Silver scurf, black scurf and dry rot · Silver scurf, black scurf and dry rot Ragnhild Nærstad...

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Silver scurf, black scurf

and dry rot

Ragnhild Nærstad

Norwegian Institute for Agricultural and

Environmental Research

Bioforsk

Plant Health and Plant Protection Division

14 000 ha -> 350 000 tons = 25 t/ha (10 – 70 t/ha)

3000 growers, 1 – 80 ha of potatoes per grower

Silver scurf Helminthosporium solani

Silver scurf

• Potato is the only known host plant

• Survives as a saprophyte in soil, and multiplies

on senescent plants of many species

• Tubes can become infected in the growing

season, at harvest or during storage

• Needs humid conditions to infect, the infection

speed increases with temperature

• Under optimal conditions the fungus needs

9 hours to penetrate into the cells

Silver scurf

• Infected cells die, loose their pigments and

become filled with air –> silvery lesions

• Increased the water loss in infected tissue ->

shrinking

• Inoculum sources: Seed tubers (and soil)

• PCR results from 2008 - 2009: a lot of

inoculum in seed tubers and low levels in

Control measures – Silver scurf

• Crop rotation + avoid cereals as the last crop before

potatoes

• Shorter growing seasons (presprout seed tubers)+

shorten the period between haulm killing and harvest

• Suppressive soils

• Low plant density

• Dry curing

• Cold storage and no condense

• Seed treatment: Fungazil (imazalil), Maxim

(fludioxonil), Emesto (penflufen), Emesto silver

(penflufen + protioconazol), Serenade (Basillus subtilis)

• In furrow fungicide application: Amistar (azoxystrobin)

Black scurf

Rhizoctonia solani

Sclerotia and

Black scurf Rhizoctonia solani

(Thanatephorus cucumeris)

• Sunken dark brown lesions on

sprouts, stems, stolons and roots

• Infections in stolons early in the

season -> tuber abortion, new

tubers is developed higher up ->

more small tubers and more green

tubers

Control measures – Black scurf

• Crop rotation, several years without potatoes

• Suppressive soils

• Shorter growing seasons + shorten the period between

haulm killing and harvest -> less sclerotia on tubers

• Dry curing

• Cold storage and no condense

• Seed treatment: Rizolex (tolclofosmethyl), Monceren

(pencycuron), Maxim (fludioxonil), Emesto

(penflufen), Emesto silver (penflufen + protioconazol)

Silver scurf

Black dot

Plug test - incubation test

- distinguish between different types of scurfs

- visualize latent infection

Occurrence of skin blemish diseases in Norway

after 4 - 6 month of storage, 247 potato lots: Nærstad R, Dees MW, Le VH, Holgado R, Hermansen A

• Silver scurf (Helminthosporium solani) 11-13% (100%)

• Black dot (Colletotrichum coccodes) (80%)

• Common scab (Streptomyces spp.) 6-7% (50-70%)

• Powdery scab (Spongospora subterranean) 0.7-2% (70%)

• Skin spot (Polyscytalum pustulans) 0.2-1.7% (80%)

• Black scurf (Rhizoctonia solani) 0.8% (80%)

Root lesion nematodes

Paratylenchchus spp. in

60% of scabby lesions

Decision making in potato skin blemish

diseases control using real-time diagnostic

methods; Norwegian results from 2009 and

R. Nærstad, A. Hermansen, V.H. Le,

G. Lund, M. Skogen, M.B. Brurberg

Sampling

• 40 locations each year in 2009 and 2010 + questionaries

• From each location:

– Samples of soil and seed tubers at planting

– Samples of soil in August

– Samples of progeny tubers at harvest

• Assessed for the presence of pathogens by real-time PCR

• Tubers were also assed for the presence of pathogens by plug tests

• Pathogens:

• Black dot (Colletotrichum coccodes)

• Skin spot (Polyscytalum pustulans)

• Common scab (Streptomyces spp.)

