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.   

OWGL Fall Workshop for Umatilla County Growers

October 19 – Umatilla County Meeting & Dinner – Pendleton Convention Center, 5:00 pm.

The PGG Buckle Club will join us for the Social hour and Dinner following the meeting.

Topics/Speakers:

·         Forecast for the 2012 Legislative Session

·         Jana Jarvis, OWGL Lobbyist; PGG Marketing Update;

·         Dinner keynote – Blake Rowe, Oregon Wheat CEO.

All wheat producers and industry supporters are invited and encouraged to attend OWGL events. RSVP is not required,

but appreciated. Watch your mailbox and/or inbox for details and RSVP

Winter Wheat Variety Comparisons

The following table combines stripe rust disease readings from the Oregon Statewide Elite Variety trials and yields of those same varieties at the Pendleton/Ruggs and Hermiston sites. I am highlighting only the most commonly planted winter wheat varieties. The complete results of disease notes and yields from the trials are available online at www.cerealcentral.com. It is interesting to note the different levels of infection at the two different sites.

I have included the 2 and 3 year averages when available – realizing that yields were impacted in 2010 and 2011 by stripe rust. 2009 was a year with low stripe rust levels and it is beneficial to include those yields in the average when available.

While weather conditions may return to drier patterns, researchers in Oregon and Washington have noted that stripe rust races have changed and so long-term we will need to respond also. Fortunately, two years have given our wheat breeders an opportunity to do some serious selections for stripe rust resistance but it will take a few years to reap the benefits and bring those selections into our production system.  

My CerealCentral website and August Newsletter provide more in depth information for your planning purposes. Enjoy!!    

Winter Wheat Stripe Rust Infection vs. Yield Comparison, 2011

    

Planting considerations Part Two

I got some reaction to yesterday's posting about which varieties one might steer away from planting because of their susceptibility to strip rust infection. The issue of variety selection is often one of that involves several considerations, but if all other things were equal - one would select the top yielding variety for the area that you grow wheat in. In Umatilla County we have long-term average yields that range from 25 bu. to 90+ bu. and our plant breeders have provided a selection of varieties for these different production areas.

When deciding which variety to plant, if for example you are in a high production area, you would probably want to select the highest yielding variety with the highest level of strip rust resistance. So perhaps you would choose Legion over Tubbs06.


This year, we were able to control the stripe rust through timely treatments with fungicides and it turned out to be a good investment. I don't have hard numbers for the acres treated in Umatilla County, but I estimate that 90% of 250,000 acres were treated once, another 40% treated a second time and maybe 25% treated a third time for a total treated acreage of about 387,000.  Treatment costs varied but even with saving the application costs by tank mixing with herbicide treatments in early spring, I estimate fungicide treatments costs growers about $3.6 million in 2011.

These additional production costs were fairly easy to swallow as prices were good and yield potential was higher than average. If these variables change, which they always do, then the choice might be harder to make.

Let me know where you think we should be headed, but long term I think we will need to look at varieties with higher levels of resistance to the current stripe rust races rather than relying on fungicides. Short term I think we are setup for a possible repeat of last fall with early infections of stripe rust, and we should plan accordingly.
 

Early winter wheat planting considerations

Hopefully, you are wrapping up harvest in the next few days! All reports I have heard have been very positive, so no one is complaining about finishing up late. Yet, with the excellent moisture conditions and the cool night time temperatures, it looks like we will be seeing significant amounts of early seeding in the area.

Early seeding likely faces two challenges this fall. One is aphids and the second is fall infections of stripe rust.

On the topic of aphids, if you are seeding early, prior to October 15^th, an insecticidal seed treatment is your best management tool to prevent aphids transmitting Barley Yellow Dwarf Virus (BYDV). Especially in areas adjacent to irrigated fields of corn, last fall, we saw a migration of aphids to early seeded wheat. Fall infections of BYDV can seriously impact yields. Typically, delaying seeding until later in the fall will reduce the level of infection due to a shorter window of opportunity for aphids to infect the plants. Fall aerial applications of insecticides can be effective, but it is challenging to get the timing right. Always scout your fields before making crop management decisions.

The second challenge that we face this fall is one we have been talking about since the field days in June – the potential for fall infections of stripe rust. Given the high inoculum levels we experienced this past growing season, and the below average temperatures that have continued most of the summer, it is very likely we will again see fall infections of stripe rust in our area.

In our drier parts of the area, the benefits of early seeding still outweigh delaying. The only remaining option is to look at variety selection. The following list, provided by the Mike Flowers and the OSU Cereal Breeding Program, is based on their many observations across the state this past season. These varieties are the most susceptible to stripe rust and should be avoided if possible:

Soft White Winter		Hard Red Winter
AP Badger	AP Paladin
AP Legacy	Bauermeister
Goetze	Esperia
Tubbs 06	Genesi
Xerpha	UICF Grace
	WB Rimrock
	WB Tucson
	Whetstone

Fall application of fungicides for stripe rust control are not recommended as fall/winter environmental conditions may provide some levels of control. It will be important to scout fields, regardless of variety, in late February or early March, depending on growing conditions and weather. If stripe rust is found an application of fungicide is recommended, and can possibility be tank mixed with spring herbicide applications.

Thanks to Mike Flowers, OSU Cereal Specialist, for information he provided for this article.

Stripe Rust - HTAP is finally kicking in!

Mike Flowers, Oregon State University Cereal Specialist, is offering the following observations at our CBARC and Ruggs OWEYT trials.

GOOD NEWS
It appears that HTAP is finally kicking in. On many varieties it was very difficult to find active rust. Of course there were exceptions like Tubbs 06, Xerpha, and AP Legacy.
Also several varieties are showing hypersensitive reactions like OR2040726 (little to no active rust, but lots of yellow).

Growers in the area seem to have stayed on top of the rust and kept it under control (there are exceptions). Hopefully this will keep the rust load down for the remainder of the year and next fall.

BAD NEWS

The crop is late. Neither site was headed yet, which means we are 10-14 days behind.

There will be plenty of moisture for early seeding as we continue to get rain. This sets us up for fall stripe rust infections and may mean we will see another bad rust year. So variety selection this fall will be very important.
Be sure to attend one of the OSU Station Field Days near you next week to get more information on this topic and other research farming cereals in the Pacific Northwest.

Stripe rust & late growth stage applications

We are reaching, if not past in some areas, the point where fungicide applications are effective in controlling stripe rust. Remember  -applications at late growth stages (past flowering) usually do not increase yield regardless of rust level. 

Also watch your applications to insure that you don't exceed the maximum rate for the season. Also carefully read if the fungicide label is using a maximum stage of growth such as Feekes 10.5 and/or a Pre Harvest Interval (PHI) of a minimum number of days to harvest.

Hopefully, with temperatures in the 80's over the next several days we will at least have some drier and warmer conditions in the fields.

Visit CerealCentral for the latest newsletter which includes Field Day Schedules for Hermiston, Pendleton, and Moro Cereal Field Days.