2015
Virulence of isolates of the soybean stem canker fungus from disease nurseries in GA
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Contributor/Checkoff:
Alabama Soybean Producers
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
James Buck, University of Georgia
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Alabama Soybean Producers
(n/a)
Institution Funded:
University of Georgia
(n/a)
Brief Project Summary:

Southern stem canker, caused by the fungus Diaporthe aspalathi, can be a devastating soybean disease. The fungus survives on infected soybean residue with infective conidia or ascospores produced early in the spring. Cultivar resistance to stem canker is conditioned by at least five dominant resistance genes. This research aims to improve the in-vitro toothpick stem canker inoculation assay to make it easier to do on genetic materials. It also intends to assess the virulence of Diaporthe aspalathi from three disease nurseries on multiple soybean cultivars. The long-term goals of the proposed research are to streamline the green-house assay to allow for future mapping projects.

Key Benefactors:
farmers, agronomists, Extension agents, soybean breeders, seed companies, geneticists

Information And Results
Project Deliverables

Final Project Results

2014 progress report: Stem samples were collected fall of 2014 from each disease nursery. Stems were sectioned, surface disinfested and plated on acidified potato dextrose agar. Isolates will be identified to species level using ITS sequence generated by PCR using primers ITS1 and ITS4. Two isolates of Diaporthe aspalathi have been identified based on a BLAST search of the NCBI da-tabase. An additional 25 Diaporthe-like isolates await identification.

Advanced breeding materials from the soybean program and also state entries in the variety testing program were evaluated for stem canker in nurseries in Plains, Griffin, and Calhoun. 2014 plantings included three replicate blocks each of 40 lines in the UT/UPT test and 36 lines each in the XT1, XT2 and XT3 tests. Disease pressure was highest in Calhoun with average stem canker ratings for "Hutton" and "G81-2057" of 6.1 and 7.7, respectively (10 point scale) compared to 2.7 for both in Plains.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.