Management Options for Soybean Rust; Resistance and Fungicides. Monte R. Miles USDA-Agricultural...
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Transcript of Management Options for Soybean Rust; Resistance and Fungicides. Monte R. Miles USDA-Agricultural...
Management Options for Soybean Rust; Resistance and Fungicides.
Monte R. MilesUSDA-Agricultural Research Service
Department of Crop Sciences National Soybean Research Center
University of Illinois, Urbana, IL
www.soydiseases.uiuc.edu
OBLIGATE PARASITE
UREDINIOSPORES
NO ALTERNATE HOST IS KNOWN
DIRECT PENETRATION
INFECTION CYCLES IN 5 TO 7 DAYS
PHAKOSPORA PACHYRHIZI
C. STONE
São Desidério, Roda Velha, BA, March 8, 2003
J. T. Yorinori
Photo: M. Assunção (Embrapa Soja/CTPA)/José Nunes Jr (CTPA); Campo Alegre, GO
Management of Soybean Rust
• Short-term solutions
– Fungicides
• Long-term solutions
– Host resistance
• Specific resistance
• Partial resistance
– Yield stability
• Combination of fungicides and resistance
RESISTANCE TO SOYBEAN RUST
• SPECIFIC OR SINGLE GENE RESISTANCE
• PARTIAL OR RATE REDUCING RESISTANCE
• YIELD STABILITY OR TOLERANCE
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
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
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
GENE ACCESSION FOUND LOST
Rpp1 PI200492 1960-62 1966
Rpp2 PI230970 1972-74 1978
Rpp3 PI462312 1973-75 1977
Rpp4 PI459025 1980-83 2004
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.
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
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
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
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
EXAMPLE OF PARTIAL RESISTANCE - PUSTULE COUNTS
Entry
Pustules per plant
Pustules per leaf
Pustules at node 7
AGS 129 1,776 41 104
AGS 181 3,849 130 87
GC 82345-20-2 5,934 168 176
GC 82349-6-1 2,108 49 150
KS 8 2,715 76 107
SRE C-56A 803 23 25
SRE C-56E 709 19 29
SRE D-14C 2,159 58 17SRE D-14D 2,100 54 51
G. L HARTMAN
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%)
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
Yield Loss Differences
1 2 3 4 5 6 7 8 9 10 11 120
20
40
60
80
100Y
ield
lo
ss
(%)
Soybean entry
LOW YIELDSTABILITY
MOSTYIELDSTABILITY
GOIAS
Photo: Mauricio Assunção – Embrapa Soja/CTPA; Campo Alegre, GO
MATO GROSSO
Primavera do Leste, MT: 21.02.03
Fungicides will be the primary tool to control Asian soybean
rust in the near future.
FUNGICIDES REGISTERED FOR USE ON SOYBEAN AND LABLED
FOR CONTROL OF SOYBEAN RUST
CHLOROTHALONIL• BRAVO (SYNGENTA)• ECHO ( SIPCAM AGRO)
AZOXYSTROBIN• QUADRIS (SYNGENTA)
FUNGICIDES ON THE SECTION 18 EMERGENCY
EXEMPTION REQUEST
• MYCOBUTANIL * • PROPICONAZOLE *• PYRACLOSTROBIN• PYRACLOSTROBIN + BOSCALID **• TEBUCONAZOLE• TETRACONAZOLE• TRIFLOXYSTROBIN + PROPOCONIZOLE * APPROVED BY EPA, ** BOSCALID IS REGISTERED
ALL FUNGICIDES ARE NOT THE SAME
CURATIVE• ABSORBED• TRANSLOCATES• KILLS FUNGAL
TISSUE • USE AFTER
INFECTION• TRIAZOLES
PROTECTANT• +/-ABSORBED• +/-TRANSLOCATE• PREVENTS INFECTION
OR SPORULATION• USE BEFORE
INFECTION• STROBALURINS AND
CHLOROTHALONILS
FUNGICIDE EFFICACY TRIALS IN SOUTHERN AFRICA AND SOUTH AMERICA
EVALUATE FUNGICIDES THAT ARE LABLED OR ON THE SECTION 18 REQUEST
COMPARISON OF 2 AND 3 APPLICATIONS WITH FIRST APPLICATION SOON AFTER FLOWERING
M. Miles
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.
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
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
OK, SO WHAT DO I USE?THERE ARE MANY QUESTIONS THAT
NEED TO BE AWNSERED FIRSTTHE 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?
HOWCAN WE PENETRATE THE CANOPY?
• AERIAL AND GROUND
• NORMAL AND HIGH VOLUME
• TYPE OF NOZZLE FOR GROUND APPLICATION
M. MILES, 2003
FUNGICIDES ARE USED IN SOYBEAN PRODUCTION IN THE MID AND DEEP SOUTH
• RESULTS ARE MIXED.• QUADRIS• QUADRIS + WARRIOR • NOT ALWAYS
ASSOCIATED WITH PEST CONTROL.
Yield Data From 51 Grower Fields,Yield Data From 51 Grower Fields,2003.2003. Trt. Yield (bu/A) Q+W 53.84 NT 49.21 Q+W Difference +4.63*
*ANOVA P = 0.03 NET GAIN = $15.34
D. HERSHMAN, U OF KY.
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
RESEARCH SUPPORTED BY:
• USDA-ARS• USDA CSREES• UNITED SOYBEAN
BOARD• REPRESENTATIVES
FROM THE CHEMICAL INDUSTRY