripe rust as
fungicides controlling stripe rust have no effect on these problems.
Weather
Conditions Related to Stripe Rust
The
current stripe rust pressure is relatively low, compared to the same time of
both 2010 and 2011, but will increase quickly during the next two to three
weeks based on spore availability and weather conditions in the last three
weeks and forecasted for the next 10 days. The average temperature in May
so far has been and is predicted for the entire May to be lower than normal
(more favorable for infection and little bit less favorable for producing
spores), but the precipitation has been and is predicted to be lower than
normal in May (less favorable for infection). However, the widespread
rains and showers this week should increase stripe rust infection. The
low temperatures this week and forecasted for next week are not high enough for
high-temperature adult-plant (HTAP) resistance to work at its best.
Recommendation
for Control of Stripe Rust
Winter
wheat.
As winter wheat in most fields are approaching flowering stage, from now to
next couple of weeks will be critical for fungicide application. The
previous general recommendation remains the same for wheat cultivars in
different reaction categories. The following winter wheat cultivar in the
susceptible or moderately susceptible categories may need fungicide spray:
- AgriPro Paladin,
- Eddy,
- Esperia,
- Whetstone,
- Declo,
- WB-Tucson,
- AP Legacy,
- Tubbs 06,
- UICF Brundage (CLEARFIELD®),
- Boundary,
- Mary (OR2040726), and
- Xerpha.
- Norwest 553,
- Legion,
- Madsen,
- Skiles,
- Bruehl,
- Cara,
- Chukar, and
- Coda.
- Bauermeister,
- Finley (used to be susceptible, but was resistant in the last two years due to race changes, better to spray this year),
- MDM,
- UICF Grace,
- UI Silver,
- AP700 CL (CLEARFIELD®),
- ARS-Amber (ARS960277L),
- Brundage 96,
- Bruneau,
- Eltan,
- Masami,
- ORCF-102 (CLEARFIELD®),
- ORCF-103 (CLEARFIELD®),
- Rod,
- Stephens,
- WB-528,
- ARS-Chrystal, and
- ARS-Crescent.
Spring
wheat.
Early planted spring wheat is approaching the stage for herbicide
application. For susceptible and moderately susceptible cultivars (Nick,
Hank, Tara 2002, Macon, Otis, Alpowa, Babe, Bullseye, Hollis, Jefferson, and
Westbred 926), it may be better to spray with fungicide together with herbicide.
For resistant and moderately resistant cultivars (JD, Clear White, Diva,
Louise, Wakanz, Whit, Eden, Buck Pronto, Kelse, Scarlet), it may be unnecessary
to spray with fungicides.
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