1. Management of Soybean Rust
Tristan Mueller

2. Life Cycle Uredinia produce urediniospores Infect host
9-10 days to complete one cycle
Uredinia
Urediniospores

3. Yield Loss Potential to cause very large yield losses
Soybean rust trials in FL
Yield Loss
Potential to cause very large yield losses
Typically yield loss is greater the earlier rust is established in field
Rust spreads very quickly (especially within field)
9/25/2006
10/3/2006 -
-talk about draught situation in FL in 2007 where rust came in early, but due to hot and dry weather rust did not develop
-rust has the potential for long range spore dispersal, but typically spreads within a field more quickly.
11/17/2006
10/10/2006

4. Management of soybean rust
Resistance
no commercial varieties available
Fungicides
Triazole
Strobilurin
Co-packs and
premixes
Single site mode of action
More systemic than strobilurins
Protectant and curative activity
Single site mode of action
Locally systemic
Protectant activity
Resistance- currently being worked on, but will not be available for many years

5. Outline What fungicides are available and how effective are they?
When is the best time to apply fungicides?
Can coverage of the soybean canopy be maximized using an air-assist sprayer?
Do we need to improve fungicide coverage to better manage soybean rust and improve yield?

6. Registered fungicides
Available Fungicides
Registered fungicides
Active ingredient
Product (trade name)
azoxystrobin
Quadris
azoxystrobin + propiconazole
Quilt
chlorothalonil
Bravo, Echo, Equus
myclobutanil
Laredo EC, Laredo EW
propiconazole
Tilt, PropiMax, Bumper
propiconazole + trifloxystrobin
Stratego
pyraclostrobin
Headline
tetraconazole
Domark

7. Available Fungicides Section 18 fungicides Active ingredient
Product (trade name)
azoxystrobin + cyproconazole
Quadris Xtra
cyproconazole
Alto
flusilazole
Punch
flutriafol
Topguard
metconazole
Caramba
tebuconazole*
Folicur, Orius, Uppercut
tebuconazole + pyraclostrobin*
Headline SBR
Section 18 labels expire either in 2009 or 2010, except for tebconazole products.
* Section 18 expired so availability will depend on renewal of exemption label – in progress

8. Fungicides in the Pipeline
Active ingredient
Product (trade name)
famoxadone + flusilazole*
Charisma
prothioconazole*
Not available
tebuconazole + trifloxystrobin**
Absolute
* Decision expected in 2008
** Decision depends on status of tebuconazole

9. Product Evaluation Not all available fungicides evaluated in Florida
Most fungicides were very effective
Some products were better than others
I took out which fungicides are better…not sure you want to go there with this crowd. You can maybe point out the better fungicides in the tables on the previous two slides. Take time to explain the aerial shot. I can see differences in defoliation from this picture. When was it taken? Where are the controls, etc….?

10. When is the best time to apply fungicides?
Fungicide Timing
When is the best time to apply fungicides?

11. Methods Locations with rust (6 total) South America (4)
Southern U.S. (2)
Fungicides
Headline (strobilurin)
Folicur (triazole)
Headline SBR (co-pack)
Quilt (premix)
A trial was put together to determine the best time to apply fungicides.
Mention that there also were locations without rust.

12. Methods Timing of application Unsprayed control
Growth stage R1, R3, R5
R1 + R3 + R5
Data collected
Soybean rust severity
Defoliation
Yield
Seed weight
R1 first flowering
R3 pod
R5 pod filling

13. Yield vs. onset of disease
Fungicides were applied 47 days before to 36 days after rust was first reported
Pirapo and Capitan Meza: rust found at GS R2
Florida and Georgia: rust found at GS R4
Bella Vista (both years): rust found at GS R5

14. Rust observed at GS R2 Yield (bu/ac)
R1 timing had highest yield (almost as high as three applications)
R3 timing still protected some yield
R5 timing was not statistically different than the control

15. Rust observed at GS R4 Yield (bu/ac)
R3 (Georgia) or R5 (Florida) timing had the highest yield
All timings were better than the control

16. Rust observed at GS R5 Yield (bu/ac)
Late epidemic with low rust severity gave no difference between timings of single applications of fungicides
Why was there a yield increase? Other diseases observed? Or from rust?

