Pests
Stripe Rust
Stripe Rust Updates
Stripe rust reports
Stripe rust was reported in barley nurseries near Corvallis on April 5th and in Mt. Vernon Washington (northwestern Washington) with up to 40% severity on April 12th. These sightings were in nurseries on varieties known to be susceptible to stripe rust. As of April 20th stripe rust was detected in Walla Walla and in the Horse Heaven Hills on the Washington side of the Columbia River. These were small areas in early planted fields.
Spring wheat susceptibility
Chen also reminds us that some spring wheat varieties, such as Hank, WPB 926, Tara, IDO377s, and some others that were resistant to stripe rust before 2005 will be more vulnerable to stripe rust this year. This change is due to the susceptibility that developed last year and that races infecting these cultivars last year will be predominant again this year.
Cultivars like Alpowa and Louis should be fine this year with their durable high-temperature adult-plant resistance and with the later arrival of the rust. Spring barley will generally have less stripe rust pressure than spring wheat. Barley varieties Baronesse and Bob have durable high-temperature adult-plant resistance to stripe rust.
Stripe rust rating
Check stripe rust ratings in the Washington State Seed Buyer's Guide for resistant and moderately resistant varieties of both spring and winter wheat at http://www.wscia.com/.
Stripe Rust developing rapidly in the Pacific Northwest
Good moisture in the past three weeks improved the winter wheat crop outlook, but also favored the development of stripe rust in the region. This year, stripe rust showed up much earlier than last year and earlier than normal. This is due to the warmer weather over the winter months. Xianming Chen, WSU, recently said that wheat and barley stripe rusts were reported as early as the first week of February near Corvallis and have developed rapidly in western Oregon.
On April 20, Chen found stripe rust just showing up on susceptible checks in the disease-monitoring nursery at the Pendleton Station, while at the Hermiston Station, stripe rust up to 5% was easily found on several entries in the disease- monitoring nursery and other nurseries. Near Walla Walla, WA, stripe rust was more severe where the susceptible check, 'PS 279', had up to 40% stripe rust. He was able to take stripe rust notes throughout several nurseries in that field.
Chen notes that this is the earliest time he has found stripe rust near Walla Walla. The susceptible check, 'Lemhi', in the spring nurseries, which were planted next to the winter nurseries, and the plants were just at the three-leaf stage, also had stripe rust. A commercial field just outside of Walla Walla to the north had 20% stripe rust throughout the field. Plants in hot spots had up to 40% rust. The early start of stripe rust is, as forecasted based on the rust situations last year, and the weather conditions in the last fall and winter, especially the temperatures higher than normal in last December and January.
Perspective stripe rust impact and control
Stripe rust reactions in disease monitoring nurseries at Walla Walla and Hermiston, and rust samples from Corvallis, indicate stripe rust races are the same or similar to those detected last year in the Pacific Northwest according to Chen. Based on this information, growers should expect that wheat varieties that were resistant or susceptible last year would be resistant or susceptible this year.
Disease pressure has been lessened this year in areas heavily impacted last year as growers elected to plant resistant cultivars such as Stephens, Madsen and Eltan. So the good news is if you planted a resistant variety of winter wheat strip rust damage should be minimal in the winter crop. If you planted a susceptible variety such as Hatton, Buchanna and Weston you should plan on spraying with a fungicide as soon as possible. Hopefully if you seeded spring wheat you choose resistant varieties, if not get prepared to use fungicides, because with the early development of stripe rust it will develop even quicker when the weather get warmer in the next several weeks. Chen suggested that two applications of fungicide might be needed for susceptible winter and spring crops this year.
