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Management Options for Soybean Rust; Resistance and Fungicides.

Management Options for Soybean Rust; Resistance and Fungicides. Monte R. Miles USDA-Agricultural Research Service Department of Crop Sciences National Soybean Research Center University of Illinois, Urbana, IL www.soydiseases.uiuc.edu. PHAKOSPORA PACHYRHIZI. OBLIGATE PARASITE

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Management Options for Soybean Rust; Resistance and Fungicides.

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  1. Management Options for Soybean Rust; Resistance and Fungicides. Monte R. Miles USDA-Agricultural Research Service Department of Crop Sciences National Soybean Research Center University of Illinois, Urbana, IL www.soydiseases.uiuc.edu

  2. PHAKOSPORA PACHYRHIZI OBLIGATE PARASITE UREDINIOSPORES NO ALTERNATE HOST IS KNOWN DIRECT PENETRATION INFECTION CYCLES IN 5 TO 7 DAYS C. STONE

  3. São Desidério, Roda Velha, BA, March 8, 2003 J. T. Yorinori

  4. Photo: M. Assunção (Embrapa Soja/CTPA)/José Nunes Jr (CTPA); Campo Alegre, GO

  5. Management of Soybean Rust • Short-term solutions • Fungicides • Long-term solutions • Host resistance • Specific resistance • Partial resistance • Yield stability • Combination of fungicides and resistance

  6. RESISTANCE TO SOYBEAN RUST • SPECIFIC OR SINGLE GENE RESISTANCE • PARTIAL OR RATE REDUCING RESISTANCE • YIELD STABILITY OR TOLERANCE

  7. Initial Screening of Germplasm • Initial studies • 1961 ≈ 2,800 accessions screened in Taiwan (U.S collection) • 1970 ≈ 4,000 accessions screened in India (U.S. collection) • 1975 ≈ 1,675 accessions (MG V-X) screened in Taiwan (AVRDC) • From these studies, sources of resistance were found and the inheritance of resistance was characterized

  8. Specific Resistance • Hartwig and Bromfield 1983 • Showed that three soybean lines each carried a single dominant gene conferring specific resistance • Each gene was found to be at a different locus • Hartwig 1986 • Identified a fourth major gene for resistance

  9. Host Response • Immune reaction - hypersensitive reaction with rapid cell death near the infection site without sporulation - rarely seen • Resistant - red-brown (RB) reaction, lesions may or may not develop into sporulating pustules • Susceptible - Tan lesions that develop into sporulating pustules C. STONE

  10. GENE ACCESSION FOUND LOST • Rpp1 PI200492 1960-62 1966 • Rpp2 PI230970 1972-74 1978 • Rpp3 PI462312 1973-75 1977 • Rpp4 PI459025 1980-83 2004

  11. Virulence diversity of P.pachyrhizi • In Australia, 8 isolates were separated into 6 races using wild Glycine species as the differentials. • Native populations of wild Glycine spp show differential responses. • In China, nine isolates that had a susceptible reaction on soybean were separated into 6 phenotypes using asparagus bean, kidney bean and short podded yam bean.

  12. Virulence diversity of P.pachyrhizi • In a screen of 42 single spore isolates from Taiwan, 9 races were identified using 11 G. max resistant sources. • No resistant source was effective against all isolates

  13. VIRULENCE IS DIVERSE AND COMPLEX PHYSIOLOGICAL SPECIALIZATION HAS BEEN SEEN ON MANY LEGUMES, THE WILD GLYCINE RELATIVES OF SOYBEAN, AS WELL AS ON SOYBEAN ACCESSIONS

  14. PARTIAL RESISTANCE • REDUCES THE RATE OF AN EPIDEMIC BY SLOWING DOWN PATHOGEN • USUALLY NOT A SINGLE GENE • USUALLY NOT RACE SPECIFIC • NOT A +/- TYPE OF EVALUATION • EVALUATED OVER TIME • GROWTH STAGE IMPORTANT

  15. HOW DOES PARTIAL RESISTANCE OR“SLOW RUSTING” WORK? • REDUCES INFECTION FREQUENCY- FEWER LESIONS • INCREASES LATENT PERIOD - PATHOGEN NEEDS A LONGER TIME TO PRODUCE UREDINIA AND SPORES • REDUCES SPORE PRODUCTION- FEWER UREDINIA AND FEWER SPORES / UREDINIA DIFFICULT TRAITS TO WORK WITH

  16. EXAMPLE OF PARTIAL RESISTANCE - PUSTULE COUNTS G. L HARTMAN

  17. HOW WILL PARTIAL OR “SLOW RUSTING” RESISTANCE BE EVALUATED ? • DISEASE SEVERITY OVER TIME • ESTIMATED PER PLOT • AREA AFFECTED, DEFOLIATION, GREEN LEAF AREA • PATHOGEN REPRODUCTION OVER TIME • PUSTULE COUNTS, SPORE PRODUCTION, LATENT PERIOD • GROWTH STAGE IS IMPORTANT • RELATIVE LIFE TIME (0-100%)

  18. Yield Stability • Relative yielding ability of soybeans under stress from rust • Compare yields between fungicide-protected plots and non-protected plots • Yield stability assessment - Needs to be done with adapted germplasm

