Organizing Committee


Poster Presentations


Poster Presentations


Ultraviolet radiation effects on soybean rust urediniospores

Presenter: Hans Schmitz(1)

Other authors and affiliations: Wayne M. Jurick(2), Richard H. Grant(1), Carrie L. Harmon(2), Philip F. Harmon(2). (1)Purdue University, Agronomy, West Lafayette, IN 47907, U.S.A.; (2)University of Florida, Plant Pathology, Gainesville, FL 32611, U.S.A.

The attempt to explain spore extinction via ultraviolet-B (UV-B) irradiance during atmospheric transport remains important, especially to characterize the potential of long-range transport for Phakopsora pachyrhizi spores. In this study, solar radiation and temperature effects on P. pachyrhizi urediniospores were surveyed and an exposure model developed that presents the spore as a three-dimensional, ellipsoidal object rather than a flat particle. Using natural sunlight as the radiation source, filters were placed over some spores that controlled the wavelengths of spore irradiance. Temperature was also studied using various shaded controls. Reduction in spore viability as a result of increased UV-B wavelength radiation exposure was evident with an LD90 on the spore extinction model of 780 J/m2/nm. Over Florida, approximately 16 h of clear day exposure would result in 90% extinction. Reduction in viability was not observed on spores exposed to non-UV-B wavebands. No dependence on temperature for the range of temperatures studied was observed. Analysis of a transport episode shows differences between exposure and extinction models.

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