Transcript Document

Asian Soybean Rust
University of Illinois
State Soybean Rust Taskforce
Suzanne Bissonnette,
IPM Educator
Soybean Rust Pustules
Underside Leaf
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.
Hurricane “Ivan” the Terrible
Modeled Spore Deposition
Map
December 3, 2004
As presented in: US Soybean Rust Detection and Aerobiological Modeling, November, 2004,
http://www.aphis.usda.gov/lpa/issues/sbr/sbr.html
Soybean
Production
Distribution
and Rust
detections
December 6,
2004
Action Plan for Soybean Rust
• Illinois state rust taskforce plan
– http://www.agr.state.il.us/regulation/soybeanrustprogram.pdf
• Collaboration of state, federal, university,
private, grower and applicator organizations
• Initial detection, diagnosis, and confirmation
–
Field  DDDI  plant clinic national
mycologist  notification management
Soybean Rust Identification
Two species
differentiated based
on microscopic
morphological
differences in
teliospore
characteristics
Cross-section uredia
Phakopsora meibomiae (mild)
Phakopsora pachyrhizi (Asian
Soybean Rust, severe)
Ono, Buriticá and Hennen - 1992
Cross section telia
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.
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
Kudzu : Pueraria montana var
lobata (Willd.) Maesen & S. Almeida
Kudzu population
Distribution and
Rust detections
December 6, 2004
Asian Soybean Rust on Kudzu
over wintering host, early inoculum source?
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
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
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
Major Genes for Resistance
& Year They Were Defeated
Gene
Original
Source
Resistant
Susceptible
Year ID (ineffective)
Rpp1
PI200492
Komata
In 73-1*
Tw 72-1
Immune
Tw 80-1
1960-62
(1966)
Rpp2
PI230970
In 73-1*
Tw 72-1
Pp 77-1*
Tw 80-1
1972-74 (1978)
Rpp3
PI462312
Ankur
In 73-1*
Tw 72-1
Tw 80-1
1973-1975
(1977)
Rpp4
PI459025
Bing Nan
Tw 80-2*
Tw 72-1*
In 73-1*
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)
Fort Detrick Maryland Containment
Research Facilities (secured greenhouse etc.)
• Only location in
continental US where
Soybean rust research
has been allowed to
date
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 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
SRE D-14D
2,100
58
54
17
51
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)
Significant Variation by Location
Distribution of 174 soybean accessions when placed into
six classes after evaluation of soybean rust severity at
four locations in 2002-2003
120
China
Paraguay
Brazil
Maryland
Number of individuals
100
98
80
60
60
54
45
42
40
25
19
20
0
31
11
1
0 0
Immune
6
24
37
36
33
33
25
17
0
Resistant
5
Moderately
resistant
5
Moderately
susceptible
Soybean rust rating class
Susceptible
0
Highly
susceptible
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
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
C Stone
• None were
resistant
Brand New Editions
Be ready with effective scouting
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
Assessment of Disease
• Incidence:
– 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
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.
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
*
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
Soybean Rust Scouting Field
Pattern
• Scout in a zig-zag
pattern in the field
making observations
of 20 plants in 5
locations
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.
IL Extension Distance Diagnostics
(DDDI Available in all Units in Illinois)
Sample Process
• digital images
submitted for you
by Unit
• Diagnosis email
reply to Unit
• Samples may then
require submission
to U of I Plant
Clinic.
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.
Foliar Symptoms Soybean Rust
not distinguishing must look closer
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
Soybean Rust Pustules
Underside leaves*, Stems, Petioles, Cotyledons
Other Soybean Diseases that Can Be
Confused with Soybean Rust
• Septoria Brown Spot
J. Pataky U of I
Other Soybean Diseases that Can Be
Confused with Soybean Rust
• Bacterial Pustule
• Bacterial Blight
Other Soybean Diseases that Can Be
Confused with Soybean Rust
• Downy Mildew
Un-treated Strip Between 2
Fields in South America
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
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
Protectant
Pyraclostrobin
Headline
Strobilurin
Protectant
Myclobutanil
Laredo EC & EW
Triazole
Curative
Propiconizole
Tilt, Propimax,
Bumper
Triazole
Curative
Tebuconazole
Folicur
Triazole
Curative
**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
Additional Fungicides That Have or
May Get EPA Section 18’s
Fungicide**
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
(6.2-12 oz)
0.5% COC
Triazole +
Strobilurin
Curative +
Protectant
NOTE: only a total of 2 applications of Sec 18 products are allowed in 1 season
Fungicides Strategy for Soybean Rust
Management in S. America, S. Africa
•
•
•
•
•
General Brazil (J. Yorinori):
Application at first detection
Second spray 15-20 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 14-20 days later
Third application only in a severe epidemic
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.
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)
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
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
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