Producing high soybean yields begins with establishing an even stand of vigorous plants. Producers have often overplanted to make up for stand losses due to poor seed quality, seedling diseases, and adverse environmental conditions. As seed prices rise, producers plant fewer seed per acre and depend on a higher percentage of their seed emerging than ever before. Seedling diseases, poor seed quality, and the environment often interact and lead reduced stand establishment, plant health and vigor, with these factors often interacting to reduce emergence. Unfortunately, there is much we do not know about these factors. In 2005, seedling diseases in the U.S. were estimated to result in soybean yield losses of 829 thousand tones.

1. Identify fungi responsible for causing seedling blights of soybean
2. Develop high throughput diagnostic tools for identification of fungal seedling pathogens
3. Characterize the biology of seedling pathogens and develop assays for inoculation
4. Identify the impact of environmental conditions on seedling pathogens and epidemiology

The completion of the proposed objectives will improve our understanding of the different pathogenic species that cause seedling diseases and root rot of soybean, and the relative importance of these species in the different soybean growing regions. This research will also provide insight regarding the aggressiveness of these pathogens under different environmental conditions. A collection of characterized isolates of pathogens that cause seedling diseases will be cataloged. This work will also validate use of culture-independent techniques to generate profiles of pathogens inhabiting soils and soybean seedlings from fields with high incidence of seedling diseases. Field conditions (moisture, temperature and chemical properties) that favor seedling diseases will also be identified.

1. Identification of the most common pathogenic fungi in diseased soybean seedling roots
2. Establishment of a collection of isolates of pathogenic fungi from soybean seedlings
3. Improve the understanding of the variation in aggressiveness within and among species of Pythium and fungi
4. Development of universal or standardized methods to produce inoculum and inoculate seedling for epidemiological studies and for future soybean germplasm evaluations
5. Identification of environmental factors favoring infection and disease development for fungal and oomycete seedling pathogens
6. Characterize fungicide sensitivity of fungal and oomycete seedling pathogens