Ug99 Means Misery for Virulent stem is on the move in and Near East

With high wheat prices and already low stockpiles of wheat, another threat is becoming ominous on the radar screen. Ug99, a virulent wheat discovered in 1999, has since traveled

across East Af- detected in had mutated from the Northern rica to , ac- one that originated in . U.S. Wheat cording to the In March 2008, the FAO reported that Food and Agri- Ug99 had been spotted in Iran, which puts culture Organi- it at the door of major wheat-producing zation of the regions. United Nations The countries east of Iran, such as Af- (FAO). USDA- ghanistan, India, Pakistan, Turkmenistan, ARS scientists Uzbekistan and Kazakhstan—all major have determined wheat producers—are most threatened by that 80% of the the , FAO says. HRS wheat So, why should this concern U.S. Sally Sologuk grown in the U.S. wheat producers and processors? The is vulnerable to speed at which stem rust multiplies may Ug99. give some perspective. When Ug99 was discovered in 1999 A rust urediospore can germinate in Uganda, it was deemed capable of de- in less than an hour and send out a germ Ug99 stem rust infects wheat stalks stroying most previously disease-resistant tube that can be inside the wheat plant with what scientiests call shocking wheat varieties. Shortly after that, it was in six hours or less, according to E.C. speed. found in Kenya and . Stakman, a former University of Min- By early 2007, FAO scientists indi- nesota plant pathologist and the lead- cated that the wheat disease had jumped ing authority on wheat stem rust dis- from East Africa to in the Arabian ease during the rust epidemics of the Peninsula and probably had spread into 1950s. . With shocking speed, the rust tubes Scientists also reported that the Ug99 will grow parasitically to produce a new “The new strains of stem rust are much more danger- ous than those that, 50 years ago, destroyed as much as 20% of the American wheat crop.” Nobel Peace Price Recipient

crop of 50,000 to 450,000 urediospores within a week to ten days. As the scientific world came to under- stand the possibility of this impending calamity, the Global Rust Initiative was organized. It was later replaced by the Borlaug Global Rust Initiative (BGRI), chaired by Dr. Borlaug, Nobel Prize win- ner and Distinguished Professor of In- Response No. 341 34 Second Quarter 2008 MILLING JOURNAL for wheat stem rust fungus ( commonly deposit particulate material graminis) that will detect one or two (like spores) through rain. We have found spores. However, this assay is general and that by looking at rain samples we can “We know that there are what we want to know is if the spores monitor the movement of rust spores several pathways in which are not only P. graminis, but also is it across the North American continent,” Ug99?” he concludes. spores are regularly trans- Szabo continued, “This assay would Efforts are underway in many wheat be used to monitor across the wheat-grow- breeding programs to develop varieties ported through the atmo- ing areas to monitor wheat rust spores with long-term resistant to the fungus. sphere from Africa and Asia coming into the U.S. We know that there “I already sent some durum mate- are several pathways in which spores are rial to Kenya for testing,” says Dr. Elias into the U.S. regularly transported through the atmo- Dr. Les Szabo sphere from Africa and Asia into the U.S. USDA ARS Cereal Disease Lab “These long distant transports most Sologuk continued on p. 36

ternational Agriculture, Department of Soil & Crop Sciences, Texas A&M Uni- versity, College Station, TX. “The new strains of stem rust are much more dangerous than those that, 50 years ago, destroyed as much as 20% of the American wheat crop,” states Borlaug in an Op-Ed for the New York Times, April 26, 2008. “Today’s lush, high-yielding wheat fields on vast irrigated tracts are ideal en- vironments for the fungus to multiply, so the potential for crop loss is greater than ever,” he writes. The Bill and Melinda Gates Founda- tion gave $26.8 million to Cornell Uni- versity for a new global project to fight wheat stem rust disease. The Durable Rust Resistance in Wheat project, launched on April 2, 2008, will bring together 15 part- ner institutions to combat the emergence of deadly new variants of stem rust.

Molecular Assays Dr. Les Szabo, Research Geneticist, USDA ARS Cereal Disease Lab in St. Paul, MN, is working on developing a se- ries of different molecular assays for de- tecting Ug99. “The first is a general assay for the rapid identification of Ug99 race clus- ter,” he explains. “This assay will be de- signed for the use of regional and state plant diagnostic clinics to test infected wheat or for Ug99 race cluster. The second set of assays will be to identify specific members of this race cluster. At present, we know that there are three members of this cluster.” “The final, and the most sensitive, will be to develop an assay that is specific to Ug99 race cluster that we can use for en- vironmental samples, such as rain,” Szabo said. “We have developed a general assay Response No. 351 MILLING JOURNAL Second Quarter 2008 35 “In early June, 1953, it was calculated that there were 4,000 tons of urediospores, with about 150 billion spores per pound, on four million acres of wheat in northern Oklahoma and south-central Kansas. Winds Ug99 stem rust has spread throughout eastern Africa and is now working carried spores northward its way across theMiddle East to Iran and possibly India. from this area into the Da- kotas and Minnesota.”

E.C. Stakman were initially resistant are breaking eties with some resistance have been iden- University of Minnesota down. The fungus is changing, so this tified through field screening in Eastern requires continuous testing,” says Dr. Africa. Elias. “Now, USDA scientists are working with university and private sector re- Head Start on Breeding searchers to accelerate breeding efforts Elias, durum breeder at North Dakota “USDA-ARS is working with U.S. to develop more resistant varieties for the State University (NDSU), the only wheat and barley breeders to get a U.S.” public durum breeding program in the head-start on breeding for genetic re- “USDA scientists are also conduct- U.S. “Some lines were found to be sistance to Ug99,” says Kay Simmons, ing national surveys to monitor for new resistant to Ug99 and some are National Program Leader, Plant Genet- and emerging strains of cereal stem suceptible. So we have a whole range ics & Grain Crops, USDA-ARS, rusts. USDA agencies are also sharing of differences. But now they are find- Bethesda, Md. information and plans to facilitate ing that some varieties in Africa that “New sources of resistance and vari- chemical management using fungi- cides. “Importantly, U.S. scientists are col- laborating with international research centers and disease experts to try to con- tain the spread of Ug99,” concludes Tough Simmons. Rugged Past Losses Convertible Gates The U.S. experienced significant crop losses during the stem rust epidemics of the early decades of the 1900s, especially during the 1950s. According to Dr. Stakman, “In early June, 1953, it was calculated that there were 4,000 tons of urediospores, with about 150 billion spores per pound, on four million acres of wheat in north- ern Oklahoma and south-central Kan- ᭿ Manual rack & pinion sas. Winds carried spores northward ᭿ from this area into the Dakotas and Air operated Minnesota, where they were deposited ᭿ Electric rack & pinion at the rate of 3.5 million an acre in an PO Box 256 • Hortonville, WI 54944 area comprising 40 thousand square 800-343-3404 • FAX: 920-779-6980 • www.tom-cinmetals.com miles.” Makes you stop and think, doesn’t it? Response No. 361 36 Second Quarter 2008 MILLING JOURNAL