US Soybean Rust DetectionUS Soybean Rust Detectionand Aerobiological Modelingand Aerobiological Modeling

November, 2004November, 2004

Dan Borchert, Glenn Fowler and Roger Magarey (USDA-APHIS-PPQ-CPHST-PERAL)Dan Borchert, Glenn Fowler and Roger Magarey (USDA-APHIS-PPQ-CPHST-PERAL)Daryl Jewett (USDA-APHIS)Daryl Jewett (USDA-APHIS)

Annalisa Ariatti (UIUC)Annalisa Ariatti (UIUC)Scott Isard (PSU)Scott Isard (PSU)

Manuel Colunga and Stewart Gage (MSU)Manuel Colunga and Stewart Gage (MSU)Glenn Hartman and Monte Miles (ARS and NSRL)Glenn Hartman and Monte Miles (ARS and NSRL)

Thomas Keever and Charlie Main (NCSU)Thomas Keever and Charlie Main (NCSU)Jeff Grimm, Aaron Hunt and Joe Russo (ZedX, Inc.)Jeff Grimm, Aaron Hunt and Joe Russo (ZedX, Inc.)

MethodsMethods

The Integrated Aerobiology Modeling The Integrated Aerobiology Modeling System (IAMS) was used to simulate daily System (IAMS) was used to simulate daily soybean rust spore movement (Isard et al., soybean rust spore movement (Isard et al., 2004) 2004)

Viable spore deposition (logarithmic) is Viable spore deposition (logarithmic) is modeled from September 15 to 19, 2004 in modeled from September 15 to 19, 2004 in association with Hurricane Ivanassociation with Hurricane Ivan

Uncertainty is associated with spore source Uncertainty is associated with spore source strength and the absolute quantity of sporesstrength and the absolute quantity of spores

Aerobiological Model AssumptionsAerobiological Model Assumptions Source area (17,000 sq Km) was from soybean production areas Source area (17,000 sq Km) was from soybean production areas

in northwestern South Americain northwestern South America Spores were released near midday from August 30 to Spores were released near midday from August 30 to

September 9, 2004September 9, 2004 25% of the source area was infested with soybean rust25% of the source area was infested with soybean rust 6 million spores were released per day per heavily infected 6 million spores were released per day per heavily infected

soybean plant with a planting density of 500,000 plants/hasoybean plant with a planting density of 500,000 plants/ha 33% of these spores were released near midday33% of these spores were released near midday 15% of the released spores were able to escape from the 15% of the released spores were able to escape from the

canopycanopy Mortality due to UVB radiation exposure in the air was Mortality due to UVB radiation exposure in the air was

proportional to cloud-adjusted surface total incoming solar proportional to cloud-adjusted surface total incoming solar radiationradiation

Wet deposition of viable spores was proportional to the observed Wet deposition of viable spores was proportional to the observed surface precipitation totalsurface precipitation total

Computational ProcedureComputational Procedure

Model domain was divided into 14 kmModel domain was divided into 14 km2 2 grid cellsgrid cells NWS reanalysis 2 dataset was used to calculate the most NWS reanalysis 2 dataset was used to calculate the most

likely downwind direction for 6 pressure levels (altitudes) at likely downwind direction for 6 pressure levels (altitudes) at 6 hr intervals6 hr intervals

Spores were moved up or down among pressure levels in Spores were moved up or down among pressure levels in accordance to the vertical component of the windaccordance to the vertical component of the wind

Mortality due to UV exposure and rainout of spores was Mortality due to UV exposure and rainout of spores was calculated for each time step after downwind movementcalculated for each time step after downwind movement

Deposition of spores was accumulated for all days in the Deposition of spores was accumulated for all days in the calculations and is given as the number of spores per calculations and is given as the number of spores per hectarehectare

US Planted Soybean Acreage per US Planted Soybean Acreage per CountyCounty

September 15, 2004September 15, 2004

September 16, 2004September 16, 2004

September 17, 2004September 17, 2004

September 18, 2004September 18, 2004

September 19, 2004September 19, 2004

Planted Soybean Acreage per Planted Soybean Acreage per CountyCounty

Kudzu Area per CountyKudzu Area per County

Soybean Rust Spore DepositionSoybean Rust Spore Deposition

Soybean Rust Spore Deposition and Soybean Rust Spore Deposition and Planted Soybean Acreage per CountyPlanted Soybean Acreage per County

Soybean Rust Spore Deposition and Soybean Rust Spore Deposition and Kudzu Area per CountyKudzu Area per County

Data SourcesData Sources

KudzuKudzu: Raw data Daryl Jewett (USDA-APHIS) : Raw data Daryl Jewett (USDA-APHIS) unpublished data. Kudzu map Annalisa Ariatti and unpublished data. Kudzu map Annalisa Ariatti and Scott Isard (PSU/UIUC).Scott Isard (PSU/UIUC).

Soybean Acreage: NASS, 2003; National Land Soybean Acreage: NASS, 2003; National Land Cover Data, 1992; Colunga, 2004Cover Data, 1992; Colunga, 2004

Spore Deposition: Isard, S., Main, C., Keever, T., Spore Deposition: Isard, S., Main, C., Keever, T., Magarey, R., Redlin, S, and Russo, J. (2004) Magarey, R., Redlin, S, and Russo, J. (2004) Weather-Based Assessment of Soybean Rust Weather-Based Assessment of Soybean Rust Threat to North America. Final Report to APHIS Threat to North America. Final Report to APHIS http://www.aphis.usda.gov/ppq/ep/soybean_rust/http://www.aphis.usda.gov/ppq/ep/soybean_rust/