Stripe Rust Levels Lower in 2012

Stripe Rust Update: Stripe rust has developed slower this year than in 2011, with levels lower than 2011 or 2010. There have been a few reports of it in Umatilla and Walla Walla Counties, but it is not widespread and is about normal for the stage of development for wheat in the area. In eastern Washington and northeastern Oregon, stripe rust has started showing up, but still remained hard to find.  Dr. Xianming Chen, USDA ARS, Pullman, was checking fields in western Whitman, Columbia, Walla Wall, Franklin, and Adams counties in eastern Washington and around Pendleton and Hermiston (Umatilla Co.) in eastern Oregon this week.  He notes that winter wheat ranged from early jointing (Feeks 4) to early boot (Feeks 10). He only found stripe rust on lower leaves of one volunteer plant in our stripe rust nursery (planted in late September) near Walla Walla.  No stripe rust was found on any entries and spreader rows of a highly susceptible genotype.  No stripe rust was found in any commercial fields checked including those around Prescott and in the Horse Heaven Hills. 

The following graph, provided by Dr. Mike Flowers, OSU, shows the generation time which is  the time from infection to visible stripe rust in Hermiston area.  As the temperatures increase, the generation time decreases.  As you can tell from the graphs, the generation time for stripe rust is currently running around 15-20 days, depending on location.

Figure: Stripe Rust Generation, April 24, 2012

Please check your fields before spraying.  Our general recommendation is no spray without seeing rust and spray when rust reaches to 1 to 5% prevalence (percent of plants with rust pustules).   Based on current low stripe rust pressure, susceptible and moderately susceptible varieties may just need only one application at the flag-heading stage; and moderately resistant varieties may or not need to spray fungicides   (depending upon weather conditions in May) according to Dr. Chen.  The long-term weather forecast for May to July just issued today predicted a slightly cooler than average (just 1^oF difference) for the PNW. 

Stripe Rust Forecast and Update by Dr. Chen

Stripe Rust Forecast and Update

March 5, 2012

Xianming Chen

Field survey

On March 1, I was checking wheat fields in Whitman, Columbia, Walla Walla, Benton, and Franklin counties in Washington, mostly south of Highway 26.   Plants ranged from two-leaf stage to early jointing (Feekes 1-5), depending upon planting time and region.   In most wheat fields, plants were still in winter dormancy and did not grown much compared to growth stages in early November, but became uniform especially in late planted fields.  No rust was found in any of the checked fields.  There was no obvious winter injury or other diseases.

Prediction and management suggestion

Using a series of forecast models based on various weather parameters from December to February (Sharma-Poudyal and Chen, Phytopathology 101:544-554, 2011), the new prediction  of potential yield loss caused by stripe rust on susceptible winter wheat varieties is 35±5%, dropping from the 47% forecasted based on only the December  weather.  This level is within a moderate epidemic category.  The prediction is based on historical yield loss and weather data of the Palouse region and is applicable for most wheat growing regions in the Pacific Northwest, except western Washington, western Oregon, and southern Idaho as these regions have very different weather patterns.  

Stripe Rust in 2011.

With the moderate level of damage potential, susceptible and moderately susceptible varieties may need to be sprayed with fungicide (possibly just once) and resistant and moderately resistant varieties may not need spray. 

Please keep in mind that the current prediction can be realized only if the weather conditions from now throughout the remaining growing season are normal (past long-term averages).  If May and June are unusually cool and wet, just like in 2010, stripe rust would be severer than the current prediction.  On the other hand, if the weather conditions from April to June are drier and from May to June hotter than normal, stripe rust would be lower than the current prediction.   

Nevertheless, based on the current prediction and field observations, stripe rust will definitely not be as severe as 2011 (but still have possibilities to be as severe as in 2010), applications of fungicides may not be necessary until you see stripe rust (5-10% incidence) in your fields.   

Checking fields should be started from later March in eastern Oregon and southern-central Washington (Horse Heaven Hills, Connell areas, and Walla Walla) and from middle April in areas further north and east in Washington and Idaho.  In western Washington, stripe rust should be visible as always in this time of the year.  Application of fungicides together with herbicides in fields grown with susceptible and moderately susceptible varieties should be a standard procedure for maximizing profit every year in western Washington.

