Uganda 99 Black Stem Rust Yue Jin Uganda 99 Black stem rust of wheat was first notice in Uganda in 1999. It is spread by wind and passes its heterecious stage in the ample Berberis species in the region. It has spread quickly into Yemen and Iran, threatening the immense wheat production areas of Pakistan, India, and China. Yue Jin

Uganda 99 Wheat Rust Epidemiology 2001 Kenya 2003 Ethiopia 2007 Yemen IRAN 2008 Cyclone Gonu hit the Arabian Peninsula on June 8, 2007 http://www.news.cornell.edu/stories/April08/WheatRustExplainer.kr.html http://environment.newscientist.com/channel/earth/mg19425983.700-billions-at-risk-from-wheat-superblight.html http://www.eurekalert.org/pub_releases/2008-03/ns-kfs031208.php 2008 Iran

Uganda 99 Black Stem Rust Stem rust fungus is the most feared wheat disease Wind born Produces 100 billion urediospores per hectare Can destroy a crop of wheat in 3 weeks Outbreaks of stem rust hit North America in 1905, 1916, and 1953-1955 Extensive USDA and CIMMYT resistance breeding 1999 in Uganda a new race appeared: Ug99 Spread into Sudan, Ethiopia, Yemen, and Iran http://www.news.cornell.edu/stories/April08/WheatRustExplainer.kr.html The last major outbreaks of stem rust occurred in North America between 1950 and 1954, when losses approached 40 percent of the spring wheat production in some years. Since then, with the exception of a few smaller outbreaks, "Wheat stem rust [has] dropped off the radar screen completely," said Ward. "We have a whole generation of plant breeders who don't even know what it looks like." But to the horror of breeders in a Ugandan nursery in 1999, Ug99 pustules were found covering wheat varieties carrying genes that stem rust had never defeated before. "We now know that Ug99 defeats more of the known stem rust resistance genes than [in] any other [previous] stem rust race," said Ward. In a fight against time, plant breeders are working to develop and test new wheat varieties at national research facilities in the Rift Valley in Kenya and in Ethiopia, the only places where field testing with Ug99 is safe. Using traditional plant breeding (as opposed to transgenic engineering), breeders are using the research facilities to accelerate the creation and distribution of resistant wheat varieties. Poor farmers in Ug99's path who cannot afford fungicides or crop losses are especially dependent on the fruits of wheat breeders' labors. The solution, according to Ward, is no small task. "It sounds extraordinary to say, but what we need to do is replace much of the wheat in the world with wheat that is resistant to this race of stem rust," he said.

Life Cycle of Puccinia graminis Aecium 2N Aeciospores 2N (infects wheat) (sexual recombination) Life Cycle of Puccinia graminis Berberis Leaf Spermogonium (two mating types Uredospores 1N Basidiospores 1N (two mating types) to Berberis Teliospores 1N photos courtesy of the University of Hawaii

Berberis vulgaris – Barberry Alternate host for Puccinia graminis Includes genera: Berberis Mahonia x Mahoberberis over 500 species Albert Roodink Native to Eurasia Brought to North America as a medicinal and culinary plant Anton de Bary proved that it as the alternate host for cereal rusts in 1865 Eradication programs in the US, including 2 native species http://en.wikipedia.org/wiki/Berberis De Bary did a thorough investigation on Puccinia graminis, the pathogen of rust of wheat, rye and other grains. He noticed that P. graminis produced reddish summer spores called "urediospore", and dark winter spores called "teleutospores". He inoculated sporidia from the winter spores of the wheat rust on the leaves of the "common barberry" (Berberiso vulgaris). The sporidia germinated and led to the formation of aecia with yellow spores—that was the familiar symptoms of infection on the barberry. De Bary then inoculated aecidiospores on moisture-retaining slides, then inoculated these to the leaves of seedling of rye plants. In time, he observed the reddish summer spores appeared in the leaves. The sporidia from the winter spores germinated, but only on barberry. De Bary clearly demonstrated that P. graminis required different hosts during the different stages of its development (a phenomenon he called "heteroecism" in contrast to "autoecism", when development take place only in one host). De Bary’s discovery explained why the eradication of the barberry plants had long been practiced as a control for rust. Wikipedia Zereshk - Dried fruit of B. vulgaris, a much favored delicacy of Iran

Berberis vulgaris In 1920, the USDA Barberry eradication program began jaki good WY 1990 Barberry distribution in US & Canada Birds are the number one vector of Barberry seed. The states in the eradication survey have to keep checking to see if Barberry stands have been re-established by bird transmission of the seed or by dormant seeds in the soil germinating. Wyoming was added to the survey in 1990 Barberry quarantine area of the United States In 1920, the USDA Barberry eradication program began a farm to farm survey covering 750,000 sq miles. By 1933 over 18 million bushes had been destroyed. Canada began its program in the Prairie Provinces in1910