  19. 100 80 60 40 20 0 1 2 3 4 5 6 7 8 9 10 11 12 Yield Loss Differences LOW YIELD STABILITY Yield loss (%) MOST YIELD STABILITY Soybean entry

  20. GOIAS Photo: Mauricio Assunção – Embrapa Soja/CTPA; Campo Alegre, GO

  21. MATO GROSSO Primavera do Leste, MT: 21.02.03

  22. Fungicides will be the primary tool to control Asian soybean rust in the near future.

  23. FUNGICIDES REGISTERED FOR USE ON SOYBEAN AND LABLED FOR CONTROL OF SOYBEAN RUST CHLOROTHALONIL • BRAVO (SYNGENTA) • ECHO ( SIPCAM AGRO) AZOXYSTROBIN • QUADRIS (SYNGENTA)

  24. FUNGICIDES ON THE SECTION 18 EMERGENCY EXEMPTION REQUEST • MYCOBUTANIL * • PROPICONAZOLE * • PYRACLOSTROBIN • PYRACLOSTROBIN + BOSCALID ** • TEBUCONAZOLE • TETRACONAZOLE • TRIFLOXYSTROBIN + PROPOCONIZOLE * APPROVED BY EPA, ** BOSCALID IS REGISTERED

  25. CURATIVE ABSORBED TRANSLOCATES KILLS FUNGAL TISSUE USE AFTER INFECTION TRIAZOLES PROTECTANT +/-ABSORBED +/-TRANSLOCATE PREVENTS INFECTION OR SPORULATION USE BEFORE INFECTION STROBALURINS AND CHLOROTHALONILS ALL FUNGICIDES ARE NOT THE SAME

  26. EVALUATE FUNGICIDES THAT ARE LABLED OR ON THE SECTION 18 REQUEST COMPARISON OF 2 AND 3 APPLICATIONS WITH FIRST APPLICATION SOON AFTER FLOWERING FUNGICIDE EFFICACY TRIALS IN SOUTHERN AFRICA AND SOUTH AMERICA M. Miles

  27. RECCOMENDATIONS FOR CHEMICAL CONTROL • BRAZIL AND SOUTHERN AFRICA ARE THE SOURCES OF INFORMATION • FORMULATIONS WE WILL HAVE WILL DIFFER FROM BRAZIL AND AFRICA • NOT ALL FUNGICIDES WILL BE AVALIABLE IN THE U.S.

  28. RECOMMENDATIONS FOR CHEMICAL CONTROL • FIRST APPLICATION NEEDS TO BE AT OR SOON AFTER FIRST FLOWER - IN ZIMBABWE THIS WAS 50 DAYS AFTER PLANTING. • 2 OR 3 APPLICATIONS ARE NEEDED • 14 - 20 DAYS BETWEEN APPLICATIONS • THE FUNGICIDE NEEDS TO PENETRATE THE CANOPY

  29. ADDITIONAL RECCOMENDATIONS- • STROBALURIN FUNGICIDES NEED TO BE USED AS A PROTECTANT, ONCE RUST IS AT 5-10% THEY DO NOT ALWAYS PROTECT YIELD • STROBALURINS ARE SINGLE SITE MODE OF ACTION - USED ONLY ONCE PER SEASON • MANY TRIAZOLES MAY NOT HAVE THE RESIDUAL NEEDED FOR 20+ DAY INTERVALS • ENVIRONMENT WILL HAVE AN EFFECT • MIXES OF TRIAZOLES AND STROBALURINS • ROTATE THE FUNGICIDES

  30. OK, SO WHAT DO I USE?THERE ARE MANY QUESTIONS THAT NEED TO BE AWNSERED FIRST THE SECTION 18 EMERGENCY EXEMPTION REQUESTS HAVE 3 OR 4 SENARIOS WITH RECCOMENDATIONS THAT DEPEND ON PRESENCE OR PREDICTION OF RUST • IS THE RUST PRESENT? HOW SEVERE? • DO YOU NEED CURATIVE FUNGICIDE OR WILL A PROTECTANT FUNGICIDE WORK? • ECONOMICS AND TIME OF SEASON? • WHAT IS THE PRE HARVEST INTERVAL OF THE FUNGICIDE YOU WANT TO USE?

  31. HOWCAN WE PENETRATE THE CANOPY? • AERIAL AND GROUND • NORMAL AND HIGH VOLUME • TYPE OF NOZZLE FOR GROUND APPLICATION M. MILES, 2003

  32. FUNGICIDES ARE USED IN SOYBEAN PRODUCTION IN THE MID AND DEEP SOUTH • RESULTS ARE MIXED. • QUADRIS • QUADRIS + WARRIOR • NOT ALWAYS ASSOCIATED WITH PEST CONTROL. D. HERSHMAN, U OF KY.

  33. WHAT WILL WE HAVE FOR THE FUTURE? • FUNGICIDES • YIELD STABILITY • PARTIAL RESISTANCE • COMBINED SINGLE GENES • GENES FROM RELATED SPECIES THE MOST SUCCESFULL APPROCH WILL HAVE ALL IN COMBINATION M MILES, 2003

  34. RESEARCH SUPPORTED BY: • USDA-ARS • USDA CSREES • UNITED SOYBEAN BOARD • REPRESENTATIVES FROM THE CHEMICAL INDUSTRY

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