7 Hurricane “Ivan” the Terrible Modeled Spore Deposition MapDecember 3, 2004As presented in: US Soybean Rust Detection and Aerobiological Modeling, November, 2004,
8 Soybean Production Distribution and Rust detections December 6, 2004
9 Action Plan for Soybean Rust Illinois state rust taskforce planCollaboration of state, federal, university, private, grower and applicator organizationsInitial detection, diagnosis, and confirmationField DDDI plant clinic national mycologist notification management
10 Soybean Rust Identification Two species differentiated based on microscopic morphological differences in teliospore characteristicsPhakopsora meibomiae (mild)Phakopsora pachyrhizi (Asian Soybean Rust, severe)Ono, Buriticá and HennenCross-section urediaCross section telia
11 Spread of Soybean RustNatural –windborne urediniospores produced in large quantities under moderate temperatures and high humidity. Life cycle ~7-10 days, infection to spore production.Artificial – movement of infected live plants, leaf material, pods, and stems.Soybean Rust is not seed borne.Soybean Rust will not over winter on dead plants.
15 Asian Soybean Rust on Kudzu over wintering host, early inoculum source?
16 Yield Loss From Soybean Rust Is a Result Of: Premature defoliationIncrease in number of unfilled pods/plantDecrease in # of seeds/plantDecrease in seed weightDecrease in germinability of seedYield losses begin at approx. 3% severity
17 Management of Soybean Rust, Illinois Research program Short-term solutionsFungicide evaluationsLong-term solutionsHost resistanceSpecific resistancePartial resistanceYield stability (tolerance)Introduction of resistance from other sourcesCombination of fungicides and resistanceGlen L. Hartman1, Monte Miles1, and Reid Frederick2, 1USDA-Agricultural Research Service,Department of Crop Sciences, National Soybean Research Center University of Illinois, Urbana, IL,2FDWSR, Fort Detrick, Frederick, MD
18 Breeding Programs Historical Screening of Germplasm Initial studies1961 ≈ 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
19 Major Genes for Resistance & Year They Were Defeated Original SourceResistantSusceptibleYear ID (ineffective)Rpp1PI KomataIn 73-1*Tw 72-1 ImmuneTw 80-1(1966)Rpp2PI230970Tw 72-1 Pp 77-1*(1978)Rpp3PI AnkurTw 72-1(1977)Rpp4PI Bing NanTw 80-2*Tw 72-1*
20 Evaluation of U.S. And Exotic Germplasm for Resistance to Soybean Rust & Disease Management StrategiesDetermine the resistance/susceptibility of soybean varieties currently grown in the U.S. to soybean rustIdentify resistance in the germplasmEvaluate 16,000 accessions in the USDA National Soybean Collection (Fort Detrick)Evaluate reported sources of resistance (Fort Detrick & international locations)Evaluate yield stability (tolerance)Frederick, Bonde, Yang & Hartman, UBS Supported)
21 Fort Detrick Maryland Containment Research Facilities (secured greenhouse etc.) Only location incontinental US whereSoybean rust researchhas been allowed to date
22 Identified Partial Resistance (epidemic is slowed due to fewer pustules or spores) EntryPustules per plantPustules per leafPustules at node 7AGS 1291,77641104AGS 1813,84913087GC5,934168176GC2,10849150KS 82,71576107SRE C-56A8032325SRE C-56E7091929SRE D-14C2,1595817SRE D-14D2,1005451
23 Rust Phenotypes pustule types for evaluation in greenhouse or field Tan pustuleA fully susceptible reactionReddish brown pustule (RB)Indicates some type of resistanceTanReddish Brown (RB)
25 Preliminary Summary of Field Evaluations Not one soybean accession was found to be resistant at all locationsKnown single genes had less disease severity in some sites, but also TAN and RB lesions at other sites
26 B. US Commercial Variety Entries 940 cultivars were screened in a single plant screen212 were screened an a second single plant screen, with two inoculation dates, 14 and 28 days after plantingNone were resistantC Stone
27 Brand New Editions Be ready with effective scouting
28 Disease Scouting for Soybean Rust** Typical disease patternsRandom spots in field with diffuse borders **Field edgesWhole field**PatternedHeadlands, historical, mechanicalLow / high spots** Expect these patterns for rust
29 Assessment of Disease Incidence: Severity: The number of plants (or units) affected by disease with in a populationie 47 of 100 plants diseased= 47% incidenceie 34 of 100 leaflets diseased= 34% incidenceSeverity:The measure of actual damage done by diseaseSome keys measure severity of the whole plantSome keys measure severity on infected leaves
30 Assessment of Rust Severity Researchers generally assess rust disease as disease severity of key leaves.Rust pustules only occupy a maximum of 37% of the area on a leaf. This is equivalent to 100% infection of that leaf.
