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3/11/2019
1
Keeping Potatoes Healthy fromPlanting to Harvest
Jeff Miller
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Fusarium sambucinum symptoms
Fusarium coeruleum symptoms
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Fusarium Dry Rot Management
1. Purchase seed with as little dry rot as possible.
2. Sterilize seed cutting equipment.
3. Sharpen seed cutting knives.
4. Avoid pre-cutting, if possible.
5. Treat with an effective seed treatment.
6. Minimize wounding at harvest.
7. Post-harvest treatment with Stadium
Risk of Precut vs. Cut/Plant – F. sambucinum
Cut/Plant
Precut/Store
0
20
40
60
80
100
Check MZ dust Tops Polyram
0 0
18 16
89
44
73
100
%Se
edw
ith
F.sa
mb
uci
nu
m
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6
a
c
bc
b
bc
a
0 20 40 60 80 100
UTC
Maxim MZ (0.5)
Moncoat MZ (0.75)
Maxim 4 FS (0.04)
Maxim 4 FS (0.08)
Quadris IF (8.7)
% of Seed Pieces Decayed
In-furrow applications are not effective.
Effect of Seed Treatments on Fusarium Seed Piece Decay
Which seed treatment do I use?
• Mancozeb (EBDC)
• Fludioxonil/Difenoconazole
– CruiserMaxx Potato Extreme
• Prothioconazole
– Emesto Silver
Also effectiveagainst silver scurf
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Influence of Environment and Seed on Silver Scurf
PN-MMZ
PN-UTCG3-MMZG3-UTC0
10203040506070
Inci
dence
Seed source was more important than location (soil).
Seed treatment effectively reduced disease incidence.
Rhizoctonia on June 21
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Rhizoctonia Stolon Canker
Severe Stem Rhizoctonia
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Untreated Check Priaxor, 6.75 fl oz Quadris, 9.2 fl oz Elatus, 7.7 oz
(Sercadis) (Aprovia + Quadris)
Rhizoctonia Stem Canker - 2018June 13, 49 DAP
ab
ede
c
a
d
b
0
5
10
15
20
25
30
35
40
45
50
UTC Elatus CMPE +Elatus
Quadris Velum Prime Moncut Vertisan
%S
eve
rity
Elatus = benzovindiflupyr + azoxystrobin
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10
Rhizoctonia Stem Canker - 2018July 17, 83 DAP
a
bcc
c
a
b b
0
5
10
15
20
25
30
35
40
45
50
UTC Elatus CMPE +Elatus
Quadris Velum Prime Moncut Vertisan
%S
eve
rity
Elatus = benzovindiflupyr + azoxystrobin
Tuber Quality - 2018
0% 20% 40% 60% 80% 100%
UTC
Elatus
CMPE + Elatus
Quadris
Velum Prime
Moncut
Vertisan
US#1 US#2 < 4 oz Culls
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Tuber Black Scurf - 2018
a
cd d
bcd abc
abab
0
10
20
30
40
50
60
70
UTC Elatus CMPE +Elatus
Quadris Velum Prime Moncut Vertisan
Se
veri
tyIn
de
x
Elatus = benzovindiflupyr + azoxystrobin
Seed Treatments for Rhizoc Canker
0
2
4
6
8
10
12
UTC CMP Extreme Emesto Silver
%R
oo
tSy
stem
Aff
ecte
d
18-Jun 20-Jul
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1. EBDC, fludioxonil/difenoconazole, andpenflufen/prothioconazole effective against dry rot.
2. Fludi/difen and pen/prothio effective against silver scurf andRhizoctonia.
3. In-furrow fungicide applications do not control Fusarium dryrot but can suppress silver scurf and Rhizoc
Seed Treatment/In-Furrow Summary
Pink Rot
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Pink Rot Management
1. Field selection/crop rotation
2. Adjust soil pH by lime application in low pH soils
3. Plant less susceptible varieties
4. Proper irrigation management
5. Use appropriate fungicides
6. Avoid “disease-favorable” conditions at harvest
7. Apply post-harvest fungicides
8. Grade out infected tubers going into storage
9. Reduce tuber pulp temperatures to 55 F or lower
Effect of Fungicide Programs on Pink Rot
May 4In-furrow
July 5Dime-size (DS)
July 19DS + 14 days
Aug 2DS + 28
Aug 16DS + 42
(Untreated check)
RidomilGold
Ridomil Gold Cu, 0.9 kg
MetaStar, 378 ml
Crop-phite, 4.7 L
Crop-phite, 3.5 L
0 2 4 6 8 10
a
bc
bcd
cd
d
ab
Mixed population (mefenoxam sensitive and resistant)
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How important is the time between application and irrigation?
