ARS | Publication request: Discovery of novel sources of resistance to head rot and stalk rot in cultivated sunflower and wild Helianthus

Submitted to: ARS Sclerotinia Initiative Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 6, 2011
Publication Date: January 19, 2011
Citation: Gulya, T.J., Hulke, B.S. 2011. Discovery of novel sources of resistance to head rot and stalk rot in cultivated sunflower and wild Helianthus. ARS Sclerotinia Initiative Annual Meeting, January 19-21, 2011, Bloomington, MN. p. 21.

Technical Abstract: The 2010 growing season had abnormally high rainfall in the Red River Valley area of North Dakota and Minnesota, where many of our Sclerotinia nurseries were located. While we have successfully done field evaluations of sunflower for both Sclerotinia head rot and stalk rot for nine years, we lost virtually all of one head rot and one stalk rot nursery in 2010. Excessive rainfall eliminated stalk rot development at one of three inoculated field trials, and a severe infestation by sunflower midge, which deforms developing sunflower heads, rendering ~ 75% of a 1500 row head rot nursery data meaningless. The excessive rainfall, however, fostered Phomopsis stem canker, which enabled us to make selections for another important disease, and the midge infestation revealed some sunflower germplasm with combined tolerance to both head rot and sunflower midge. The excessive rainfall also impacted a companion project with Dr. C. Block in which we were unable to achieve stalk rot infection on wild annual sunflowers. We were able to generate good stalk rot data on 2200 rows of USDA breeding material (of 3200 rows planted at three sites) and thus progress has been made in stalk rot resistance. As a result of the continued midge infestation at the Carrington, ND research station, our entire head rot testing effort will move to Staples, MN in 2011. Field testing completed from 2008-9 in which we phenotyped 250 USDA Plant Introductions identified ~ 25 accessions with superior stalk rot resistance, and these will be planted in two locations in 2011 to assess their head rot resistance. Efforts to study the influence of root exudates from different crops on the mode of sclerotial germination in greenhouse experiments were unsuccessful and this portion of our work has been shelved. Preliminary work has begun in conjunction with Dr. Mike Boosalis (retired plant pathologist from the University of Nebraska) to define optimal parameters for large scale apothecia production. Dr. Boosalis has been producing ascospores for 20+ years for use by many Sclerotinia researchers across the U.S. and has graciously offered to collaborate with us and other U NEB scientists. The study will examine a range of Sclerotinia isolates in multiple laboratories, and the results will be published.