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Wheat & Small Grains Stripe Rust Update 2017

Stripe Rust Update – July 2017

Rust Update, July 11, 2017

Xianming Chen

  1. Rusts in the Palouse Region

We were checking fields of wheat and barley in the Palouse region (including Whitman County of Washington and Latah County of Idaho) on July 7, 2017.  Winter wheat crop ranged from soft dough to almost mature, spring wheat crop from boot to milk, and spring barley from headed to milk.  The rust situations are the following.

Wheat stripe rust.  Active stripe rust pustules were still found on green leaves of some winter wheat fields in both commercial and experimental fields.  For spring wheat, stripe rust reached 100% on susceptible varieties in experimental fields around Pullman.  In commercial fields, stripe rust was low, less than 1% incidence and up to 10% severity in most fields checked.  The low level of stripe rust in commercial fields is due to cultivar resistance and/or application of fungicides in the early season.  With the dry and hot weather conditions in the last couple of weeks and similar weather conditions forecasted for the next two to three weeks, HTAP resistance in many spring wheat cultivars has become effective and stripe rust development will be slowed down or stopped.  Except fields of very late crops and still have good soil moisture, fungicide application is no longer needed.

Barley stripe rust.  Low to moderate levels of barley stripe rust were observed in experimental fields.  In commercial fields, stripe rust was found at very low level in only one barley field in Latah County.

Wheat leaf rust.  In monitoring and variety trial nurseries, leaf rust was found in plots of several winter wheat.  In commercial fields, leaf rust was also found in several winter wheat fields near Farmington in Washington and Potlatch in Idaho.  Incidence was less than 1% and severity less than 10%.  No leaf rust was found in any spring wheat fields.

Stem rust.   No stem rust was found in any of winter and spring wheat fields, and nor in barley fields.

  1. Rusts in Western Washington

In our experimental nurseries at Mount Vernon in western Washington, wheat stripe rust reached 100% severity on susceptible spring wheat by the end of last week.  Barley stripe rust was up to 60% severity.  Wheat leaf rust was low.  In contrast to the situations of severe barley leaf rust in the recent years, barley leaf rust was much lower this year, which could be due to the relatively late planting.

  1. Wheat Stripe Rust in the US and Canada

Wheat stripe rust has been reported in Texas, Louisiana, Arkansas, Mississippi, North Carolina, Oklahoma, Kansas, Washington, Oregon, Wisconsin, Virginia, Delaware, Tennessee, Michigan, Kentucky, Nebraska, Indiana, Georgia, Idaho, Arizona, California, Montana, Colorado, South Dakota, Minnesota, North Dakota, and New York.  Wheat stripe rust has been reported in Alberta, Ontario, Manitoba, and Saskatchewan provinces of Canada.

View the July 2017 Stripe Rust Update in pdf format.

Stripe Rust Update – June 2017

Stripe Rust Update June 16, 2017

Xianming Chen

  1. Wheat Stripe Rust

In the Pacific Northwest, winter wheat in most areas has passed the flowering stage.  Thanks to planting of resistant varieties and widely use of fungicides in the early season with some fields sprayed twice, stripe rust in most fields of winter wheat is under control.  Depending upon areas and various times of planting, spring wheat crop varies from Feekes 4 to Feekes 10.5.3.  Stripe rust has developed rapidly in spring wheat fields with severity on susceptible varieties ranging from 5% to 100% depending upon area and planting date.

Because the cooler weather and good moisture in this week, stripe rust will likely develop more in the next couple of weeks. For fields of moderate susceptible and susceptible varieties (stripe rust ratings 5 – 9) of winter wheat, fungicide application is needed if the crop has not passed Feekes 10.5 and fungicide was applied more than two weeks ago.  For spring wheat, fungicide is needed at the time of herbicide application for fields planted with moderately susceptible and susceptible varieties if not done so.  For fields of fungicide applied about three weeks ago, another application is needed.  For varieties previously reported to be resistant to moderately resistant (ratings 1-4), check fields and consider fungicide application if active rust pustules are seen and severity reaches 5%.

We took stripe rust notes in our experimental fields of spring wheat on June 15, most plants passed the flowering stage and the susceptible check had 100% severity. Table 1 shows the data and ratings for the spring wheat variety trials for reference.  As these data were from only Lind and rust races can be different in different areas, use these data together with the data from the last year for considering to use or not to use fungicides.

Since the last report on May 19, wheat stripe rust has been reported in South Dakota, Minnesota, North Dakota, and New York in addition to the previous reports in Texas, Louisiana, Arkansas, Mississippi, North Carolina, Oklahoma, Kansas, Washington, Oregon, Wisconsin, Virginia, Delaware, Tennessee, Michigan, Kentucky, Nebraska, Indiana, Georgia, Idaho, Arizona, California, Montana, and Colorado.  Wheat stripe rust has been reported in Alberta, Ontario, and Manitoba provinces of Canada.

