Posted by John Burns 10/12/05
INCLUDED WITH THIS UPDATE:
· UPDATE: 2005 SPRING BARLEY – STRIPE RUST
· STRIPE RUST: Infection types and Severity (% infection) scales.
The attached (click here) data was provided by Dr. Xianming Chen, Plant Pathologist, USDA/ARS, Pullman, WA that lists the stripe rust evaluations for spring barley varieties included in the 2005 WSU Extension Cereal Variety Testing Program nurseries. We appreciate the support that Dr. Chen provides on conducting these evaluations. The data represents stripe rust evaluations at 5-locations in 2005. Included in the data is a listing of Infection Type (IT) {see discussion below) and Severity (%) – the percent of leaf area of a variety that is infected by stripe rust at the time of evaluation. In some situations there are two numbers separated by a comma (,) under the IT (infection type) column. When this occurs the majority of the plants of a variety have an IT represented by the first number and a few have IT represented by the second number. For example, entry 21 (2001NZ384 spring barley) is listed as: IT (5,8) and % (90) – the majority of the leaves have a type 5 (IT) infection and a few have a type 8 (IT) infection. 90% of the leaf tissue is infected with stripe rust. This is common, particularly in experimental lines where it is common to have a fairly high level of heterozygous plants. This is the message received from Dr. Chen:
Hello, everyone:
Attached (click here) is a rust data file for 2005 Spring Barley Extension Nursery coordinated by John Burns. Compared to wheat stripe rust, barley stripe rust developed much slowly because of low innoculum. However, the disease developed to 100% severity on susceptible entries, exampled by the nursery at the Spillman Farm near Pullman under natural location. A few Commercial fields grown with highly susceptible cultivars had severe stripe rust.
At the Mt Vernon location (northwestern Washington), stripe rust occurred late compared to past years, while leaf rust (Puccinia hordei) developed fast. As a result, stripe rust data were less reliable for the entries had severe leaf rust. Leaf rust occurs every year in northwestern Washington, but is hard to find in eastern PNW, the major barley growing region.
Please let me know if you have any questions.
Best wishes,
Xianming
STRIPE RUST: INFECTION TYPES: A 0-9 scale described below was used for recording infection types (ITs). Generally, an infection type (IT) from 0-4 shows necrotic symptoms with slight rust sporulation. Scores of 5-9 indicate damaging infection – the rust is continuing to develop and infect. SEVERITY (%): Severity is a percentage of the leaf area of a variety that is being infected with stripe rust. The following scale is described in: Technical Bulleting Number 1788, Virulence, Aggressiveness, Evolution, and Distribution of Races of Puccinia striiformis (the Cause of Stripe Rust of Wheat) in North America, 1968-87, Feb. 1992. Both scales are used in the data sets to depict the impact of stripe rust on varieties.
0 = no visible signs or symptom
1 = necrotic and/or chlorotic flecks; no sporulation
2 = Necrotic and/or chlorotic blotches or stripes; no sporulation
3 = Necrotic and/or chlorotic blotches or stripes; trace sporulation
4 = Necrotic and/or chlorotic blotches or stripes; light sporulation
5 = Necrotic and/or chlorotic blotches or stripes; intermediate sporulation
6 = Necrotic and /or chlorotic blotches or stripes; moderate sporulation
7 = Necrotic and/or chlorotic blotches or stripes; abundant sporulation
8 = Chlorosis behind sporulating areas; abundant sporulation
9 = No necrosis or chlorosis; abundant sporulation
Heading using the h3tag
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