An assessment of the risk of aerial transport of rust pathogens to the Western Hemisphere and within North America Scott A. Isard Departments of Plant Pathology and Meteorology Pennsylvania State University University Park, PA USA 16802 and Joseph M. Russo ZedX Inc. Bellefonte, PA 16853 2011 BGRI Technical Workshop, St. Paul, MN: 14 June 2011
Question How frequently are there opportunities for rust pathogens to be transported: 1. From locations in the Eastern Hemisphere to the Western Hemisphere 2. From locations in subtropical regions to the continental interior of North America
Aerobiota Transport Process Model Horizontal Transport Takeoff and Ascent Earth s atmosphere Descent and Landing Preconditioning Earth s surface Impact SOURCE AREA DESTINATION AREA opportunities consideration of processes that occur in the atmosphere
Integrated Aerobiology Modeling System (IAMS) Synoptic Scale Airflows Govern Transport Direction and Speed Turbulent Diffusion and Wind Shear Govern Dilution Turbulent Transport and Dilution in the Atmosphere Survival of Spores while Airborne Ultraviolet Radiation Temperature and Relative Humidity Vertical Distribution of Spores in Canopy Canopy Density & Structure Wind & Turbulence Time of Spore Release Escape of Spores from Canopy IAMS Modules Deposition of Spores into a Crop Dry Deposition Due to Wind and Turbulence Wet Deposition Due to Washout by Precipitation Plant Growth Stage of Disease Weather Spore Production Colonization of Crop Temperature & Leaf Wetness Crop Growth Stage Isard et al. 2005 BioScience 55: 851-862.
Potential Destination Regions Used in Analysis Alaska Aleutian Islands British Columbia Washington & Oregon California Gulf Coast Hawaii Mexico & Central America Eastern Canada U.S. Northeast Coast U.S. Southeast Coast Florida Greater Antilles Lesser Antilles Northeastern South America Northern Chile Southeastern South America Central Chile Southern Chile
Potential Source Regions Used in Analysis Alaska Washington & Oregon British Columbia Eastern Canada United Kingdom Northern China Hawaii California Gulf Coast Mexico & Central America Spain/Morocco U.S. Southeast Coast Florida Greater Antilles Lesser Antilles Sierra Leone Northeastern South America Nigeria Cameroon Southern China Philippine Islands Northern Chile Central Chile Southeastern South America Angola South Africa Eastern Australia Southern Chile
Parameters and Input Data for IAMS Simulations - Grid spatial resolution was 0.083 degrees (~ 14 km), - Vertical resolution was defined by the standard pressure levels (1000, 950, 900, 850, 800, 700, 600, 500 hpa) - One hr time step. - National Center for Environmental Prediction Department of Energy Reanalysis 2 data set for the 1998-2007 period - Each simulation was initiated for 1 January 1998 with the daily spore production held constant for the duration of the 10-yr run. - Nine grid cells (equivalent to about 125,000 ha at the Equator), distributed throughout a source area, were assumed to have a healthy crop and rust infection severity of 50%. - Parameters for the spore release and escape, dispersion, mortality and deposition modules were those used in a previous soybean rust study (Isard et al. 2007)
Frequency of Days with Deposition of Viable Rust Spores in Western Hemisphere as Simulated by IAMS for 1998-2007 Averaged for for September for November December February October January August March June April Year May July 0.1/mo 0.4/mo 0.9/mo 0.6/mo 1.3/mo 0.2/mo 0.3/mo 2.6/mo 1.2/mo 5.4/mo 1.3/mo 1.1/mo 9.5/mo 5.0/mo 2.2/mo 11.6/mo 9.6/mo 11.7/mo 14.4/mo 6.1/mo 11.0/mo 8.7/mo 5.3/mo 7.0/mo 10.1/mo 9.3/mo 29.9/mo 27.2/mo 22.3/mo 13.0/mo 5.9/mo 30.8/mo 12.6/mo 18.4/mo 1.1/mo 0.7/mo 9.4/mo 28.1/mo 16.6/mo 11.5/mo 9.5/mo 2.2/mo 0.1/mo 12.8/mo 1.6/mo 2.7/mo 3.4/mo 4.1/mo 1.7/mo 0.4/mo 1.3/mo 0.9/mo 0.7/mo 2.5/mo 1.1/mo 2.2/mo 0.6/mo 6.5/mo 0.4/mo 1.2/mo 1.5/mo 2.0/mo 4.1/mo 1.0/mo 0.6/mo 3.5/mo 3.9/mo 1.8/mo 0.5/mo 1.5/mo 3.6/mo 0.8/mo 0.1/mo 0.4/mo 9.4/mo 13.7/mo 16.7/mo 18.0/mo 6.3/mo 7.6/mo 10.4/mo 4.7/mo 2.1/mo 0.8/mo 3.3/mo 4.6/mo 8.1/mo 0.3/mo 0.7/mo 0.1/mo 0.4/mo 0.2/mo
Frequency of Days with Deposition of Viable Rust Spores from Eastern Hemisphere Source Regions in U.S. & Canadian Destination Regions 0.4/mo 0.1/mo 0.3/mo 0.3/mo 0.4/mo 0.2/mo 0.1/mo 0.1/mo 0.1/mo Averaged for All Months in Year 0.1/mo 0.1/mo 0.2/mo Averaged for entire year Simulated by IAMS for 1998-2007
Frequency of Days with Deposition of Viable Rust Spores from African Source Regions in the Caribbean Islands Averaged for entire year 4.1/mo 2.4/mo 4.7/mo 0.1/mo 0.4/mo 0.03/mo 0.01/mo 0.01/mo Simulated by IAMS for 1998-2007
Frequency of Days with Deposition of Viable Rust Spores from African Source Regions in Eastern South America Trade Winds > 90% of days 70-90% of days 70-50% of days 7.9/mo January 15.9/mo 3.2/mo 0.7/mo July 0.4/mo 7.2/mo 5.5/mo 0.4/mo 0.03/mo > 90% of days 70-90% of days 70-50% of days Averaged for entire year 0.03/mo 2.1/mo Simulated by IAMS for 1998-2007
IAMS Model Output 20 21 22 23 24 May 1998 11 12 13 14 15 January 1998
Summary of Insights from IAMS Simulations The frequency of trans-oceanic transport and deposition of viable rust spores in the Western Hemisphere : Africa, tropics low Europe, north of Pyrenees/Alps low Eastern Asia/Australia low Africa, poleward of the tropics high relatively short distance persistent trade winds Regions in the Western Hemisphere that are influenced by the ITCZ have the highest likelihood of receiving viable rust spores from the Eastern Hemisphere high frequency & high intensity deposition events Risk of direct aerial transport of viable rust spores to U.S. and Canada - low
Question How frequently are there opportunities for rust pathogens to be transported: 1. From locations in the Eastern Hemisphere to the Western Hemisphere 2. From locations in subtropical regions to the continental interior of North America
30 April 2010 Wind Speed (m/s) < 5 5-10 >10 The wind speed and directions are averaged for the air layer between the ground and the height at which air pressure decreases 30 hpa (typically 200 m near mid-day).
