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Rust Report - Stem (Black) Rust

Regularly updated situation reports on cereal rusts based on information provided by a global network of rust workers. It is important to note that not all reports of stem rust relate to Ug99 or variants - other local races are also included.

Survey Updates - East Africa

23 Jul 2010

Survey updates – East Africa

Kenya: Stem rust incidence and severity is very high in Kenya. Recent surveys (June 2010) by KARI,Njoro staff in the Narok region recorded stem rust in 80% of the 109 fields surveyed. Stem rust severity was recorded as moderate (20-40%) or high (>40%) in 33% of the survey fields. Extremely susceptible reactions (80-100S) were recorded in 5% of the survey fields. From the survey, 90% of the fields were considered to have received some fungicide application. Reports from the field indicate that farmers who have not sprayed, sprayed late, or used incorrect dosages are experiencing crop losses. Following above normal rainfall in recent months, conditions appear conducive for disease development.

Uganda: Surveys were undertaken by Buginyanya Zonal Agricultural Research and Development Institute and FAO in July 2010. A total of 25 fields were surveyed in Kapchorwa district (east) and Kabale / Kisoro districts (south-west), Uganda. Stem rust was recorded in 64% of the fields surveyed. Highest incidence and severity was recorded in Kabale district, with only trace amounts and low incidence detected in Kapchorwa district. Bread wheat, barley and triticale were all observed with susceptible reactions; however any losses would be minimal due to the advanced stage of most crops. Current race composition in Uganda is unknown, but samples were collected for future race analysis.

 

Survey updates - Middle East, Caucasus, and Central Asia

Surveys were undertaken in Azerbaijan (May/June 2010 – 38 fields), Lebanon (May 2010 – 16 fields) and Uzbekistan (May 2010 – 56 fields). In each country, isolated occurrences of stem rust were detected in farmer’s fields. In Lebanon, occurrence of stem rust at 11 of the 16 survey sites was considered slightly unusual. In Azerbaijan, stem rust at two on-farm sites (score 20SMS, 40SMS) on the Caspian Sea was noteworthy. In Uzbekistan, stem rust (score 40MS) was recorded at a single site in the Fergana Valley. In all cases races involved are currently unknown. Increased surveillance effort may be one factor leading to increased detection, but regular future monitoring and confirmation of races involved is considered important.

 

Details of all surveys can be found in the country survey maps.

   

Wheat Stem Rust - Previous Report

9 Jun 2010

Latest confirmed race analysis results

Confirmed results from race analysis completed in the 2009/10 season are now available. The confirmed spread of Ug99 variants carrying combined Sr31 + Sr24 virulence in Africa continues, along with the continued predominance of these variants in Kenya. The absence of Ug99 from samples collected in Pakistan in 2009 was also confirmed.

 

In Ethiopia, two isolates collected near Meraro in the Rift Valley during October 2007 were confirmed to have combined virulence to both Sr31 and Sr24. Samples were collected by EIAR scientists and analysis undertaken by the Cereal Research Centre, Winnipeg, AAFC, Canada. The race was postulated to be PTKST. This represents the first confirmed occurrence of a Ug99 variant with virulence to Sr24 in Ethiopia.

 

In Kenya, a total of 55 samples were collected in 2009 by KARI scientists but race analysis was only possible on 12 viable samples. Race analysis was undertaken by the Cereal Research Centre, Winnipeg, AAFC, Canada. Races identified were; TTKST (Ug99+Sr24) (50%), PTKST (34%), and PTKSK (16%). Despite the low sample size, the results did indicate the continued predominance of Ug99 variants with combined Sr31 + Sr24 virulence in Kenya (Wanyera et al 2010).

 

In Pakistan, samples were collected during the 2009 season from Sindh and lower Punjab. Isolates were analysed at Murree in Pakistan and at the Cereal Research Centre, Winnipeg, AAFC, Canada. All isolates tested were identified as race RRTTF. This race has also been previously identified in Ethiopia (2007) and in Yemen (2007, 2008). RRTTF has reported virulence on Sr13, Sr36 and SrTmp. It is avirulent on Sr8a, 9e, 22, 24, 25, 26, 27, 31, 32, 39, 40. Preserved urediniospores were also sent to PBI, Uni Sydney, Australia for DNA fingerprinting for Ug99 and negative results were obtained. Combined analyses indicate the absence of Ug99 in the 2009 Pakistan stem rust samples (Mirza et al 2010).  

   
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Rust SPORE is developed by FAO and partners as part of the Borlaug Global Rust Initiative (BGRI) to mitigate the threat of wheat rust diseases (stem rust, leaf rust and yellow rust).

Disclaimer

The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

Latest Updates

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2010 Rust Surveys - Stem Rust Severity (Click to access smart PDF)
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Wind Trajectories 25/02/2011 (Click for larger view)