31 Rust Severity Assessment Key A= actual amount of tissue occupied by pustules (Cobb scale)B= equivalent damage to leaf (Modified Cobb)* If A=18.5% area occupied by pustules, this is equivalent to B=50% damage to the leaf*
32 Disease Scouting for Soybean Rust Incidence U of I currently recommends determining incidence rather than severity for scouting protocol.Examine 20 plants in 5 random locations in a field.Note: one plant with any amount of rust in 100 plants = 1% incidence
33 Soybean Rust Scouting Field Pattern Scout in a zig-zag pattern in the field making observations of 20 plants in 5 locations
34 Illinois Scouting – “Look Low As You Go” When scouting examine the lower quarter of soybean plantsExamine the undersides of leaves for pustules.If you suspect rustcollect 20 leaflets exhibiting symptoms.Place flat, dry leaflets between paper towels.Double bag suspect leaflets in zip lock bags.Clearly label sample.
35 IL Extension Distance Diagnostics (DDDI Available in all Units in Illinois) Sample Processdigital images submitted for you by UnitDiagnosis reply to UnitSamples may then require submission to U of I Plant Clinic.
36 IL Extension Distance Diagnostics (DDDI Available in all Units in Illinois) No fee for DDDI samples.Plant Clinic fee ($12.50) paid by ISPOB if sample is pre-screened with DDDIExpect to pay overnight shipping prior to detection in state.
37 Foliar Symptoms Soybean Rust not distinguishing must look closer
38 Symptoms & Signs of Soybean Rust Look for pustules and chlorosis on undersides of lower leaves before flowering.Severity increases with time and rainfall – lesions can develop on all leaves followed by defoliationObserve chlorosisLook at underside of leavesObserve pustules with hand lens
40 Other Soybean Diseases that Can Be Confused with Soybean Rust Septoria Brown SpotJ. Pataky U of I
41 Other Soybean Diseases that Can Be Confused with Soybean Rust Bacterial PustuleBacterial Blight
42 Other Soybean Diseases that Can Be Confused with Soybean Rust Downy Mildew
43 Un-treated Strip Between 2 Fields in South America
44 What You Need to Know About Rust Fungicide Types Protectant+/- absorbed+/- translocatedPrevent infection or sporulationUse before infectionStrobilurins, chlorothalonilsCurativeAbsorbedTranslocateKill fungal tissueUse after infectionTriazoles
45 Fungicides Registered for Treatment of Soybean Rust or With EPA Section 18Fungicide **Trade NameFamilyActionChlorothalonilBravo Weather Stik, Echo 720 & 90DFChloronitriles(Benzonitriles)ProtectantAzoxystrobinQuadrisStrobilurinPyraclostrobinHeadlineMyclobutanilLaredo EC & EWTriazoleCurativePropiconizoleTilt, Propimax, BumperTebuconazoleFolicur**Section 3 compounds in green, others Section 18 (1/19/05)NOTE: only a total of 2 applications of Sec 18 products are allowed in 1 season
46 Additional Fungicides That Have or May Get EPA Section 18’s Trade NameFamilyActionPyraclostrobin + BoscalidPristine, pending?Strobilurin + CarboximideProtectantTetraconazoleDomark, pendingTriazoleCurativePropiconizole + TrifloxystrobinStratego, approvedTriazole + StrobilurinCurative + ProtectantAzoxystrobin + PropiconizoleQuilt pending( oz) 0.5% COCNOTE: only a total of 2 applications of Sec 18 products are allowed in 1 season
47 Fungicides Strategy for Soybean Rust Management in S. America, S Fungicides Strategy for Soybean Rust Management in S. America, S. AfricaGeneral Brazil (J. Yorinori):Application at first detectionSecond spray days later for protective fungicides20-25 days later for protective/curative fungicides.Timing of the first spray depends on when the first infection is detected, weather conditions, and mode of action of the fungicideGeneral Zimbabwe (C. Levy, M. Miles, G. Hartman):Apply first spray soon after floweringApply second application days laterThird application only in a severe epidemic
48 Fungicide Spray Recommendations (lessons from other countries) Protectant (strobilurins,chloronitriles): Apply prior to infection. Strobilurins loose effectiveness after 3-5% severity. Strobilurins no more than once /seasonCurative (triazoles): Apply when rust is present. After 10% severity triazoles may not provide full yield protection.
49 What Should We Do in Illinois? Scenario A:Disease ExpectedRust expected, not yet presentApply Protectant Fungicide (Benzonitriles, Strobilurins)Disease still expected now need 2nd sprayApply Curative (Triazole)
50 What Should We Do in Illinois? Scenario BDisease expected & develops after 1st applicationDisease expected not yet presentStrobilurin, BenzonitrilesDisease expected or now present need 2nd sprayTriazoleDisease still present need 3rd applicationBenzonitriles (PHI), Triazole
51 Prepare Yourself for Soybean Rust Before It Arrives Equip sprayers with proper nozzlesPre-plan fungicide spray programWho? How much acreage/day?Plan to scout “Low as you go” weeklyTake representative sampleGet it properly identifiedManage resistance to fungicides, follow label
52 Presentation by S. Bissonnette, D. Bowman, D. Malvick, M. Montgomery Acknowledgements:Presentation by S. Bissonnette, D. Bowman, D. Malvick, M. MontgomeryAcknowledge slides & jpg’s from G. Hartman, M. Miles, USDA-ARS, Oregon State Univ., R. Frederick, M. Palm, University of Illinois Extension
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