17. Fungicide timing Conclusions
Best timing depends on when rust first infects soybeans and severity of infection
Early infection needs early fungicide application
Later infection the timing is less critical
Better to spray too early instead of too late
Fungicides may differ in sensitivity to timing

18. Florida Quilt Applications
This is an aerial view of the 2006 Quincy, FL location take on 11/17/2007. This location soybean rust was found at GS R4.
Can see differences between fungicides and fungicide timings
I will take you through the plots of 2 fungicides (the best and the worst) at different timings
For Quilt none of the timings protected from defoliation
Yellow=GS R1, Red=GS R3,
Blue=GS R5, and White=non-sprayed control

19. Florida Headline SBR Applications
R3 and R5 better than R1
Yellow=GS R1, Red=GS R3,
Blue=GS R5, and White=non-sprayed control

20. Can fungicide coverage be maximized using an air-assist sprayer?

21. Methods
Urbana, IL
2005 and 2006
Air-assist sprayer (JACTO)

22. Methods
Air-assist blows air over the nozzle which helps propel drops into the canopy
Compared five nozzle types with and without air-assist
Hollow cone
Air Induction
Ultra-Lo Drift
Turbo TeeJet

23. Spray card setup 18 Kromekote cards per plot Placed at  and  canopy
Scan cards to determine percent coverage

24. 2005 Air-assist results
Air-assist
Without Air-assist

25. 2006 Air-assist results
Air-assist
Without Air-assist

26. Air-Assist Sprayer Summary
Less dense canopy
No advantage
Nozzles producing medium-sized drops resulted in the best percent coverage
All nozzles had about the same coverage in the lower canopy
Denser canopy
Better coverage, especially with smaller droplets
JA hollow cone nozzle with air-assist had the best coverage in the upper and lower canopy

27. Fungicide Coverage
Do we need to improve fungicide coverage to better manage soybean rust and improve yield?

28. Methods Florida and Georgia, 2006 Pressures: 30, 50, and 70 psi
Spray volumes: 10 and 20 gpa
Nozzle types: Turbo TeeJet and Ultra Lo-Drift

29. Methods Fungicide: Folicur (tebuconazole) Data collected
Coverage in soybean canopy
Disease severity
Yield

30. Results – Coverage (spray volume)
Upper canopy
Lower canopy
20 GPA treatments averaged twice the coverage of 10 GPA but resulted in equal amounts of fungicide that reached the cards

31. Results – Coverage (pressure)
Upper canopy
Lower canopy
In the upper canopy 70 psi typically had better coverage than 50 and 30 psi
In the lower canopy no differences in coverage among pressures

32. Results – Coverage (nozzle)
Upper canopy
Lower canopy
Turbo TeeJet nozzle has medium droplet spectrum and Ultra Lo-Drift has large droplet spectrum.
Turbo TeeJet had a slight increase in coverage in the upper canopy
In the lower canopy no differences in coverage between nozzles

33. Results – Soybean Rust
No difference among treatments sprayed with fungicides for rust severity
Non-sprayed control had higher rust severity than all of the treatments sprayed with fungicide

34. Results – Yield
No difference among treatments sprayed with fungicides for yield
For both locations, the non-sprayed control had the lowest yield

35. Fungicide Coverage Summary
20 gpa had twice the coverage
10 and 20 gpa results in equal amounts of fungicide on leaves
In general, 70 psi resulted in better coverage
No difference in disease severity or yield

36. Second Coverage Study Florida, 2007
Compare normal fungicide coverage with complete fungicide coverage
Normal = 15 gpa at 35 psi
Complete = 70 gpa with back pack sprayer (all leaves 100% covered)

37. Second Coverage Study
Still no differences

38. Take Home Message
Many fungicides work very well – some better than others
Timing of fungicides are critical for best management of soybean rust
Differences in coverage did not affect efficacy of fungicides

39. Acknowledgements University of Illinois University of Florida
Dr. Glen Hartman
Dr. Carl Bradley
Dr. Loren Bode
University of Florida
Dr. Jim Marois
Dr. David Wright
G. Kelly O’Brien
Maynard Douglas
University of Georgia
Dr. Bob Kemerait
RARS (Zimbabwe)
Dr. Clive Levy
CRIA (Paraguay)
Wilfrido Morel
USDA
Dr. David Walker