My research
is to identify and define the role(s) of fungal pathogens infecting
soybeans. Host resistance is a major emphasis for Phytophthora root
rot, Sudden Death Syndrome, and Seedborne Diseases. Also, in order to
evaluate soybean germplasm and breeding lines for disease resistance,
an extensive culture collection of soybean pathogens is maintained and
utilized to identify and describe mycological and physiological characteristics
of the biotypes associated with each disease.
Research
on the soybean disease SDS or "Sudden Death Syndrome" has
identified Indiana isolates of Fusarium solani capable of causing
both root rot and leaf symptoms. Highly virulent isolates obtained from
soybeans with SDS symptoms produced the rarely observed Nectria
sexual stage in culture. This Nectria/Fusarium association has
not been identified previously with soybean isolates of the fungus.
Although ascospores were not required for hypocotyl infection, virulence
of the F. solani isolates that produced Nectria in culture
was higher than that of other isolates. Identification and production
of Nectria ascoma stage in culture provides an excellent opportunity
to initiate screening of soybean germplasm for SDS resistance.
The majority
of fungal pathogens causing yield losses occur regularly in most soybean
fields each year. It is also evident that several fungi infect plants
long before disease symptoms are recognized. The early plant infections
not only serve as an important inoculum source for late season disease
development, but have an impact on the performance and yield potential
of the soybean host. Latent development of these fungi can be triggered
by factors such as host resistance and environmental conditions. The
USDA-Purdue Integrated Pest management System has demonstrated that
late season disease development and seed health are influenced by crop
rotation, tillage operation, and weed control. This work demonstrated
that latent infections by Diaporthe, Phomopsis, Colletotrichum,
Septoria, Cercospora and Macrophomina represent
a complex of interactions that reduces seed yield and quality.
Faculty