Organizing Committee


Poster Presentations


Poster Presentations


Viability of Phakopsora pachyrhizi urediniospores under simulated winter conditions

Presenter: S. Park

All authors and affiliations: S. PARK, N. Hazard, A. K. Chanda, and Z.-Y. Chen. Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803

Soybean rust, caused by Phakopsora pachyrhizi, originally occurred in eastern Asia and it has now spread to South America and the continental United States. Sixteen states have reported soybean rust disease on soybean or kudzu so far this year. This disease has the potential to cause severe economic losses to the U.S. soybean growers, especially in the south, where the environmental conditions are more conducive to the disease. One of the key environmental factors that determine whether the rust fungus spores could remain viable and initiate new infections in the next growing season is temperature. In the present study, we examined the viability of soybean rust urediniospores under different temperatures and simulated winter conditions. Urediniospores collected from field-infected soybean leaves were stored in 1.5-ml microcentrifuge tubes under different conditions. Spore samples were removed every other day from experimental conditions, and water was added to allow spore germination under optimum conditions. Germinating spores were counted under the light microscope. The germination rate of P. pachyrhizi urediniospores declined by 50% within 2 days at 0C, and further declined to 8% after 20 days at 0C. Under simulated Louisiana winter conditions (12C 14-h day and 1C 10-h night with 75% relative humidity), the germination rate declined by 50% after 5 days and gradually decreased to 12.5% after 20 days. This study indicates that soybean rust spores may survive the typical winter conditions encountered in Louisiana and become the source of inoculum for new infections in the next growing season.

                                        Back to Poster Presentations