2007 U of M Research Special Report

Field and Greenhouse Evaluation of Breeding Lines for Resistance to Major Foliar Diseases

The use of resistance in the host plant is the most economic and environmentally friendly method for controlling most plant diseases. University of Minnesota plant pathologists Ruth Dill-Macky and Brian Steffenson, have been working at the St. Paul campus to assist the plant breeding programs led by Jim Anderson (wheat) and Kevin Smith (barley) to improve the resistance of wheat and barley to multiple diseases important to Minnesota.

These plant pathologists screen material in St. Paul, and at other locations in Minnesota, for their response to the foliar diseases of wheat and barley such as tan spot and Septoria tritici blotch (STB) of wheat, and net blotch, Septoria speckled leaf blotch (SSLB), spot blotch and stem rust of barley.

The breeding efforts aimed at improving FHB resistance led to the introduction of many new wheat and barley lines into the breeding program. While this was essential to improve the FHB resistance, susceptibility to other diseases previously controlled effectively through host resistance (e.g. leaf rust and stem rust) has been diluted in the Minnesota breeding programs by the addition of this new material. 

To ensure that cultivars susceptible to any of the common diseases in Minnesota are not inadvertently released for commercial production, it is essential that all advanced breeding lines be rigorously screened for resistance to all the major diseases that occur in the region. For this reason, field and greenhouse evaluation of advanced breeding lines from the wheat and barley improvement programs for resistance to the major foliar diseases is an ongoing activity for these plant pathologists.

The screening conducted in 2006 included:

Fusarium Head Blight (FHB) - wheat and barley. Screening was conducted at three Minnesota locations (St Paul, Morris and Crookston). Each year as much as 400 liters of Fusarium inoculum (fungal spores suspended in water) is produced for use in the inoculated and irrigated nurseries at St Paul and Morris. Dryland nurseries are also established for barley at St Paul and Crookston. These nurseries are inoculated but not irrigated and provide additional information on disease development under conditions more like those of commercial crops. The pathology group also assisted in the greenhouse evaluations of lines, although fewer lines are being screened now compared to past years as the breeding programs have shifted their screening emphasis to the field nurseries. Identification of resistant material has enabled the breeding programs to make significant progress in breeding for FHB resistance.

Net Blotch - barley. Approximately 1,000 barley entries are tested annually as seedlings for their reaction to the net blotch pathogen in the greenhouses on the St. Paul campus.  Approximately 40% of the lines tested exhibited resistance and were advanced in the breeding program.

Septoria speckled leaf blotch (SSLB) – barley. Breeding lines were evaluated in the greenhouse as seedlings at St. Paul.  Of the entries tested, approximately 50% appeared resistant. Resistant lines with good agronomic characteristics are being advanced in the breeding program.

Spot blotch - barley.  Entries were planted for spot blotch evaluation at St. Paul with over 90% of the entries tested exhibiting resistant reactions.

The evaluation of wheat and barley breeding lines for multiple disease resistance is a collaborative effort between Dill-Macky and Steffenson in St. Paul and Char Hollingsworth at the Northwest Research and Outreach Center, Crookston. As the pathology and breeding groups work collaboratively on many nurseries in the Red River Valley, this report contain details of nurseries conducted cooperatively at multiple locations throughout the state.

This work facilitates the development of wheat and barley cultivars with multiple disease resistance and will ultimately increase the sustainability of the production of small grains in Minnesota.

– Dr Ruth Dill-Macky, ruthdm@umn.edu and Dr Brian Steffenson, bsteffen@umn.edu   plant pathologists, University of Minnesota