Wheat Stem Rust Situation Update: High Incidence and Severity of Stem Rust in Lowland Zimbabwe
Survey updates – Southern Africa
Mozambique: Wheat rust surveys were undertaken by IIAM, Mozambique and FAO in the key wheat growing areas of Manica and Tete provinces, Central Mozambique during the period 26th August - 1st September 2010. Wheat in Mozambique is grown in dispersed, small plots typically in remote highland areas. The Tsangano region bordering Malawi contained the highest density of fields. A total of 24 wheat fields were surveyed using standardized methodology. Wheat stem rust was not widespread and only positively recorded at one site; Rotanda, in Sussendenga district. Here a tall local wheat variety (Sitsonko) showed a highly susceptible reaction. It was noteworthy that virtually all farmers in Mozambique were growing the same variety; SC Nduna.
Zimbabwe: Wheat rust surveys were undertaken by the Crop Breeding Inst, SeedCo and FAO in the key wheat growing areas of Zimbabwe during the period 4th-9th September 2010. A total of 27 wheat fields, distributed throughout the main agro-ecological zones, were surveyed using standardized methodology. Wheat stem rust was recorded at 12 of the 27 survey sites, being much more prevalent and widespread than in the previous 2009 season. Stem rust was widespread in the Lowveld, with 8 out of 9 Lowveld sites (elevation below 800m) recording the disease. High or moderate stem rust severity (>20%) was recorded at 6 of these Lowveld sites. Highly susceptible reactions were observed on improved varieties such as SC Stallion. Very high incidence and severity of stem rust was recorded at Chisumbanje Research Station (Photo). Trace amounts of stem rust were also recorded at 4 highveld sites (Gwebi VTC, Rattray Arnold, Kadoma, Nyanga). Stem rust samples were collected at all sites where the disease was present. Until completion of the laboratory analysis the actual identity of stem rust pathotypes present in Zimbabwe is unknown. Given the recent (2009) confirmation of Ug99 lineage race PTKST (combined virulence to both Sr31 and Sr24) in South Africa, identification of the Zimbabwe pathotypes is a high priority.
Survey updates - Caucasus and Central Asia
Additional survey data were received from Azerbaijan and Tajikistan. In Azerbaijan, stem rust was absent from 24 fields surveyed in April 2010. In Tajikistan, 39 fields were surveyed using standard methodology in May 2010. Stem rust at high severity was recorded at 2 sites close to the border with Uzbekistan. Stem rust pathotypes present in Tajikistan are currently unknown.
Details of all surveys can be found in the country survey maps.