Frequency of strong low-level airflows: South Texas and Delta Regions to designated continental interior regions 1 2 Wheat Acres 0.19 0.40 3 0.23 0.19 4 0.33 D 5 0.25 Destination Regions 1. South Dakota/North Dakota/southern Manitoba/southeastern Saskatchewan 2. Minnesota/Iowa/Wisconsin/ southwestern Ontario 3. Kansas/Nebraska T Source Regions 4. Missouri 5. Illinois/Indiana T. South Texas USDA, National Agricultural Statistics Service D. Mississippi River Delta Region April 2006-2010
Frequency of strong low-level airflows: South Texas and Delta Regions to designated continental interior regions 1 2 Wheat Acres 0.11 0.28 3 0.13 0.10 4 0.19 D 5 0.18 Destination Regions 1. South Dakota/North Dakota/southern Manitoba/southeastern Saskatchewan 2. Minnesota/Iowa/Wisconsin/ southwestern Ontario 3. Kansas/Nebraska T Source Regions 4. Missouri 5. Illinois/Indiana T. South Texas USDA, National Agricultural Statistics Service D. Mississippi River Delta Region May 2006-2010
Frequency of strong low-level airflows: South Texas and Delta Regions to designated continental interior regions 1 2 Wheat Acres 0.10 0.31 3 0.18 0.06 4 0.11 D 5 0.10 Destination Regions 1. South Dakota/North Dakota/southern Manitoba/southeastern Saskatchewan 2. Minnesota/Iowa/Wisconsin/ southwestern Ontario 3. Kansas/Nebraska T Source Regions 4. Missouri 5. Illinois/Indiana T. South Texas USDA, National Agricultural Statistics Service D. Mississippi River Delta Region June 2006-2010
Frequency of strong low-level airflows: South Texas and Delta Regions to designated continental interior regions 1 2 Wheat Acres 0.04 0.10 3 0.07 0.01 4 0.04 D 5 0.03 Destination Regions 1. South Dakota/North Dakota/southern Manitoba/southeastern Saskatchewan 2. Minnesota/Iowa/Wisconsin/ southwestern Ontario 3. Kansas/Nebraska T Source Regions 4. Missouri 5. Illinois/Indiana T. South Texas USDA, National Agricultural Statistics Service D. Mississippi River Delta Region July 2006-2010
Frequency of strong low-level airflows: South Texas and Delta Regions to designated continental interior regions 1 2 Wheat Acres 0.01 0.12 3 0.05 0.01 4 0.03 D 5 0.02 Destination Regions 1. South Dakota/North Dakota/southern Manitoba/southeastern Saskatchewan 2. Minnesota/Iowa/Wisconsin/ southwestern Ontario 3. Kansas/Nebraska T Source Regions 4. Missouri 5. Illinois/Indiana T. South Texas USDA, National Agricultural Statistics Service D. Mississippi River Delta Region August 2006-2010
Frequency of strong low-level airflows: South Texas and Delta Regions to designated continental interior regions 1 2 Wheat Acres 0.04 0.04 3 0.04 0.03 4 0.06 D 5 0.06 Destination Regions 1. South Dakota/North Dakota/southern Manitoba/southeastern Saskatchewan 2. Minnesota/Iowa/Wisconsin/ southwestern Ontario 3. Kansas/Nebraska T Source Regions 4. Missouri 5. Illinois/Indiana T. South Texas USDA, National Agricultural Statistics Service D. Mississippi River Delta Region September 2006-2010
Summary of Insights from Airstream Analysis Strong low-level advection of air northward from the subtropics is prevalent in North America east of the Rocky Mountains from early April to mid June providing opportunities for long-distance transport of rust pathogens into the continental interior. After mid-june, the number of days with strong low-level advection of air from south to north across these regions decreases dramatically.
Winter Wheat 2010 Harvested Acres by U.S. County Soybean 2010 Harvested Acres by U.S. County Winter Wheat Crop Calendar for Texas Soybean Crop Calendar for Delta Region Head Plant Plant Harvest J F M A M J J A S O N D Harvest J F M A M J J A S O N D Risk of long-distance aerial spread of soybean rust less than wheat rust during the periods when they could potentially cause crop losses in major North American production regions