The emergence of Ug99 races of the stem rust fungus is a threat to world wheat production.

@article{Singh2011TheEO,
  title={The emergence of Ug99 races of the stem rust fungus is a threat to world wheat production.},
  author={Ravi Prakash Singh and David Hodson and Julio Huerta-Espino and Yue Jin and Sridhar Bhavani and Peter Njoroge Njau and Sybil A. Herrera-Foessel and Pawan Kumar Singh and Sukhwinder Pal Singh and Velu Govindan},
  journal={Annual review of phytopathology},
  year={2011},
  volume={49},
  pages={
          465-81
        }
}
Race Ug99 of the fungus Puccinia graminis tritici that causes stem or black rust disease on wheat was first detected in Uganda in 1998. Seven races belonging to the Ug99 lineage are now known and have spread to various wheat-growing countries in the eastern African highlands, as well as Zimbabwe, South Africa, Sudan, Yemen, and Iran. Because of the susceptibility of 90% of the wheat varieties grown worldwide, the Ug99 group of races was recognized as a major threat to wheat production and food… 

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