a
b bb
ab
0
1
2
3
4
5
6
7
8
9
10
UTC 48 24 12 6
% Pink Rot
Time between Resist 57 (4.7 L/acre) application and irrigation (center pivot)
Effect of Orondis Gold IF on Pink Rot
a
b
bcd cdd
bc
0
1
2
3
4
5
6
7
Check Orondis Gold(13.8 fl oz/a)
Orondis Gold(10.8 fl oz/a)
Orondis Gold(13.8 fl oz/a) +Ridomil Gold
Bravo (2.5 pt/a)
Orondis Gold(10.8 fl oz/a) +Ridomil Gold
Bravo (2.5 pt/a)
Ridomil GoldBravo (2.5 pt/a)
%P
ink
Ro
tTu
ber
s
In-furrow applications
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Fungicides – Late BlightActive Ingredient Trade Names Relative Activity (1-3) Other Diseases
Cyazofamid Ranman, Torrent 3 None
Zoxamide/mancozeb Gavel 3 Early blight
Cymoxanil Curzate 2 None
Fluazinam Allegro 2 White mold
Phosphonates Confine Extra, Phostrol,Rampart
Foliar = 1Tubers = 3
Pink rot
Dimethomorph Acrobat, Forum, Zampro 2 None
Mandipropamid Revus, Orondis Ultra 3 None
Oxathiapiprolin Orondis Ultra, Orondis Gold 3 Pink rot (OG)
Fluopicolide Presidio Pink rot?
Ametoctradin/dimethomorph Zampro 3 None
Coppers Kocide, Parasol, Coppercide,Cueva, Copper Spray, Copper
1 None
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Fungicides – Pink RotActive Ingredient Trade Names Relative Activity (1-3) Other Diseases
Metalaxyl-M Ridomil Gold 480 SLRidomil Gold MZRidomil Gold Bravo
3 Late blightLate and early blightLate and early blight
Phosphonates Phostrol 2-3 Late blight
Fluopicolide Presidio 1-2 Late blight
Oxathiapiprolin Orondis Ultra, Orondis Gold 3 Pink rot
11 Fungicide classes available.- Many are highly effective
4 Fungicide classes available.- 1 has resistance- 1 works moderately well
How bad does this bother you?
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Avoid Disease Favorable Conditions at Harvest
0
10
20
30
40
50
60
70
16 21
Effect of Wounding and Pulp Temperature on Pink Rot
Wounded
Non-Wounded
0
10
20
30
40
50
60
70
80
90
100
13 16 18 21
%In
cid
ence
Early Storage Temperature (°F)
Tubers Stored from 13 to 21°C After Inoculatedwith Harvest Pulp Temperatures of 16 and 21°C
16 21
Harvest PulpTemperatures
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13 16 18 21(°C)
Post-Harvest Fungicides: Pink Rot and Late Blight
• Phosphorous acid:
– 0.42 L/tonne tubers
– Apply in 2 L water
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Post-Harvest Treatment: Pink Rot
0
20
40
60
80
100
0 1 2 3 4 5 6
%P
ink
RotT
ubers Untreated
HPPA
PA
Post-inoculation Interval (Hours)HPPA = Hydrogen peroxide/peroxyacetic acid (Oxidate)PA = phosphorous acid (Phostrol)
Post-Harvest Treatment: Late Blight
0
20
40
60
80
100
0 1 2 3 4 5 6
%P
ink
RotT
ubers
Untreated
HPPA
PA
Post-inoculation Interval (Hours)HPPA = Hydrogen peroxide/peroxyacetic acid (Oxidate)PA = phosphorous acid (Phostrol)
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Post-Harvest Treatment: Silver Scurf
• Evaluated 2 products(Phostrol/Resist 57)
• 3 rates (325, 416, 499 ml/tonne)
• 3 volumes (1.0, 2.1, 4.2 L/tonne)
• No difference in products used(Phostrol and Resist 57)
0
10
20
30
40
50
60
70
80
% incidence
Phos acidNone
Dry and 0.25 gal/T
Dry and 1.0 gal/T
Dry and 2.0 gal/T
Dry and 0.50 gal/T
Post-harvest spray application volumes
1 L/tonne
2.1 L/tonne4.2 L/tonne
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Questions?