Location: Sunflower and Plant Biology Research2013 Annual Report
1a. Objectives (from AD-416):
Evaluate commercial sunflower hybrids and experimental lines for improved resistance to Sclerotinia head rot.
1b. Approach (from AD-416):
Sunflower hybrids and advanced experimental lines with expected resistance or tolerance to Sclerotinia head rot will be solicited from sunflower seed companies and breeding programs. Two sets of screening nurseries will be developed, one to screen new hybrid lines that have not been publicly evaluated and another set of hybrids to confirm the resistance that was previously defined. The new hybrid lines will be compiled into the “initial screening” which will include about 75 entries and be planted at Carrington, ND, and Morden, Manitoba. The most promising hybrids identified in initial screenings conducted in 2010 will be compiled into the “repeat screening” which will include about 25 entries. The “repeat” test will be planted at Carrington, Langdon, and Oakes, ND; Morden, Manitoba; and Crookston, MN. In all screenings, each hybrid will be established in plots one-row (30-inch) wide by 25 ft long and arranged in a randomized complete block with four replications. Sunflower heads will be inoculated with ascospores at the R5 growth stage (flowering). To accommodate differential development within and among hybrids, inoculations will be made on multiple days. Misting systems will be constructed, and misting will be initiated at flowering and continued as necessary to promote disease. Sunflower head rot incidence and severity will be scored at a minimum of two timings, and approximately 15 heads will be assessed per plot.
3. Progress Report:
This project was initiated on July 1, 2011, research is complete, and the overall objectives of this project were to identify sunflower cultivars which are less susceptible to Sclerotinia head rot, to study chemical and biological control options for managing this disease, and assist ARS with technology transfer. Over the past several years, we have contributed to the documentation of significant, repeatable differences that exist in the susceptibility of sunflower hybrids to Sclerotinia head rot. We have assessed the Sclerotinia head rot resistance of new commercial hybrids as those hybrids have been introduced into the market, thereby providing growers with independent data on the Sclerotinia head rot resistance of commercial hybrids. We have also played a role in the development of new hybrids with improved Sclerotinia head rot resistance by screening sunflower breeding lines and elite experimental hybrids for their resistance to Sclerotinia head rot. Finally, in collaboration with others, we have been successful in developing inoculation procedures and misting systems that reliably produce the moderate to high levels of Sclerotinia head rot infection that are needed to identify the relative susceptibility of sunflower hybrids to Sclerotinia head rot. Sunflower growers now are able to review the results of the field trials associated with the project to identify and select commercial hybrids that have improved resistance to Sclerotinia head rot and stalk rot. This project also supported the ninth annual meeting of the Sclerotinia Initiative which was held in Minneapolis, MN, in January 2013, and through that effort contributed to further development/refinement of the National Sclerotinia Initiative website http://www.ars.usda.gov/Research/docs.htm?docid=20122 News items, meeting posters, publications, and related topics of interest to the Initiative are regularly updated and/or added to the site. Additionally, working cooperatively with representatives of several commodity organizations and educational institutions, educational brochures highlighting the Initiative and related technological advances were further developed and made available in hard copy and on-line versions. The on-line versions can be accessed and printed directly from the website. The website continued to host white mold risk indices for canola, soybean, dry edible bean, pea & lentil and sunflower. These indices provide growers, extension agents, crop consultants, and researchers a method to assess the production risk to their crops related to this important disease. Links to canola disease risk maps are also provided for grower information. The Sclerotinia Initiative Strategic Plan was updated and made available as was a Sclerotinia Initiative Annual Report of Progress (2012).