The observations gained from disease monitoring have greatly
improved our understanding of SBR and ability to manage the
disease. For example, monitoring efforts have helped identify and
quantify the role of additional hosts in rust development. Kudzu,
the primary overwintering host of P. pachyrhizi in the southern
United States, is genetically diverse. Biotypes exist that resist disease
development, which influences the potential for inoculum
development and predicted disease dispersal (4,34,70). Additional
information on the inoculum load contributed from other known
hosts of SBR is important to continued disease prediction and
modeling efforts. Research on the influence of environmental variables
upon disease development also has aided modeling efforts.
Young et al. (84) reported that sunlight reduces survival of spores
of P. pachyrhizi in the upper soybean canopy, whereas spore viability
and disease severity increased in the shaded, lower canopy.
These findings suggest that spore survival within a canopy could
impact disease development and models for disease spread