  1. Barley stripe rust

In our spring crop nurseries at Lind (Adams County, WA), stripe rust was uniform on susceptible varieties with severity up to 40%.  For this dryland area, this is the most severe barley stripe rust we have seen in the last 20 years, partially due to the 6-inch higher-than-average precipitation this year, although much lower than wheat stripe rust in this location.  Barley stripe rust has not been observed in the Palouse region yet.  In addition to Washington, barley stripe rust has been reported in California and Oregon.

Fungicide application may be needed to control barley stripe rust this year.  Check barley fields for stripe rust, if severity reaches 5%, apply fungicide.  The fungicides that control wheat stripe rust also control barley stripe rust.

Table 1.  Stripe rust data of the 2017 WSU Spring Wheat Variety Trials at Lind, WA*

      Lind, WA  
      6/15/2017  
    2017 Feekes 10.5.3  
Name v_desc Plot # IT % Rating
14-FAC-2043 SWS 1 2 15 2
14-SW-1030 SWS 2 2 15 2
14-SW-1059 SWS 3 2 15 2
SY Saltese (SY 04PN3024-2) SWS 4 2 15 2
IDO1403S SWS 5 2 2 1
WB-1035CL+ SWSI 6 8 90 9
WB6121 SWS 7 2 10 2
WB6341 SWS 8 3 25 3
WB6430 SWS 9 3 20 3
Babe SWS 10 8 80 8
Diva SWS 11 2 15 2
JD SC 12 2 15 2
Louise SWS 13 3 15 2
Melba SC 14 2 10 2
Ryan (WA 8214) SWS 15 3 20 3
Seahawk SWS 16 2 2 1
Tekoa (WA 8189) SWS 17 2 10 2
WA 8236 CL+ SCI 18 2 5 1
WA 8265 CL+ SWSI 19 5 30 4
WA 8266 CL+ SWSI 20 5 30 4
AvS (Susceptible check)   21 8 100 9
WA 8277 SWS 22 2 10 2
WA 8278 SWS 23 5 30 4
Whit SWS 24 3 20 3
YS-603 SWS 25 2 10 2
14-FAC-2019   26 3 20 3
500-709 HRS 27 2 2 1
501-089 HRS 28 2 2 1
12SB0197 HRS 29 2 5 1
12SB0199 HRS 30 2 5 1
12SB0224 HRS 31 2 10 2
LCS Iron (11SB0096) HRS 32 2 15 2
LCS Luna (10SB0087-B) HRS 33 2 10 2
LCS Buck Pronto HRS 34 7 30 6
06PN3017-09 HRS 35 2,8 5,40 3
SY 06PN3015-08 HRS 36 2 2 1
SY Coho (04W40292R) HRS 37 2 5 1
SY Selway (04PN3001-2) HRS 38 2 10 2
SY Steelhead HRS 39 2 15 2
SY605 CL HRSI 40 8 40 7
AvS (Susceptible check)   41 8 100 9
IDO1603S HRS 42 2 5 1
WB9200 HRS 43 2 2 1
WB9229 HRS 44 2 2 1
WB9350 HRS 45 2 2 1
WB9411 HRS 46 2 10 2
WB9518 HRS 47 2 2 1
WB9662 HRS 48 2 5 1
WB9668 HRS 49 2 5 1
XA9861 HRS 50 2 2 1
Alum HRS 51 2 10 2
Chet HRS 52 2 10 2
Glee HRS 53 2 10 2
Hollis HRS 54 5 30 4
Kelse HRS 55 5 40 4
WA 8259 HRS 56 3 20 3
WA 8261 HRS 57 3 20 3
WA 8279 CL+ HRSI 58 3 20 3
WA 8280 CL+ HRSI 59 3 15 2
WA 8281 HRS 60 2 10 2
AvS (Susceptible check)   61 8 100 9
WA 8282 HRS 62 3 15 2
WQL17SSV16882-3 Durum 63 2/7 5/50 3
WQL18SALZ-3 Durum 64 2/5 5/40 3
SY Basalt HRS 65 2 5 1
WA 8263 HWS 66 3 30 3
WA 8283 HRS 67 2 5 1
WA 8284 HRS 68 3 15 2
WA 8285 HRS 69 2 2 1
Dayn HWS 70 2 5 1

* IT = infection type; % = severity based on infected leaf areas; and ratings are in a 1-9 scale with 1 for most resistant and 9 for most susceptible.

View the June 2017 Stripe Rust Update in PDF format.

