Photo courtesy of Clive Levy, Commercial Farmer’s Union of Zimbabwe

1. Soybean Rust: Management Options Kent L. Smith, Ph.D. USDA, Office of Pest Management Policy May 11, 2004 Photo courtesy of Clive Levy, Commercial Farmer’s Union of Zimbabwe

2. Impact of Soybean RustYield Impact • Yield losses in soybeans – reported to be 10 to 50% of area yield where established, up to 90% or greater in selected fields • Minor crop impact – soybean rust pathogen has wide host range on leguminous crops – lima beans, black-eyed peas, kidney beans, green beans, etc.

3. Impact of Soybean Rust Economic Impact • Economic impact on U.S. Economy – estimated by USDA/ERS in April 2004: www.ers.usda.gov • Yield Impacts from 0.9% to -9.5% • Benefits of higher prices for soybeans and corn • Net losses of $0.2 to 2.0 billion

4. THE DISEASE TRIANGLE Pathogen Environment Amount of Disease Host Courtesy of Reid Frederick, USDA/ARS

5. Research on Disease Management of Soybean Rust • Host resistance – screening of soybeans by ARS in U.S. containment facilities • Fungicide Application Methods – ARS and States (SD,NE,IL,AR,MS,LA) • Comparative fungicide efficacy – trials directed by ARS in South America and Africa • Disease forecasting – APHIS & Iowa State University

6. Plant Pathogen Containment BSL-3 Facility, Bldg. 374 Courtesy of Reid Frederick, USDA/ARS

7. Courtesy of Reid Frederick, USDA/ARS

8. Courtesy of Reid Frederick, USDA/ARS

9. Screening of Soybean Germplasm for SBR Resistance 16,000 soybean accessions challenged in greenhouse 200 tested under field conditions < 100 exhibit some resistance Conventional Breeding for Resistance 4 to 10 years

10. Fungicidal Control of Soybean Rust in Zimbabwe Strip not protected by fungicide Photo courtesy of USDA/APHIS

11. No Fungicides With Fungicides Photo courtesy of Clive Levy, Commercial Farmer’s Union of Zimbabwe

12. Soybean Rust Management Suggestions • Fungicide treatments – 0-4/season • Timing of fungicides – during reproductive growth or earlier based on sentinel crops, local reports, and weather • Economic threshold – NONE • Sentinel Crops – kudzu, soybeans or various other leguminous plants • Cultural control – row spacing, early planting • Weather based advisory

13. Cost of Fungicide Treatment of Soybeans • ASA estimate ~ $15/acre/treatment Survey results by USDA: • Fungicide cost -- $6-32/acre (average ~ $10) • Application cost: • By ground -- $2-10/acre (average ~ $4.50) • By air -- $4-12/acre (average ~ $6.50)

14. Fungicides Registered in U.S. for Soybean Rust on Soybeans • Azoxystrobin (Quadris) • Chlorothalonil (Bravo and Echo)

15. Fungicides Registered in U.S. for Rust On Other Legumes (lima beans, green beans, kidney beans, cowpeas, pigeon peas, and others) • Azoxystrobin (Quadris) • Chlorothalonil (Bravo and Echo) • Pyraclostrobin (Headline) • Maneb (Manex) on dry beans • Myclobutanil (Laredo, Rally) on green beans

16. Other foliar fungicides registered in U.S. on legumes(some for organic use?) carbonic acid, monopotassium salt (Armicarb) – soybeans, lima beans, green beans, dry beans cinnamaldehyde (Cinnacure) – soybeans (for rust) coppers – soybeans, lima beans, dry beans, green beans harpin (Messenger) – soybeans, dry beans hydrogen peroxide (Rezistox) – dry beans (for rust) neem oil – soybeans (for rust)

17. Other foliar fungicides - Continued potassium phosphate, monobasic (Nutrol) – soybeans, lima beans, dry beans potassium salts of fatty acids (M-pede) – soybeans sulfur – soybeans; lima beans, dry beans, green beans, and cowpeas (for rust) thiabendazole (Mertect) – soybeans thiophanate-methyl (Topsin M) – soybeans ziram – lima beans

18. Fungicides Requested to Control Soybean Rust on Soybeans under Quarantine Exemption (Section 18)by South Dakota and Minnesota • Propiconazole (Tilt, Propimax, Bumper) – Granted 4/23/04 • Tebuconazole (Folicur) • Myclobutanil (Laredo) – Granted 3/25/04 • Trifloxystrobin + propiconazole (Stratego) • Tetraconazole (Eminent) • Pyraclostrobin (Headline) • Boscalid + pyraclostrobin (Pristine)

19. Limits of MN & SD Quarantine Exemptions Treat no more that 50% soybean acreage (EPA will consider 100% usage) Maximum of 2 applications total (EPA will consider 3 applications total) Rationale needed for greater usage longer season varieties environment more conducive to disease closer to overwintering sites

20. Requests for “me too” Quarantine Exemptions for soybean rust Apply for all 7 fungicides requested by SD & MN Follow EPA instructions for citing MN & SD quarantine exemption

21. Fungicide Resistance Action Committee (FRAC)www.frac.info For Strobilurins (azoxystrobin, pyraclostrobin, trifloxystrobin) used alone in only 1/3 of applications used in mixes in only 1/2 of applications For Triazoles (propiconazole, tebuconazole, myclobutanil, tetraconazole) alternate with other chemistries if possible

22. Web Site on Soybean Rusthttp://www.ipmcenters.org/NewsAlerts/soybeanrustFor more information on soybean rust, please contact: Kent SmithTeung Chin (plant pathology & registrations)(fungicide toxicity & Section 18s) 202-720-3186 301-734-8943 ksmith@ars.usda.gov Teung.F.Chin@usda.gov Ted Rogers (organic soybeans & legumes) 202-720-3846 Trogers@ars.usda.gov