OSU Cereal Central is all about getting the knowledge a grower needs for growing wheat, barley, canola, and other cereals in the dryland farming region of the Pacific Northwest. It is an educational effort of OSU Extension.
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
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.
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 15th, 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.
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.
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.
Dr Chen, USDA ARS in Pullman, shared the following table: Stripe Rust losses with and without fungicide
last winter. This experiment was conducted in the Pullman, Washington area under natural infection conditions in 2010. The table shows that Tubbs and Xerpha losses in the 23-26% range.
Mike Flowers, Chris Mundt, Larry Lutcher and Mary Corp, of Oregon State University, provided the following information in their Stripe Rust Seminar this morning. The webcast seminar connected 8 sites across eastern Oregon with over 30 growers and crop consultants in attendance to learn the latest update on stripe rust conditions across the wheat growing regions of the Columbia Plateau and central Oregon. Here are some of the topics covered:
Stripe rust pressure continues to build across the region, but the answer to the dilemma is in the details of each grower’s field conditions, stage of growth and wheat variety susceptibility to stripe rust. Growers are faced with questions both about what is currently happening in their fields and then also what are their best options for seeding this fall. OSU Extension webcast this morning focused on these two key questions for wheat growers across the Columbia Basin: Do I need to treat a second time for stripe rust? And what wheat variety should I be planting in the fall of 2011?
Both questions center on the level of susceptibility of the various wheat varieties and the current strains of strip rusts being seen in fields. Mike Flowers, OSU Cereal Specialist, noted that he sees about three grouping of varieties –
Highly susceptible,
Moderately susceptible, and
Mostly resistant.
So far this year, Flowers has observed that varieties that are holding up well under dryland conditions are ORCF 101 and Skiles. This is the same result he saw last spring when stripe rust conditions were a problem. Yet it is worth noting that this year, the problems started last fall and have continued to increase under our cool wet spring conditions.
The next level of susceptibility with only moderate resistance or susceptibility, depending on if your cup is half empty or half full, are the varieties - Legion, ORCF 102 and Stephens. Finally, the most susceptible are Tubbs, Xerpha, Legacy and Goetze.
Many acres had an earlier application of fungicide applied at the same time as the herbicide. The stripe rust control provided by those applications are running out, and fields with susceptible varieties need to be closely monitored. Remember if you see 10% live spores on the leaves, then you likely have 40-50% infection as there is a 2 week delay in appearance of the spores following infection.
Flower’s summary remark at the end of today’s broadcast – was “Don’t let it (stripe rust) get ahead of you.” Many fields are currently seeing stem elongation, but don’t yet have flag leaf emergence. Plants usually show 4 joints on the stem prior to the flag leaves according to Lutcher. These plant development stages are helpful in gauging the timing of fungicide applications to maximize the control window during late spring applications. The real world realities of getting the application scheduled and finding enough good hours to get the application on the field may be a greater deciding factor about pulling the trigger for many growers especially with highly susceptible varieties to moderately susceptible varieties.
Chris Mundt, OSU Pathologist, also added the caveat that when the wheat plant reaches the flowering stage it is too late to have any affective control of the stripe rust with fungicide application so growers need to realize that if the treatment window get passed there is no benefit in continuing to treat.
Next week, we can talk more about the question of what to plant this fall,
Mary
If you have additional comments and thoughts, please post below.