Stripe Rust Update – April 2017

Dr. Xianming Chen, USDA-ARS Research Plant Pathologist in Pullman, and Dr. Mike Flowers, Oregon State University Extension Cereal Specialist, released disease updates (Dr. Chen’s update and Dr. Flower’s update) during the past week.

Not surprisingly, stripe rust has continued to develop on winter wheat across the region and is relatively easy to find.  Dr. Flowers reported finding stripe rust at variety testing locations near Dufur and Moro, OR, and in a commercial field near Moro. Dr. Chen reported finding actively sporulating stripe rust during the week of April 5 in over 80% of the approximately 70 fields checked in Adams, Benton, Columbia, Franklin, Garfield, Walla Walla, and Whitman Counties in WA, and Umatilla County in OR.

Stripe rust was most active near Walla Walla and Pendleton, where many fields have been sprayed with fungicide already. In other areas, rust ranged from 1 to 5% and is less severe than last year at this time due to lower temperatures. The Palouse in Whitman County is an exception, with stripe rust appearing about one month earlier than normal and similar to the severe epidemic years of 2011 and 2016.

Current weather forecasts continue to favor rust infection and spread, raising the potential for another severe stripe rust epidemic year. High-temperature adult-plant resistance (HTAP) has not kicked in yet and won’t become fully effective until nighttime/daytime temperatures are above 50°F/65°F.  Going forward, it will be important to continue scouting all winter wheat fields and consider using a fungicide with herbicide application if the variety is moderately susceptible or susceptible (rating 4 or greater in the Seed Buyers Guide) or active stripe rust is found on 2-5% of the plants in a field regardless of variety rating. Continue to monitor sprayed fields throughout the spring, especially near the end of fungicide effectiveness (3 to 4 weeks, depending on the fungicide).  For spring wheat, plant the most resistant variety available, preferably those rated 1 to 2.

Additional rust updates will be released as the growing season continues and conditions change. You can find additional information on stripe rust, including photos showing rust percentage, under Foliar Fungal Diseases in the Disease Resources section of the WSU Wheat and Small Grains website.


For questions or comments contact Tim Murray by email (tim.murray@wsu.edu), by phone (509) 335-7515, or Twitter (@WSUWheatDoc). For additional information contact Dr. Chen at xianming@wsu.edu or (509) 335-8086; or Mike Flowers at (541) 737-9940 or at Mike.Flowers@oregonstate.edu.

Eastern Oregon Disease Update March 2017

OW7Michael D. Flowers, Dept. of Crop and Soil Science
Oregon State University, 107 Crop Science Building, Corvallis, Oregon 97331-3002
T 541-737-9940 | F 541-737-1589 | Mike.Flowers@oregonstate.edu

March 16, 2017

To: Oregon Wheat Growers and Industry Reps
From: Mike Flowers, Larry Lutcher, Christina Hagerty and Chris Mundt; OSU
RE: Eastern Oregon Disease Update

Stripe Rust

Stripe rust was found on multiple varieties at the Lexington and Walla Walla variety testing locations. Early stripe rust infections appear to be spread throughout eastern Oregon and southeastern Washington. Growers are encouraged to scout their fields and tank mix a fungicide with their spring herbicide if stripe rust is present in their field and/or they are growing a highly susceptible variety (Mary, Brawl CL+, SY Ovation, ORCF-102 are examples).

Winter Injury and Snow Mold

Winter wheat fields throughout the region are showing symptoms of winter injury and/or snow mold. Winter injury symptoms are typically mild (burned leaf tips and yellow foliage) and plants will grow out of these symptoms as the weather warms. Snow mold symptoms (white or pink mycelial growth) are present in many fields but are spotty. Use a disc drill to fill in gaps, holes, or blank spots created by snow mold damage if affected areas continue to look questionable or fail to recover. Decisions to “sweeten-up” fields (or not) should be made quickly (in the next 4 to 10 days, depending on location).

To view this report in PDF format, click here.

 

Stripe Rust Forecast and Update- March 9, 2017

Stripe Rust Forecast and Update- March 9, 2017
Xianming Chen

Stripe rust will be likely severe in eastern Pacific Northwest

Based on the forecast models using the temperature data from November 2016 to February 2017, stripe rust will potentially cause yield loss of 32% on highly susceptible varieties. This number is much higher than the 6% forecasted in January based only on the November-December weather conditions. The number is an average of the prediction range from 9% to 41% using six models. The models do not take snow cover in to account. Although there were several periods of temperature below the point (5o F) under which the stripe rust fungus could not survive, most areas were covered with snow, which helped the pathogen survival. Based on field observations (below), stripe rust fungus has survived the cold winter. Considering these factors, our current prediction is in the severe range between 40% and 60% yield loss on highly susceptible varieties and the most “susceptible” commercially grown varieties, such as Xerpha and Eltan, will likely to have up to 30% yield loss.

