T. Gulya1, B. Hulke1, G. Seiler1, Z. Talukder2, M. Gilley2 , J T. Gulya1, B. Hulke1, G. Seiler1, Z. Talukder2, M. Gilley2 , J. Rasmussen22 , C. Misar1 , and R. Schafer 3   1USDA-ARS Sunflower & Plant Biology Research Unit, Fargo, ND; 2North Dakota State University Depts. of Plant Science and Plant Pathology, Fargo, ND; 3Central Lakes College, Staples, MN A Decade of Progress with Improving Sclerotinia Head Rot and Stalk Rot Resistance in Sunflower Collaborators with the Fargo ARS Sunflower Unit include Drs Laura F. Marek (A – Iowa State), Charlie Block (B – USDA Plant Int. Station, Ames, IA), Mike Boosalis (C – U Neb Lincoln, emeritus), Bob Harveson (D- U NEB, Scottsbluff), Bob Henson (E – NDSU- Carrington; deceased), Khalid Rashid (F- Ag Canada, Morden, MB), Michael Wunsch (G- NDSU-Carrington; and Jim Steadman (H- U Neb- Lincoln) Thanks to these scientists and their technicians! USDA Scientists (Fargo) involved in the Sclerotinia project during the last decade include : Jerry Miller (A: geneticist, retired), Brent Hulke (B: geneticist) , Chao Chen Jan (C: cytogeneticist), Lili Qi (D: molecular geneticist), Gerald Seiler (E: botanist) , and Tom Gulya (F: plant pathologist). Not pictured: Jinguo Hu, previous molecular geneticist. The mission of the Fargo-based USDA-ARS Sunflower research group is to develop germplasm with improved yield & quality characteristics. Disease resistance has been a major criteria for the unit since the 1970s. With the creation of the USDA Sclerotinia Initiative, our unit has received competitive funds to allow us to accelerate our efforts to find resistance to both head rot and stalk rot caused by Sclerotinia sclerotiourum. Accomplishments during the past decade have included: Shift from relying upon natural infection to artificial inoculation Annual production of 400 to 800 lbs of Sclerotinia-infected millet to inoculate 1500-2000 rows of stalk rot evaluations at two to four locations in ND and MN. Creation of two head rot nurseries with automated mist irrigation (Carrington, ND and Staples, MN) to ensure good development of head rot. Nearly complete phenotyping of USDA Sunflower germplasm collection (1500 cultivated sunflower and ~ 3000 wild annual and perennial Helianthus accessions) in field and greenhouse trials for stalk rot. Head rot phenotyping in progress. Of 90 inbred line/germplasms released during last decade, 40 releases were either primarily selected for head rot or stalk rot resistance, or had improved levels of resistance. Several releases had multiple disease resistance (i.e. rust and downy mildew) and combined high oleic oil and herbicide resistance. Work currently in progress: Seed collection of wild Helianthus species not currently represented in National Plant Germplasm collection. (Gerald Seiler and Laura Marek) Transferring stalk rot resistance from six annual Helianthus species into cultivated. (Lili Qi and post-docs) Transferring stalk rot resistance from 15 wild perennial Helianthus into cultivated. (C C Jan and post-docs) Association mapping and molecular markers for Sclerotinia head rot, Sclerotinia stalk rot, and Phomopsis stem canker (Brent Hulke and Z. Talukder) Cultivated germplasm acquisition from foreign public collections (Russia, South Africa, Turkey) to assess Sclerotinia resistance (Tom Gulya and Gerald Seiler) Improvement of ascospore production method and documentation to share with Sclerotinia community (T. Gulya, M. Boosalis, B. Harveson, J. Steadman, M. Wunsch. A F E B C D G H A B F E D C F Technical support to the USDA Sclerotinia project during the last decade provided by the following people from Fargo: Scott Radi, Nikolay Balbyshev, Megan Ramsett, Michelle Gilley, Chris Misar, Lisa Brown, Marjorie Olson, Theresa Gross, Leonard Cook, Angelia Hogness, Dale Rehder, LeAnne Mathiesen, Dana Weiskopf, Arun Jani, Brenda Fradet, and Marcia Meyer, plus technicians at University of Nebraska-Lincoln and Scottsbluff, NDSU Research & Extension Centers at Carrington and Oakes, ND, Iowa State University and the USDA Plant Introduction Station, Ames, IA. The following post-doctoral scientists have worked on the Sclerotinia project, under supervision of USDA-ARS scientists. Under Dr. Brent Hulke: Zahirul Talukder. Under Dr. Jinguo Hu: Bing Yue and Junfeng Chen. Under Dr. Lili Qi: Yunming Long. Under Dr. C. C. Jan: Jiuhuan Feng, Zhao Liu, Fang Wei, Jichong Zhang and Hongzia Wang.