Asian Soybean Rust Monitoring in 2005 and 2006

1
Asian Soybean Rust Monitoring in 2005 and 2006

• Dr. Layla Sconyers
• Dr. Robert Kemerait
• Dr. Philip Jost
• Dr. Dan Phillips

Research Associate Extension Plant
Pathology Extension Crop and Soil Science Plant
Pathology
University of Georgia College of Agricultural and
Environmental Sciences
2
Symptoms

• Brick-red spots on upper leaf surface
• Pustules form on lower leaf surface
• Leaves yellow and defoliate
• Confused with other foliar diseases!
• YOUNG infections MAY BE MISSED
• 1-2 pustules per leaf
• Color range clear, tan, red

3
Similar Diseases
Septoria Brown Spot Photo by G. Ruhl
Bacterial Pustule Photo by G. Hartman
Downy Mildew Spores Photo by J. Brock
4
Disease Development

• Fungal spores urediniospores
• Wind or wind-blown rain
• Land on leaf, penetration
• Pustules form after about 10 days
• 1 pustule can produces spores for 3 wks
• More wind more infections
• Canopy closure and crop flowering

400X
60X
5
Disease Development

• Totally defoliates plant or until environment is
  no longer conducive
• 59-84F optimal range, long dew periods
• Defoliation can occur 4-6 wks from initial
  infection

6
2005 Sentinels

• 25 total sentinel plots in GA
• 3 clover
• 5 kudzu
• 17 soybean sentinels
• Sentinels scouted weekly
• Soybean 50 X 50 plots
• MG II, III, IV planted from 1st to 3rd wk of April

D. Hershman
7
2005 Disease Monitoring

• 100 leaves or leaflets examined
• Visually
• Dissection microscopy (60-80X)
• Soybean 40 lower, 40 mid, 20 upper canopies
  100 leaflets
• Severity (low, moderate, or heavy)
• Incidence (leaflets infected of total collected)
• First finds for each county were confirmed by PCR
  or UGA trained expert

8
2005 Spore Trapping

• 10 spore traps provided by Syngenta
• Placed in center of each soybean sentinel
• Slides changed weekly
• Analyzed by J. Rupe, U. Ark.

D. Hershman
9
2005 Spore Trapping
Spore traps were placed at 6, 7, 8, 10, 16, 17,
18, 22, 23, and 25 on map
10
What happened in 2005?Disease Monitoring

• Clover no rust
• Kudzu 1 of 5 sites had rust
• Soybean 13 of 17 sites had rust
• First find Seminole County
• First sentinel Tift County, Lang Research Farm
• First commercial farm Appling County
• 33 counties by Nov 3
• 60 miles per wk

11
(No Transcript)
12
What happened in 2005? Spore Trapping
13
2006 Sentinels

• Number based on funding from USDA and NCSRP
• At least 22 in Georgia
• Clover or lupine
• Kudzu
• Overwintering sentinels
• 10 in Georgia
• Soybean
• Disease monitoring
• Spore trapping

14
2006 Sentinels

• Protocol modified
• Scouting interval every two weeks until bloom
• Collect 100 leaflets from lower soybean canopy
• Dissection microscopy (40 60X)
• Incubation (24-48 hr)
• Need for education and training

Yorinori
15
Summary

• Rust can be detrimental if undetected and infects
  early in growing season (S. America)
• Rust CAN be managed
• Proactive scouting and monitoring needs to
  continue in 2006
• Communication with county agents and extension
  specialists need to know what to scout for!
• Timely fungicide applications with good products
  1st application VERY important
• Still a learning processwe do not have all the
  answers yet

16
Acknowledgements

• Georgia
• Bob Kemerait, Dan Phillips, Phil Jost, Roger
  Boerma, Jason Brock, John Sherwood, Rick Jackson,
  Michael Foster
• Growers Mr. Billy Wayne Sellers, Mr. Glen Waller,
  Mr. Vic Thigpen
• Research farm managers and their crews
• County agents
• John Rupe, U. Arkansas
• USDA and NCRSP
• Syngenta