Current stripe rust situations in other states

Stripe rust was first reported in Arkansas on January 27, in Mississippi on January 30, in California in the last week of February, and in Texas on March 1.  Stripe rust has been developing and spreading quickly in Arkansas and Mississippi.   The recent storms and tornadoes would have spread stripe rust spores to infect wheat fields in states further north and east. 

First Forecast of Stripe Rust for the Pacific Northwest in 2012

January 2, 2012, by Dr. Xianming Chen, USDA ARS, Pullman, Washington

Based on the 2011 December temperatures, stripe rust yield loss on highly susceptible winter wheat cultivars is predicted to be 47%.  The value is calculated using the formula Y (yield loss) = 84.3 – 0.323X, where X is the absolute value of the accumulated value of negative degree days based on daily maximum temperatures.The negative degree day value for a day equals the maximum temperature (^oC) subtracted by 7 (^oC).   

This is the first of a series of models we use to predict stripe rust damage on susceptible cultivars for the major wheat growing region in the Pacific Northwest.  For more information about this formula and other formulas, you may refer to our recent publication (Sharma-Poudyal, D., and Chen, X. M. 2011.  Models for predicting potential yield loss of wheat caused by stripe rust in the US Pacific Northwest. Phytopathology 101:544-554).

If we classify stripe rust yield losses into four categories, low (equal to or less than 20%), moderate (more than 20% but equal to or less than 40%), severe (more than 40% but equal to or less than 60%), and extremely severe (more than 60%), the predicted level of 47% for 2012 indicates a severe level, higher than normal (35%).  For comparison, the 2010 stripe rust epidemic caused 60% yield loss and the 2011 caused more than 90% on highly susceptible winter wheat cultivars.

  

Please keep in mind that this prediction is based on the winter weather so far.  If the weather conditions from now to June are close to normal, the prediction will be very close to the real disease situation.  The other models using the weather data from the entire November to February give better predictions.  Our next forecast will be in early March.

OSU Cereal Seminar & Sustainable Ag Forum

Stripe rust, wireworm control, new drill prototype, microbiology and nitrogen fertilizer management are just a few of the wide array of topics to be covered at the Columbia Basin Cereal Seminar & Sustainable Ag Forum on December 14 present in partnership by OSU Extension and Umatilla County Soil and Water Conservation District. 

The open session will begin with a conservation research update in low rainfall zones by Bill Schillinger of Washington State University in Lind, Washington. Dr. Schillinger’s work has focused on reduced and no-till dryland cropping systems for cereal crops in the Pacific Northwest. He will be talking about the development and testing of new deep-furrow drill prototypes, his successes with winter triticale, and no-till summer fallow. 

In addition, McGregor Company will be bringing a section of their new deep-furrow drill to the seminar and it will be on display at the BMCC Ag Complex where the seminar lunch will be served. In the afternoon breakout session on Precision Ag, Paul Buchholtz of McGregor Company will present additional information about the drill and how their testing and development program is going for it use in the PNW.

Other presenters during the morning session will include “Stripe Rust Impacts on Wheat,” Chris Mundt, OSU pathologist, “Pesticide Drift Prevention Strategies,” Cory Cooley, ODA pesticide investigator, “Wireworm Biology and Control in Wheat,” Aaron Esser, WSU Extension agronomist, “Microbiology: some tricks up our sleeves,” Kate Reardon, USDA ARS, “Wheat Insect Pests,” Silvia Rondon, OSU Extension entomologist, and an Update from Oregon Wheat Commission and Oregon Wheat Growers League.

The afternoon will have two tracks of presentations: Track One- Precision Ag will cover deep furrow, high residue drill update, early seeded canola, managing nitrogen using optical sensors, and a panel of growers talking about their on-farm use of variable rate fertilizers. Presenting growers include Herb March of Milton Freewater, Berk Davis of Adams, and Bill Jepsen of Heppner, Oregon.

Track Two for the afternoon will be a pesticide CORE training session covering “Principles of IPM,” “Drift: What is it, when does it happen, and how can we prevent it,” “Sprayer Calibration,” and “Testing Your Knowledge: Pesticide Jeopardy.” 

For a detailed agenda: 

Columbia Basin Cereal Seminar & Sustainable Ag Forum 

Pesticide recertification credits and Certified Crop Advisor credits are available in the morning and afternoon session. See full agenda for details. There is a $10 registration fee for the seminar which includes lunch. To preregister go online to: www.umatillacountyswcd.com or call Shevon at OSU Extension office (541) 278-5403.