Stripe rust starts growing in the Walla Walla area

Different from the last year, spring is coming slowly. Much of the northern part of Washington is still under snow and last night about 3 to 6 inches of snow fell in the Palouse region. Yesterday, we were checking wheat fields in Whitman, Lincoln, Adams, and Walla Walla counties in Washington. Stripe rust infection that occurred before the winter was recognizable (as dead spots) in many fields in Lincoln and Adams counties, indicating widespread and severe infection in last fall as reported in last November. Most fields in Lincoln County were under snow cover (Figure 1). The lower leaves of big plants in early planted fields in Lincoln and Adams counties were dead and some fields had severe winter injure (Figure 2). Most stripe rust fungus in leaves from infection of last fall should be dead, but some should have been survived. We were able to found stripe rust pustules (Figure 3) in a field just south of Odessa along Highway 21 in Lincoln County, showing pathogen survival. Please keep in mind that even one pustule of stripe rust in a field grown with a susceptible cultivar in the early spring can cause epidemic in the growing season if later on the weather conditions are favorable to the disease.

In Adams and Walla Walla counties, wheat has turned fresh green and started growing. There was no or very little winter injury. We found active stripe rust pustules (producing spores) in a commercial field (Figure 4) and also in our experimental field near Walla Walla. This early appearance of stripe rust is similar to the situation last year.

 

Figure 1
Figure 1: Snow cover in a winter wheat field between Harrington and Davenport in the northern part of Lincoln County, WA as observed on March 8, 2017.
Figure 2: A wheat field in Lincoln County, WA showing severe winter injure (March 8, 2017).
Figure 2: A wheat field in Lincoln County, WA showing severe winter injury (March 8, 2017).
Figure 3: Stripe rust pustules found in a winter wheat field near Odessa in Lincoln County, WA on March 8, 2017, indicating that the stripe rust fungus has survived the winter.
Figure 3: Stripe rust pustules found in a winter wheat field near Odessa in Lincoln County, WA on March 8, 2017, indicating that the stripe rust fungus has survived the winter.
Figure 4: Active stripe rust pustules found in a commercial wheat field near Walla Walla, WA on March 8, 2017.
Figure 4: Active stripe rust pustules found in a commercial wheat field near Walla Walla, WA on March 8, 2017.
Recommendations for the Pacific Northwest

As stripe rust has been found in Washington and is predicted to be severe, control of stripe rust is necessary. Some general recommendations for the eastern Pacific Northwest, similar to the recommendations made at this time last year, are the following:

  1. For winter wheat, check fields just before herbicide application. If a susceptible or moderately susceptible winter wheat variety (ratings 5 to 9 on the Buyers’ Guide) is planted, or you can found stripe rust in the field, consider using fungicide at the time of herbicide application
  2. For spring wheat, consider planting resistant varieties. Use the Seed Buyers Guide to choose varieties rated 1 to 4 for stripe rust and avoid those rated 5-9 if possible.
  3. As there have been plenty moisture, which will last long into the late spring and early summer, the weather conditions will be favorable for stripe rust development. Second application may be needed around the flag leaf stage, depending upon the first time of fungicide application, rust re-development in the field, variety with high-level of hightemperature adult-plant resistance or not, and weather conditions. General recommendation for using second application or not will be made late as the season progresses and rust develops.

Stripe rust in other states

This year, stripe rust has been reported so far in Texas, Louisiana, Mississippi, Arkansas, North Carolina, and Washington. Stripe rust was first reported in Texas on February 9, not much later than the last year in January. The rust seems to be not as widespread as this time of the last year. However, stripe rust was widespread in wheat nurseries in northern Louisiana by the late February. Last week and this week, we received stripe rust samples from Mississippi and Arkansas, respectively. On March 2, stripe rust was reported in North Carolina. Based on the past experience, if stripe rust is found in Texas and Louisiana before March, the disease will likely develop into severe and widespread epidemic throughout the Great Plains and further into the east regions except when drought conditions occur. Application of fungicides is recommended for fields grown with susceptible varieties. Fungicide timing needs to be based on local recommendations.

To view this report in PDF format, click here.

 

First Forecast of Stripe Rust for 2017 and 2016 Fungicide and Variety Yield Loss Tests

January 3, 2017
Xianming Chen

A. First forecast for the eastern PNW in 2017

The current forecast is that highly susceptible winter wheat varieties would have 6% yield loss, in the low epidemic level range (0-20% yield loss). Based on this forecast, currently grown varieties would not have significant yield loss and early fungicide application at the time of herbicide application time for winter wheat would not be necessary. This forecast is based on only the temperatures of November and December 2016 and does not include snow cover into the models. If snow cover has been and will be about 3 inches or higher during the periods of temperatures below 14 o F, the stripe rust fungus in wheat leaves will likely survive the winter. If so, the stripe rust level will be higher than the forecasted value. Therefore, more accurate forecast will depend upon whether or not and to what degree the pathogen will survive throughout the winter.

