Situation Update: Ug99 lineage races TTKSK (Ug99), TTKST (Ug99+Sr24) and TTTSK (Ug99+Sr36) confirmed in Tanzania
Three variants in the Ug99 lineage have been confirmed in stem rust samples collected in Tanzania during August 2009 by a team of Tanzanian and international scientists. Races confirmed by the USDA‐ARS Cereal Disease Laboratory, St. Paul, MN, USA were; TTKSK (Ug99), TTKST (Sr24 variant of Ug99) and TTTSK (Sr36 variant of Ug99). Races TTKSK and TTTSK were present in samples from the Hanang, and Ngorongoro areas, whilst race TTKST was present in the Karatu and Monduli areas (Lowe et al forthcoming). All three races have been present in neighbouring Kenya since 2001, 2006, and 2007 respectively. Given the close proximity of wheat areas in Kenya and Uganda known to be infected by stem rust Ug99, and observed regional wind patterns, the results from Tanzania are not unexpected. No crop damage was observed in Tanzania in 2009 due to stem rust. A combination of effective chemical control and early senescence due to drought resulted in the majority of wheat fields surveyed being rust-free apart from a few isolated infected plants. These confirmed results support previous findings which indicate the expected and continued regional spread of Ug99 variants out of Kenya.