Christmas wish lists

With Christmas fast approaching, perhaps you are working on a wish list of new iron to add to your packages under the Christmas tree? With that in mind, and having read Craig Reeder's recent column in the Oregon Wheat Magazine, I thought I should share with you a revised publication from the University of Idaho.

When I receive calls about the cost of equipment and local leasing rates for different farming practices this is the only resource that I have to provide to growers that provides an analysis of farm machinery costs. With ongoing economic pressures farmers need to continue paying attention to managing their machinery resources, now more than ever. 

The longstanding trend of substituting financial capital for labor by adding more productive and higher capacity machinery has resulted in large amounts of capital being used annually to acquire and operate farm machinery. On today’s commercial farm, substantial components of both capital investment and annual production costs are machinery related. As a result, farmers must not overlook effective strategies to manage their machinery resources.

Effectively managing machinery resources requires having adequate answers on a continuing basis to the following questions:

• What size of machinery is most economical? 
• How much machinery is needed for a given acreage and/or crop mix?
•  Should machinery be leased, rented, custom-hired, or purchased?
• Should new or used machinery be purchased?
• How long should machinery be kept before it is replaced?

A farmer needs to know machinery costs to deal effectively with these management questions. Yet, many farmers do not keep adequate records of machinery costs.The link below will take you to the full publication and tables for the publication which can help you answer some of the questions listed above:

PNW 346, Costs of Owning and Operating Farm Machinery in the Pacific Northwest, 2011

http://www.cals.uidaho.edu/edComm/pdf/PNW/PNW0346/PNW0346.html

Happy Holidays, and best wishes in the coming year.

Stripe Rust Fall Infection Levels

The following observations of stripe rust fall infection levels were made by Dr. Xianming Chen, USDA ARS, Pullman on November 3, 2011 in eastern Washington:

On November 3, we were checking stripe rust infection in winter wheat fields along Highway 23, Platter Rd, Doerschlag Rd, Lake Rd, Stromberger Rd, and Danekas Rd in Whitman, Adam, and Lincoln counties and the Horse Heaven Hills region in Benton County in Washington.  Wheat ranged from non-emerged to early jointing (Feekes 5).  We only check fields with big plants (Feekes 3-5) as big plants were more likely to be infected. 

We found stripe rust pustules in 6 fields out of a total of 15-20 fields that were carefully checked: two fields west of St. John and east of Sprague along HW 23 in Whitman County (Fig. 1); one field along Stromberger Rd in Lincoln County near the Adam County border; one field along Doerschlag Rd; one field along Danekas Rd about five miles east of Ritzville in Adams County and one field in Horse Heaven Hills in Benton County (Fig. 2).  We were able to found only 1 or 2 leaves with rust pustules in each of the fields. 

Fig. 1: Stripe rust, November 3, 2011 near Colfax, WA

In contrast to the big hotspots found in the Horse Heavy Hills region and other regions in Washington in early November, 2010, the rust infection level and distribution found yesterday were much lower.  This level of stripe rust infection is expected based on the dry weather conditions in September this year.

Stripe rust infection was found on volunteer wheat plants in the middle of October in Mt Vernon (northwestern Washington) as usual when our people were planting winter wheat nurseries.  Stripe rust was also reported by Dr. Juliet Marshall to be occurring on volunteer wheat plants in October in southern Idaho.  

Fig. 2: Stripe rust, November 3, 2011 in Horse Heaven Hills area, WA

The finding of stripe rust in winter wheat fields allows us to know the level of infection before the winter, which will help us to predict disease situation for the next year.  There is no action for growers to take for most of the regions in the PNW until next February or March, except for selection of spring wheat cultivars to grow in next spring (resistant cultivars should be always considered anyway).  As the weather starts getting cold, stripe rust spores on the leaf surface will be killed and the fungus will sleep as mycelium within the infected but not sporulated leaves during the winter.  Some of the sleeping rust mycelia may be killed by harsh winter and some will survive.  The level of the survival will depend on how cold and how much snow-cover during this winter.  A recent weather prediction says that this winter for the PNW will be colder than normal (http://www.weather.com/outlook/weather-news/news/articles/late-fall-winter-outlook_2011-10-24).  If, this prediction will be true, we should not have stripe rust as bad as this year.  We will wait to see how cold the winter will be and have our first forecast in February for stripe rust in the PNW next year.  People in the south-central states may need to check for stripe rust earlier as that weather prediction indicates a warmer winter.