In early March, we will make another forecast based on the weather conditions of the entire winter season, which is generally more accurate than the early forecast. We will also check in early March if rust survives the winter. On November 8, 2016, we were checking winter wheat fields in Whitman, Lincoln, Adams, Grant, Douglas, and Benton counties in eastern Washington. High rust incidences were found in many fields. After that, there were several reports of stripe rust in eastern Washington, northeastern Oregon, and southern Idaho. The stripe rust infection in the fall was the most severe and widespread in the eastern Pacific Northwest (PNW). The cold weather conditions (below 14o F) should have killed some rust, but snow cover could protect the rust fungus in wheat leaves.

B. Yield losses caused by stripe rust and increases by fungicide application on wheat varieties in 2016

Stripe rust and yield differences in non-sprayed and fungicide-sprayed plots of winter wheat varieties are shown in Table 1 and of spring wheat varieties in Table 2. Of the 24 winter wheat varieties tested including susceptible check ‘PS 279’, 13 varieties (PS 279, Xerpha, Eltan, ORCF-103, ORCF-102, Whetstone, Keldin, ARS-Crescent, Westbred 528, Puma, ARS-Crystal, Jasper, and WB 523) had significant differences in stripe rust severity (presented as rAUDPC) between the nonsprayed and sprayed treatments; 6 varieties (PS 279, Xerpha, Eltan, ORCF-103, ORCF-102, and ARS-Crystal) had significant differences in grain test weight; and 6 varieties (PS 279, Xerpha, Eltan, ORCF-103, ORCF-102, and WB-Arrowhead) had significant differences in yield (Table 1). Stripe rust caused 71% yield loss on the susceptible check (PS 279) and from 0 to 32% yield losses at an average of 8% on commercially grown varieties. Fungicide application increased yield by 0 to 47% at an average of 10% on commercially grown varieties. Under the extreme severe level of stripe rust epidemic, five (Xerpha, Eltan, ORCF-103, ORCF-102, and WB-Arrowhead) of the tested commercially grown winter varieties needed fungicide application as they had significant yield losses and received fungicide application ratings 2 to 4. All other tested commercial varieties did not have significant yield losses and received fungicide application rating of 1 and therefore, did not need fungicide application. Similarly, of the 16 spring wheat varieties tested including susceptible check ‘AvS’, all had significant differences in stripe rust severity (presented as rAUDPC), except Expresso and JD; only

Similarly, of the 16 spring wheat varieties tested including susceptible check ‘AvS’, all had significant differences in stripe rust severity (presented as rAUDPC), except Expresso and JD; only AvS had significant difference in grain test weight; and nine varieties had significant differences in grain yield (Table 2). Stripe rust caused 54% yield loss on the susceptible check and from 0 to 43% yield losses at an average of 20% on commercial varieties. Fungicide application increased grain yields by 0 to 74% on commercial varieties at an average of 29%. The nine varieties that had significantly different yield losses received fungicide application ratings 2 or 3, while the remaining seven varieties that did not have significantly different yields between sprayed and non-sprayed treatments received rating 1 and therefore, did not need fungicide application under the severe epidemic. The data can be used to select stripe rust resistant varieties to plant and to determine if

The data can be used to select stripe rust resistant varieties to plant and to determine if fungicide application is needed for a variety based on the relative yield loss and potential epidemic level. The current forecasted epidemic level (6% yield loss on susceptible varieties) for 2017 is similar to the stripe rust situation in 2014. Therefore, fungicide application will be generally unnecessary, unless future forecasts and situations are changed.

C. Fungicide tests in 2016

Various foliar fungicide treatments were tested for their effectiveness on winter wheat and spring wheat grown in fields near Pullman, Washington. Severe stripe rust epidemic occurred naturally.

In winter wheat field, stripe rust started developing in late April when plants were at the early jointing stage (Feekes 4) and reached 80% and 100% severity at the boot (Feekes 10) and flowering (Feekes 10.5) stages, respectively in the non-treated check plots (Table 3). All fungicide treatments of the first application significantly reduced rust severity compared to the non-treated check and the treatments without the first application at the boot stage. All treatments with only the first application did not significantly reduce rust severity compared to the non-treated check at the flowering stage, except one treatment. Significant differences in test weight were observed among the fungicide treatments. Treatments of only the first application had significantly low test weight compared to those with the later applications. Most treatments significantly increased gain yield compared with the non-treated check, and the significant increases ranged from 19 bushes (164%) to 91 bushes (797%).

