Goss’s wilt: Get the facts! Alison Robertson Charlie Hurburgh Lisa Shepherd Charlie Block and...
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Transcript of Goss’s wilt: Get the facts! Alison Robertson Charlie Hurburgh Lisa Shepherd Charlie Block and...
Goss’s wilt: Get the facts!
Alison RobertsonCharlie Hurburgh
Lisa ShepherdCharlie Block
and Roger Elmore
21 July 2 August 25 August
Goss’s leaf blight disease progress
9 September
Q. Where was Goss’s wilt in Iowa in 2011?
Usually first seen on top leaves
Q. What symptoms occur with Goss’s wilt?
May be seen in mid canopy
Q. What symptoms occur with Goss’s wilt?
Wavy, marginGreasy “Freckles”
Q. What symptoms occur with Goss’s wilt?
“Freckles”
Saprophytic fungi
Q. What symptoms occur with Goss’s wilt?
Q. Is there a kit to diagnose Goss’s wilt?
Clavibacter michiganensis subsp michiganensis
Cost:5 for $32.5025 for $120
5-10 minsImmunoStrip Test (Agdia®)
CAREFUL!!!!!
— False positives
example: Purple leaf sheath; other saprophytic bacteria on corn.
— Extremely sensitive
cross contamination between samples
Purple leaf sheath
Q. Is there a kit to diagnose Goss’s wilt?
ICM 2008
Q. Has a new race of Cmn evolved?
Race: a subgroup or biotype within a species
Usually distinguished from other races by virulencesymptom expressionor host rangebut not by morphology
(D’ Arcy et al. 2001)
ICM 2008
Q. Has a new race of Cmn evolved?
1a 1b 1c 1k 2 3a
3b 3c 4 5 6 7 8
1d C
Standardized soybean lines are used to identify races of P. sojae
ICM 2008
Q. Has a new race of Cmn evolved?
Rpp9 resistance to Southern rust fungus Puccinia polysora
Photo courtesy of B. Dolezal, Pioneer
ICM 2008
Q. Has a new race of Cmn evolved?
Ht1 resistance to Northern leaf blight fungusHelminthosporium turcicum
Race 1 Race 0
Photos courtesy of B. Dolezal, Pioneer
ICM 2008
Q. Has a new race of Cmn evolved?
― 131 strains of Cmn
• 1969 – 2009
• origin
ICM 2008
― Two groups: A and B
A: no correlation with strain,
xxiorigin, history
B: all strains collected after 1999
• 13/69 strains = <20%
(Agrakova et al., 2011)
Cmn bacteria ooze from residue; splash
dispersed
Bacteria overwinter in infested crop
residue and seed
Goss’s disease cycleSymptoms
Epiphytic infection
Infection
― Goss’s wilt bacterium survives for at least 10 xximonths in infested surface crop residue
― Survival is significantly reduced in buried residue
0” 4” 8”Leaves 80 0 0Stalks 75 30 40Cobs 63 5 0Pure culture 0 0 0
Goss’s Disease Index
(Schuster, 1975)
Q. How long does Cmn survive in corn residue?
Can Cmn survive longer?
Survival C. m. subsp. michiganensis on tomato
Buried infested residue: ~7 months
Surface infested residue: 2 years Gleason et al., 1991
What effect might corn stover removal have?
Percent corn residue and GLS disease severity
de Zareno and Lipps, 1993
More residue = greater disease
What effect does manure have on survival of Cmn?
Population of C.m. subsp. sepedonicus on potato decreased as other microbes in cattle manure slurry increased
(Roozen and Vanvuurde 1991)
Composts amended with cattle or poultry manure reduced C. m. subsp. michiganensis of tomato (tomato canker) by 79 to 100%
Populations of C. m. subsp. michiganensis in composts declined to undetectable levels in 15 to 21 days
(Yogev et al, 2009)
Biddle et al, 1990
Q. Was Goss’s wilt introduced on Cmn-infected seed?
Seedborne infection (seed infection): pathogen carried on or in a seed
Seed transmission: pathogen in or on seed infects developing seedlings
Biddle et al, 1990
Inoculated field trialLeaves of plants inoculated at V3, V6 and VTSeed infection: 17.1 - 30.7%Seed transmission: none detected (N=12000 seed)
Biddle et al., 1990
Q. Was Goss’s wilt introduced on Cmn-infected seed?
Natural infection in fieldSeed naturally infected with Goss’s wilt Seed infection: 2 – 39%Seed transmission: 1 in 12864 seedlings.
