Organizing Committee


Poster Presentations

Poster Presentations


The wet deposition of soybean rust urediniospores

Presenter: N. Dufault

All authors and affiliations: N. DUFAULT (1), S. A. Isard (1), J. Marois (2), D. Wright (2). (1) Penn State University, University Park, PA; (2) North Florida Research and Education Center, University of Florida, Quincy, FL

Rainfall can deposit Phakopsora pachyrhizi urediniospores into soybean canopies at depths favorable to urediniospore germination and infection. In this study, a rainfall simulator was used examine the effects of rainfall intensity, plant height, and row spacing on the vertical distribution of rainfall-deposited urediniospores within a soybean canopy. Urediniospore-injected simulated rainfalls of 45 or 85 mm/h were conducted at 35- and 75-cm plant heights within field sections of 19- and 76-cm row spacing in Quincy, Florida. A detached leaflet bioassay was used to sample urediniospore wet deposition at three collection levels within the soybean canopy. Both rainfall intensity and plant height had significant (P < 0.05) effects on the proportion of uredinia per cm2 recorded at each collection level. In general, deposition into the middle and lower soybean canopy sections was favored by high rainfall intensity events at low plant canopy heights. Row spacing had no significant (P > 0.10) effect on the vertical distribution of urediniospores within a soybean canopy. Our results suggest that as much as 3% of the viable urediniospores washed from the atmosphere are deposited and subsequently produce uredinia on leaves in the middle and lower sections of soybean canopies.

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