In the spring wheat field, stripe rust started developing in late May when plants were at the tillering stage (Feekes 2-3) and reached 90% at the flowering (Feekes 10.5) and 100% severity at the milk stages in the nonfungicide check plots (Table 4). All fungicide treatments with the first application significantly reduced rust severity compared to the non-treated check and the treatments without the first application at the boot stage, and all treatments with only the first application did not significantly reduce rust severity compared to the nontreated check at the milk (data not presented) and soft dough stages. Significant differences in grain test weight were observed among the fungicide treatments. The test weights from treatments of only the first application were similar to that of non-treated check; and those of treatments with the late application were significantly higher than that of the non-treated check, except few treatments. Most fungicide treatments significantly increased yield compared with the non-treated check. The significant increases of grain yield ranged from 8 bushes (65%) to 56 bushes (449%) depending upon fungicide treatments.

To view this report in PDF format, including the tables, click here

First Forecast of Stripe Rust for 2017 and 2016 Fungicide and Variety Yield Loss Tests

January 3, 2017
Xianming Chen

A. First forecast for the eastern PNW in 2017

The current forecast is that highly susceptible winter wheat varieties would have 6% yield loss, in the low epidemic level range (0-20% yield loss). Based on this forecast, currently grown varieties would not have significant yield loss and early fungicide application at the time of herbicide application time for winter wheat would not be necessary. This forecast is based on only the temperatures of November and December, 2016 and does not include snow cover into the models. If snow cover has been and will be about 3 inches or higher during the periods of temperatures below 14 o F, the stripe rust fungus in wheat leaves will likely survive the winter. If so, the stripe rust level will be higher than the forecasted value. Therefore, more accurate forecast will depend upon whether or not and to what degree the pathogen will survive throughout the winter.

In early March, we will make another forecast based on the weather conditions of the entire winter season, which is generally more accurate than the early forecast. We will also check in early March if rust survives the winter. On November 8, 2016, we were checking winter wheat fields in Whitman, Lincoln, Adams, Grant, Douglas, and Benton counties in eastern Washington. High rust incidences were found in many fields. After that, there were several reports of stripe rust in eastern Washington, northeastern Oregon, and southern Idaho. The stripe rust infection in the fall was the most severe and widespread in the eastern Pacific Northwest (PNW). The cold weather conditions (below 14o F) should have killed some rust, but snow cover could protect the rust fungus in wheat leaves.

B. Yield losses caused by stripe rust and increases by fungicide application on wheat varieties in 2016

Stripe rust and yield differences in non-sprayed and fungicide-sprayed plots of winter wheat varieties are shown in Table 1 and of spring wheat varieties in Table 2. Of the 24 winter wheat varieties tested including susceptible check ‘PS 279’, 13 varieties (PS 279, Xerpha, Eltan, ORCF-103, ORCF-102, Whetstone, Keldin, ARS-Crescent, Westbred 528, Puma, ARS-Crystal, Jasper, and WB 523) had significant differences in stripe rust severity (presented as rAUDPC) between the nonsprayed and sprayed treatments; 6 varieties (PS 279, Xerpha, Eltan, ORCF-103, ORCF-102, and ARS-Crystal) had significant differences in grain test weight; and 6 varieties (PS 279, Xerpha, Eltan, ORCF-103, ORCF-102, and WB-Arrowhead) had significant differences in yield (Table 1). Stripe rust caused 71% yield loss on the susceptible check (PS 279) and from 0 to 32% yield losses at an average of 8% on commercially grown varieties. Fungicide application increased yield by 0 to 47% at an average of 10% on commercially grown varieties. Under the extreme severe level of stripe rust epidemic, five (Xerpha, Eltan, ORCF-103, ORCF-102, and WB-Arrowhead) of the tested commercially grown winter varieties needed fungicide application as they had significant yield losses and received fungicide application ratings 2 to 4. All other tested commercial varieties did not have significant yield losses and received fungicide application rating of 1 and therefore, did not need fungicide application. Similarly, of the 16 spring wheat varieties tested including susceptible check ‘AvS’, all had significant differences in stripe rust severity (presented as rAUDPC), except Expresso and JD; only

Similarly, of the 16 spring wheat varieties tested including susceptible check ‘AvS’, all had significant differences in stripe rust severity (presented as rAUDPC), except Expresso and JD; only AvS had significant difference in grain test weight; and nine varieties had significant differences in grain yield (Table 2). Stripe rust caused 54% yield loss on the susceptible check and from 0 to 43% yield losses at an average of 20% on commercial varieties. Fungicide application increased grain yields by 0 to 74% on commercial varieties at an average of 29%. The nine varieties that had significantly different yield losses received fungicide application ratings 2 or 3, while the remaining seven varieties that did not have significantly different yields between sprayed and non-sprayed treatments received rating 1 and therefore, did not need fungicide application under the severe epidemic. The data can be used to select stripe rust resistant varieties to plant and to determine if