- single case found in 29% seed lotShepherd, 1999 & 2011
― Several common weeds are secondary hosts of Cmn
i. Green foxtail
ii. Shattercane
iii. Sudangrass
iv. Eastern gamagrass
Q. Are there other hosts of Cmn?
Schuster, 1975
Other susceptible hosts: sugarcane –atypical symptoms
Resistant to infection:• Oats• Barley• Wheat• Bromegrass• Orchardgrass• Crabgrass• Barnyard grass• Proso millet
• Yellow foxtail• Johnson grass• Sugarbeet• cabbage• Chrysanthemum• Poinsettia• Tomato• Petunia• Potato Schuster, 1975
Q. Are there other hosts of Cmn?
— Several genes
— quantitatively inherited
— not complete, i.e. no immunity known
—either leaf blight or wilt
Q. Is there resistance to Cmn?
115 bu/acre yield difference
Effect of Goss’s leaf blight on grain characteristics
— 9 fields
7 in Central IA; 2 in SW Iowa
8 hybrids from 3 major seed companies
— 2 to 11 locations per field
Goss’s leaf blight severity at R3 or R5
Stalk rot severity prior to harvest
20 ears hand harvested per location
r=0.61 P=0.01
Robertson et al., 2011
Goss’s leaf blight severity and stalk rot
Variable <5% at R5 >5% at R5 P value
# rows 16.4(14.5-18.6)
16.9(15.3-17.9) 0.175
# kernels per row 31.9(29.2-34.6)
31.5(29.7-32.6) 0.286
Seed weight (g/1000)
402.4(327.8-472.0)
327.8(245.2-395.6) 0.0001
Robertson et al., 2011
Effect of Goss’s leaf blight on grain characteristics
Assessment <5% at R5 >5% at R5 P value
Test Weight @ 15% moisture (lb/bu)
57.0(55.2-60.3)
55.7(53.6-60.6) 0.049
Starch (%) 60.8(60.1-61.8)
61.3(60.7-62.1) 0.041
Protein, oil and density: NS
Robertson et al., 2011
Effect of Goss’s leaf blight on grain characteristics
r=-0.51 P=0.007
Robertson et al., 2011
8 hybrids
Goss’s leaf blight severity and seed size
r=-0.77 P=0.001
Robertson et al., 2011
2 hybrids
Goss’s leaf blight severity and seed size
r=-0.87 P<0.001
Robertson et al., 2011
2 hybrids
Goss’s leaf blight severity and estimated yield loss
Goss’s leaf blight severity and test weight
r = - 0.83 P=0.0002
Robertson et al., 2011
2 hybrids
Goss’s leaf blight severity and seed infectionGoss's
severity (%)Growth
stage Seed Infection Seed Transmission (positive/ tested)
1 R35 R55 R35 R55 R5
15 R320 R5.2520 R335 R5.75
100 R5.5100 ~R5
Goss’s leaf blight severity and seed infectionGoss's
severity (%)Growth
stage Seed Infection Seed Transmission (positive/ tested)
1 R3 0/2005 R55 R3 0/2005 R5 0/2005 R5 0/200
15 R3 0/20020 R5.2520 R3 0/20035 R5.75 0/145
100 R5.5 1/145100 ~R5 10/400
Goss’s leaf blight severity and seed infectionGoss's
severity (%)Growth
stage Seed Infection Seed Transmission (positive/ tested)
1 R3 0/2005 R5 0/7555 R3 0/2005 R5 0/2005 R5 0/200
15 R3 0/20020 R5.25 0/76820 R3 0/20035 R5.75 0/145 0/1154
100 R5.5 1/145 0/1233100 ~R5 10/400 0/760
Risk factors for Goss’s wilt and leaf blight
Susceptible hybrid
Continuous corn
Percent surface residue
Goss’s wilt in 2011
(Severe storms)
Management in 2012
Resistant hybrid
Rotation
Residue management
Thanks for attending!
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