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Wheat & Small Grains Blythe Howell

Podcast Dissects Falling Number Phenomenon

Learn more about the discount that cost Eastern Washington wheat farmers at least $30 million and perhaps as much as $140 million in 2016. Episodes 12 & 13 of the Washington Grain Commission-sponsored podcast, Wheat All About It! both address falling numbers. The two podcasts are from a falling numbers panel held during Spokane Ag… » More ...

Pink Snow Mold Destruction Discovered in Area Wheat Fields

Furrows of bleached-looking leaves of winter wheat damaged by pink snow mold in a Prescott, Wash., field.
By Linda Weiford, WSU News

Damage caused by snow mold in some eastern Washington wheat fields has surprised a Washington State University plant expert who has studied the fungus for nearly four decades.

Melting snow is exposing patches of injured wheat in parts of the state where destruction by snow mold is rarely seen, said WSU plant pathologist Tim Murray. He recently met with 20 growers in the town of Prescott, Wash., to address their concerns about the mold’s impact on winter wheat.

“Growers in this area have never seen this mold until now,” he said. “Its presence may have surprised me, but it really surprised them.”

After examining a half-dozen fields in southcentral and southeastern Washington, Murray identified winter wheat damage ranging from nonthreatening lesions on leaves to underground crown decay that kills the crop.

“I was surprised to see how prevalent the damage was in some of the fields,” he said. “We’ll definitely be seeing some economic damage as a result.” He stressed that the extent can’t be tallied until soils are warm enough to reveal which plants could withstand the damage and which could not.

Pink Fungus Among Us
A cold-loving organism that thrives under long periods of snow cover, so-called pink snow mold attacks perennial plants and overwintering crops. It’s more commonly seen in the higher elevations of northcentral Washington where snow blankets the ground for 100 days or more.

But this winter’s pervasive snowy weather fueled the mold’s growth in lower elevations as well, said Murray, including Walla Walla, Whitman and Columbia counties. Caused by the fungus Microdochium nivale, the pink-tinged mold is showing up in fields of winter wheat and even lawns of grass, he said.

“Snow protects winter wheat and other dormant plants from cold temperatures, which is a good thing,” he explained. “But the snow cover becomes a problem when it stays on the ground for too long, which is just what happened.”

In areas where the fungal disease is evident, snow had covered the ground 60-70 days. Although longer than most years, “it’s still not long enough to cause the kind of damage I’ve been seeing. It typically takes at least 100 days,” said Murray.

Why, then, is the fungus among us? Abnormally warm temperatures in November kept the ground from freezing before the first hard snow arrived, creating a more hospitable environment for Microdochium nivale to grow, he explained. That, coupled with a longer-than-usual period of snow cover, gave it just what it needed to thrive.

“The fungus is out there. As we’ve seen, when the weather allows it to take advantage of the situation, it does,” he said.

Growers Advised to Wait
Murray has spent 40 years helping to develop high-quality wheat varieties that mount a defense reaction against snow mold and other diseases that plague the crop in cold climates. Microdochium nivale is one of three fungi that cause snow mold in Washington.

Murray is advising growers to let a few weeks of warmer weather pass in order to assess the full impact of damage in their fields. At that point, they can decide whether reseeding will be necessary.


For questions or comments, contact Tim Murray by phone at 509-335-7515, by email at tim.murray@wsu.edu, or on Twitter @WSUWheatDoc or contact Linda Weiford at 509-335-7209 or linda.weiford@wsu.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

White Paper: Strategies to Reduce Economic Losses Due to Low Falling Number in Wheat

The White Paper was developed after the recent Falling Numbers Summit in Spokane, WA on Feb 16, 2017. That event was unique because it brought together a wide group of members of the grain industry, including federal and state grain inspectors, elevator operators, grain millers and bakers, the research community, grain commissions and grower groups, exporters and state extension services and representatives from private sector agronomy and plant breeding companies.

Since 2011, low falling numbers have cost western farmers millions of dollars. Economic losses to the grain industry in 2016 alone exceeded $30 million at harvest and will likely approach $140 million in total. The two causes of low FNs in wheat grain are: 1) pre-harvest sprouting or germination on the mother plant due to rain before harvest, and 2) late maturity alpha-amylase (LMA) due to heat or cold shock during grain development.

At the meeting, the members of the grain community shared current knowledge, determined where more knowledge is needed, developed priorities for action and assigned leaders to each priority action item. The focus of the meeting was on short (3-6 month) and mid-term (6 months to 2 years) strategies. The white paper identifies the strategies and outcomes from that meeting. The immediate goals are to improve the Falling number test by increasing the standardization of the testing protocol and to analyze existing data to detect patterns in the response of wheat varieties.  All results will be posted on the Small Grains Grain Quality Resources page.

A follow-up meeting for researchers will occur at the Western Wheat Workers Conference in Corvallis, May 31-June 1 and a follow-up meeting for the industry will occur at the Tri-State Grain Growers Convention in Spokane in November 2017.


For questions or comments, contact Kimberly Campbell at (208) 310-9876 or at kim.garland-campbell@ars.usda.gov.

Stripe Rust Update – March 2017

Dr. Chen, USDA-ARS Research Plant Pathologist in Pullman, and the Oregon State University Variety Testing and Plant Pathology Team (Mike Flowers, Larry Lutcher, Christina Hagerty and Chris Mundt) each released disease updates (Dr. Chen’s report and the Plant Pathology’s report) during the past week.

Using six different models based on air temperature, Dr. Chen is predicting this year’s stripe rust epidemic will be more severe than his first prediction in January.  Although air temperature during several periods in December and January was below the 5°F threshold for survival of the stripe rust fungus in plants, most of the wheat-growing area in eastern Washington had a blanket of snow cover that protected both winter wheat plants and the fungus, allowing both to survive. Consequently, Dr. Chen is now predicting an epidemic with potential yield loss of 32% on highly susceptible varieties, compared to 6% in his January forecast. Dr. Chen also reported finding actively sporulating stripe rust pustules during the week of March 6 in Walla Walla County where the wheat has greened-up and started growing. Fields farther to the north in Adams and Lincoln Counties were either still under snow or, where snow was gone, had dead spots where rust infection was severe last fall, or fall-infected leaves were dead. It is possible that the stripe rust fungus is still alive in these plants and may begin to sporulate once the plants begin growing again. These observations were confirmed in the OSU report, and stripe rust was observed on several varieties at two variety testing locations (Lexington, OR and Walla Walla, WA) and appears to be widespread in eastern Oregon and southeastern Washington.

Going forward, it will be important to scout all winter wheat fields and consider using a fungicide with herbicide application if the variety is moderately susceptible or susceptible (rating of 5 to 9) or active stripe rust is found on 2-5% of the plants in a field. Continue to monitor fields throughout the spring, especially as the end of fungicide effectiveness nears (3 to 5 weeks, depending on the fungicide).  For spring wheat, plant the most resistant variety available, preferably those rated 1 to 4.


For questions or comments, contact Dr. Chen at xianming@wsu.edu or (509) 335-8086 or Tim Murray by email (tim.murray@wsu.edu), by phone (509-335-7515), or Twitter (@WSUWheatDoc).

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.

 

Washington State University