The data can be used to select stripe rust resistant varieties to plant and to determine if fungicide application is needed for a variety based on the relative yield loss and potential epidemic level. The current forecasted epidemic level (6% yield loss on susceptible varieties) for 2017 is similar to the stripe rust situation in 2014. Therefore, fungicide application will be generally unnecessary, unless future forecasts and situations are changed.

C. Fungicide tests in 2016

Various foliar fungicide treatments were tested for their effectiveness on winter wheat and spring wheat grown in fields near Pullman, Washington. Severe stripe rust epidemic occurred naturally.

In winter wheat field, stripe rust started developing in late April when plants were at the early jointing stage (Feekes 4) and reached 80% and 100% severity at the boot (Feekes 10) and flowering (Feekes 10.5) stages, respectively in the non-treated check plots (Table 3). All fungicide treatments of the first application significantly reduced rust severity compared to the non-treated check and the treatments without the first application at the boot stage. All treatments with only the first application did not significantly reduce rust severity compared to the non-treated check at the flowering stage, except one treatment. Significant differences in test weight were observed among the fungicide treatments. Treatments of only the first application had significantly low test weight compared to those with the later applications. Most treatments significantly increased gain yield compared with the non-treated check, and the significant increases ranged from 19 bushes (164%) to 91 bushes (797%).

In the spring wheat field, stripe rust started developing in late May when plants were at the tillering stage (Feekes 2-3) and reached 90% at the flowering (Feekes 10.5) and 100% severity at the milk stages in the nonfungicide check plots (Table 4). All fungicide treatments with the first application significantly reduced rust severity compared to the non-treated check and the treatments without the first application at the boot stage, and all treatments with only the first application did not significantly reduce rust severity compared to the nontreated check at the milk (data not presented) and soft dough stages. Significant differences in grain test weight were observed among the fungicide treatments. The test weights from treatments of only the first application were similar to that of non-treated check; and those of treatments with the late application were significantly higher than that of the non-treated check, except few treatments. Most fungicide treatments significantly increased yield compared with the non-treated check. The significant increases of grain yield ranged from 8 bushes (65%) to 56 bushes (449%) depending upon fungicide treatments.

To view this report in PDF format, including the tables, click here

 

 

Stripe Rust Forecast and Update- March 9, 2017

Stripe Rust Forecast and Update- March 9, 2017
Xianming Chen

Stripe rust will  be likely severe in eastern Pacific Northwest

Based on the forecast models using the temperature data from November 2016 to February 2017, stripe rust will potentially cause yield loss of 32% on highly susceptible varieties. This number is much higher than the 6% forecasted in January based only on the November-December weather conditions. The number is an average of the prediction range from 9% to 41% using six models. The models do not take snow cover in to account. Although there were several periods of temperature below the point (5o F) under which the stripe rust fungus could not survive, most areas were covered with snow, which helped the pathogen survival. Based on field observations (below), stripe rust fungus has survived the cold winter. Considering these factors, our current prediction is in the severe range between 40% and 60% yield loss on highly susceptible varieties and the most “susceptible” commercially grown varieties, such as Xerpha and Eltan, will likely to have up to 30% yield loss.

Stripe rust starts growing in the Walla Walla area

Different from the last year, spring is coming slowly. Much of the northern part of Washington is still under snow and last night about 3 to 6 inches of snow fell in the Palouse region. Yesterday, we were checking wheat fields in Whitman, Lincoln, Adams, and Walla Walla counties in Washington. Stripe rust infection that occurred before the winter was recognizable (as dead spots) in many fields in Lincoln and Adams counties, indicating widespread and severe infection in last fall as reported in last November. Most fields in Lincoln County were under snow cover (Figure 1). The lower leaves of big plants in early planted fields in Lincoln and Adams counties were dead and some fields had severe winter injure (Figure 2). Most stripe rust fungus in leaves from infection of last fall should be dead, but some should have been survived. We were able to found stripe rust pustules (Figure 3) in a field just south of Odessa along Highway 21 in Lincoln County, showing pathogen survival. Please keep in mind that even one pustule of stripe rust in a field grown with a susceptible cultivar in the early spring can cause epidemic in the growing season if later on the weather conditions are favorable to the disease.

