1. Asian Soybean Rust University of Illinois State Soybean Rust Taskforce
Suzanne Bissonnette,
IPM Educator

2. Soybean Rust Pustules Underside Leaf

4. Predicted Spore Deposition by a Hypothetical Hurricane
Weather-Based Assessment of Soybean Rust Threat to North America, Final Report to
APHIS, 15 July 2004, Scott Isard, et al.

7. Hurricane “Ivan” the Terrible Modeled Spore Deposition
Map
December 3, 2004
As 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 plan
Collaboration of state, federal, university, private, grower and applicator organizations
Initial detection, diagnosis, and confirmation
Field  DDDI  plant clinic national mycologist  notification management

10. Soybean Rust Identification
Two species differentiated based on microscopic morphological differences in teliospore characteristics
Phakopsora meibomiae (mild)
Phakopsora pachyrhizi (Asian Soybean Rust, severe)
Ono, Buriticá and Hennen
Cross-section uredia
Cross section telia

11. Spread of Soybean Rust
Natural –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.

12. Hosts of Soybean Rust (>90)
Legumes (Papilionoideae)
Cultivated Crops:
Soybean Glycine max
Lima & butter bean Phaseolus lunatus
Green & kidney bean Phaseolus vulgaris
Cowpea Vigna unguiculata
Pigeon pea Cajanus cajan
Yam bean, jicama Pachyrhizus erosus
Ornamental plants:
Hyacinth bean, lupine,
royal poinciana
Wild hosts:
Kudzu, sweet clover
Kudzu infected with soybean rust

13. Kudzu : Pueraria montana var lobata (Willd.) Maesen & S. Almeida

14. Kudzu population
Distribution and
Rust detections
December 6, 2004

15. Asian Soybean Rust on Kudzu over wintering host, early inoculum source?

16. Yield Loss From Soybean Rust Is a Result Of:
Premature defoliation
Increase in number of unfilled pods/plant
Decrease in # of seeds/plant
Decrease in seed weight
Decrease in germinability of seed
Yield losses begin at approx. 3% severity

17. Management of Soybean Rust, Illinois Research program
Short-term solutions
Fungicide evaluations
Long-term solutions
Host resistance
Specific resistance
Partial resistance
Yield stability (tolerance)
Introduction of resistance from other sources
Combination of fungicides and resistance
Glen 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 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

19. Major Genes for Resistance & Year They Were Defeated
Original Source
Resistant
Susceptible
Year ID (ineffective)
Rpp1
PI Komata
In 73-1*
Tw 72-1 Immune
Tw 80-1
(1966)
Rpp2
PI230970
Tw 72-1 Pp 77-1*
(1978)
Rpp3
PI Ankur
Tw 72-1
(1977)
Rpp4
PI Bing Nan
Tw 80-2*
Tw 72-1*

20. Evaluation of U.S. And Exotic Germplasm for Resistance to Soybean Rust & Disease Management Strategies
Determine the resistance/susceptibility of soybean varieties currently grown in the U.S. to soybean rust
Identify resistance in the germplasm
Evaluate 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 in
continental US where
Soybean rust research
has been allowed to date

22. Identified Partial Resistance (epidemic is slowed due to fewer pustules or spores)
Entry
Pustules per plant
Pustules per leaf
Pustules at node 7
AGS 129
1,776 41
104
AGS 181
3,849
130 87 GC
5,934
168
176 GC
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 17
SRE D-14D
2,100 54 51

23. Rust Phenotypes pustule types for evaluation in greenhouse or field
Tan pustule
A fully susceptible reaction
Reddish brown pustule (RB)
Indicates some type of resistance
Tan
Reddish Brown (RB)

24. Significant Variation by Location

25. Preliminary Summary of Field Evaluations
Not one soybean accession was found to be resistant at all locations
Known 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 screen
212 were screened an a second single plant screen, with two inoculation dates, 14 and 28 days after planting
None were resistant
C Stone

27. Brand New Editions Be ready with effective scouting

28. Disease Scouting for Soybean Rust**
Typical disease patterns
Random spots in field with diffuse borders **
Field edges
Whole field**
Patterned
Headlands, historical, mechanical
Low / 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 population
ie 47 of 100 plants diseased= 47% incidence
ie 34 of 100 leaflets diseased= 34% incidence
Severity:
The measure of actual damage done by disease
Some keys measure severity of the whole plant
Some 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 plants
Examine the undersides of leaves for pustules.
If you suspect rust
collect 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 Process
digital images submitted for you by Unit
Diagnosis reply to Unit
Samples 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 DDDI
Expect 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 defoliation
Observe chlorosis
Look at underside of leaves
Observe pustules with hand lens

39. Soybean Rust Pustules Underside leaves*, Stems, Petioles, Cotyledons

40. Other Soybean Diseases that Can Be Confused with Soybean Rust
Septoria Brown Spot
J. Pataky U of I

41. Other Soybean Diseases that Can Be Confused with Soybean Rust
Bacterial Pustule
Bacterial 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
+/- translocated
Prevent infection or sporulation
Use before infection
Strobilurins, chlorothalonils
Curative
Absorbed
Translocate
Kill fungal tissue
Use after infection
Triazoles

45. Fungicides Registered for Treatment of Soybean Rust or With EPA Section 18
Fungicide **
Trade Name
Family
Action
Chlorothalonil
Bravo Weather Stik, Echo 720 & 90DF
Chloronitriles
(Benzonitriles)
Protectant
Azoxystrobin
Quadris
Strobilurin
Pyraclostrobin
Headline
Myclobutanil
Laredo EC & EW
Triazole
Curative
Propiconizole
Tilt, Propimax, Bumper
Tebuconazole
Folicur
**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 Name
Family
Action
Pyraclostrobin + Boscalid
Pristine, pending?
Strobilurin + Carboximide
Protectant
Tetraconazole
Domark, pending
Triazole
Curative
Propiconizole + Trifloxystrobin
Stratego, approved
Triazole + Strobilurin
Curative + Protectant
Azoxystrobin + Propiconizole
Quilt pending
( oz) 0.5% COC
NOTE: 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. Africa
General Brazil (J. Yorinori):
Application at first detection
Second spray days later for protective fungicides
20-25 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 fungicide
General Zimbabwe (C. Levy, M. Miles, G. Hartman):
Apply first spray soon after flowering
Apply second application days later
Third 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 /season
Curative (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 Expected
Rust expected, not yet present
Apply Protectant Fungicide (Benzonitriles, Strobilurins)
Disease still expected now need 2nd spray
Apply Curative (Triazole)

50. What Should We Do in Illinois?
Scenario B
Disease expected & develops after 1st application
Disease expected not yet present
Strobilurin, Benzonitriles
Disease expected or now present need 2nd spray
Triazole
Disease still present need 3rd application
Benzonitriles (PHI), Triazole

51. Prepare Yourself for Soybean Rust Before It Arrives
Equip sprayers with proper nozzles
Pre-plan fungicide spray program
Who? How much acreage/day?
Plan to scout “Low as you go” weekly
Take representative sample
Get it properly identified
Manage 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. Montgomery
Acknowledge slides & jpg’s from G. Hartman, M. Miles, USDA-ARS, Oregon State Univ., R. Frederick, M. Palm, University of Illinois Extension