In Adams and Walla Walla counties, wheat has turned fresh green and started growing. There were no or very little winter injure. We found active stripe rust pustules (producing spores) in a commercial field (Figure 4) and also in our experimental field near Walla Walla. This early appearance of stripe rust is similar to the situation last year.

Figure 1. Snow cover in a winter wheat field between Harrington and Davenport in the northern part of Lincoln County, WA as observed on March 8, 2017.
Figure 1: Snow cover in a winter wheat field between Harrington and Davenport in the northern part of
Lincoln County, WA as observed on March 8, 2017.
Figure 2. A wheat field in Lincoln County, WA showing severe winter injure (March 8, 2017).
Figure 2: A wheat field in Lincoln County, WA showing severe winter injure (March 8, 2017).

 

 

 

 

 

 

 

 

 

 

Figure 3. Stripe rust pustules found in a winter wheat field near Odessa in Lincoln County, WA on March 8, 2017, indicating that the stripe rust fungus has survived the winter.
Figure 3: Stripe rust pustules found in a winter wheat field near Odessa in Lincoln County, WA on March 8, 2017, indicating that the stripe rust fungus has survived the winter.
Figure 4. Active stripe rust pustules found in a commercial wheat field near Walla Walla, WA on March 8, 2017.
Figure 4: Active stripe rust pustules found in a commercial wheat field near Walla Walla, WA on March 8, 2017.

 

 

 

 

 

 

 

 

 

 

Recommendations for the Pacific Northwest

As stripe rust has been found in Washington and is predicted to be severe, control of stripe rust is necessary. Some general recommendations for the eastern Pacific Northwest, similar to the recommendations made at this time last year, are the following:

  1. For winter wheat, check fields just before herbicide application. If a susceptible or moderately susceptible winter wheat variety (ratings 5 to 9 on the Buyers’ Guide) is planted, or you can found stripe rust in the field, consider using fungicide at the time of herbicide application
  2. For spring wheat, consider planting resistant varieties. Use the Seed Buyers Guide to choose varieties rated 1 to 4 for stripe rust and avoid those rated 5-9 if possible.
  3. As there have been plenty moisture, which will last long into the late spring and early summer, the weather conditions will be favorable for stripe rust development. Second application may be needed around the flag leaf stage, depending upon the first time of fungicide application, rust re-development in the field, variety with high-level of hightemperature adult-plant resistance or not, and weather conditions. General recommendation for using second application or not will be made late as the season progresses and rust develops.

Stripe rust in other states

This year, stripe rust has been reported so far in Texas, Louisiana, Mississippi, Arkansas, North Carolina, and Washington. Stripe rust was first reported in Texas on February 9, not much later than the last year in January. The rust seems to be not as widespread as this time of the last year. However, stripe rust was widespread in wheat nurseries in northern Louisiana by the late February. Last week and this week, we received stripe rust samples from Mississippi and Arkansas, respectively. On March 2, stripe rust was reported in North Carolina. Based on the past experience, if stripe rust is found in Texas and Louisiana before March, the disease will likely develop into severe and widespread epidemic throughout the Great Plains and further into the east regions except when drought conditions occur. Application of fungicides is recommended for fields grown with susceptible varieties. Fungicide timing needs to be based on local recommendations.

To view this report in PDF format, click here.

 

Eastern Oregon Disease Update March 2017

OW7Michael D. Flowers, Dept. of Crop and Soil Science
Oregon State University, 107 Crop Science Building, Corvallis, Oregon 97331-3002
T 541-737-9940 | F 541-737-1589 | Mike.Flowers@oregonstate.edu

March 16, 2017

To: Oregon Wheat Growers and Industry Reps
From: Mike Flowers, Larry Lutcher, Christina Hagerty and Chris Mundt; OSU
RE: Eastern Oregon Disease Update

Stripe Rust

Stripe rust was found on multiple varieties at the Lexington and Walla Walla variety testing locations. Early stripe rust infections appear to be spread throughout eastern Oregon and southeastern Washington. Growers are encouraged to scout their fields and tank mix a fungicide with their spring herbicide if stripe rust is present in their field and/or they are growing a highly susceptible variety (Mary, Brawl CL+, SY Ovation, ORCF-102 are examples).

Winter Injury and Snow Mold

Winter wheat fields throughout the region are showing symptoms of winter injury and/or snow mold. Winter injury symptoms are typically mild (burned leaf tips and yellow foliage) and plants will grow out of these symptoms as the weather warms. Snow mold symptoms (white or pink mycelial growth) are present in many fields but are spotty. Use a disc drill to fill in gaps, holes, or blank spots created by snow mold damage if affected areas continue to look questionable or fail to recover. Decisions to “sweeten-up” fields (or not) should be made quickly (in the next 4 to 10 days, depending on location).

To view this report in PDF format, click here.

 

Washington State University