• Silver scurf (Helminthosporium solani)

• Powdery scab (Spongospora subterranean)

• Black scurf (Rhizoctonia solani)

Real-time PCR protocols

• SCRI protocols:

• Common scab (Cullen and Lees, 2007)

• Powdery scab (van de Graaf et al., 2003)

• Silver scurf (Cullen et al., 2001)

• Black scurf (Lees et al., 2002)

• Black dot (Cullen et al. 2002)

• Fungal pathogens based on ITS regions

• Streptomyces based on nec gene

18S gen 5.8S gen 26S gen

ITS Ribosomale RNA gener:

DNA-analysis

• Soil samples (SCRI protocol)

• Tuber samples

– Peel homogenized in Homex (SCRI protocol)

– Extraction robot (Molgene)

Example of amplification plot

Silver scurf Helminthosporium solani

543210

PCR-Silver scurf-progeny tubers

Scatterplot of %S-Silver scurf-progeny vs PCR-Silver scurf-progeny

• Good correlation between plug-test and PCR results

• High level of inoculum in seed tubers

• Low level of inoculum in soil

• Low correlation between inoculum in seed tubers and progeny tubers

543210

PCR-Silver scurf-progeny tubers

Scatterplot of PCR-Silver scurf-seed tu vs PCR-Silver scurf-progeny

5,65,24,84,44,0

PCR-Silver scurf-seed tubers

Scatterplot of %S-Silver scurf-seed tub vs PCR-Silver scurf-seed tu

Black scurf Rhizoctonia solani

6543210

PCR-black scurf- seed tubers

Scatterplot of Sclerotia- Seed tubers vs PCR-black scurf- seed tubers

• Good correlation between: sclerotia plug-test plug-test PCR results

• Low level of inoculum in soil in spring, a slight increase in the autumn, but did not correlate with the black scurf in the progeny

• Low correlation between inoculum in seed and progeny tubers

6543210

PCR-black scurf- seed tubers

Scatterplot of %R-Black scurf-seed tube vs PCR-black scurf- seed tu

9080706050403020100

%R-black scurf-progeny tubers

Scatterplot of Sclerotia-progeny tubers vs %R-black scurf-progeny t

Conclusion from quantitative PCR

diagnostics of soil and tubers

• Skin spot, powdery scab and black dot:

disease increased with inoculums on the seed

tubers.

• For black dot and powdery scab it also

increased with soil inoculums

• Common scab, silver surf and black scurf:

other factors than inoculums level were more

important for disease incidence in the progeny

tubers

Harvest, curing and storage strategies

3 trials

• 0, 11 and 22 days from haulm killing to

harvest

• 4 harvest dates

• Curing: 70% RH and 90% RH

• Storage: Directly to 4oC and slowly to 4oC

Seed treatment at planting (6 trials/year)

% progeny tubers with sclerotia (2005 and 2006)

% plugs with black scurf hyfae (2007)

% plugs with silver scurf (2007)

Control

Rizolex

• Both Maxim (fludioxonil) and Rizolex

(tolclofosmethyl) reduces black scurf in the progeny

tubers (sclerotia og hypha)

• Maxim reduces silver scurf in the progeny

% plugs with silver scurf % plugs with black scurf hyfae

% plugs with skin spot

Effect of humidity during curing and Amistar in furrow

Control Humid curing

Control Dry curing

Amistar Humid curing

Amistar Dry curing

• All treatments reduced the

amount of R. solani sclerotia

and hypha on the progeny

tubers

• Amistar and Emesto also

reduced the frequency of

silver scurf latent infections

(plug test)

• In 2008 and 2010 there were

attack of black dot at one

location and in these trials

there were less black dot in

the Amistar treatment.

2008 2009 2010

% reduction of black scurf hyfae

Rizolex

Emesto

Amistar

Emesto dust

Emesto silver

Prestige

2008 2009 2010

% reduction of silver scurf

Rizolex

Emesto

Amistar

Emesto dust

Emesto silver

Prestige

2008 2010

% reduction of black dot

Rizolex

Emesto

Amistar

Emesto dust

Emesto silver

Prestige

Fusarium dry rot

• Important disease of potato affecting tubers in

storage

• Caused by several fungal species in the genus

Fusarium

• Fusarium dry rot of seed tubers can reduce crop

establishment by killing developing potato sprouts

• Crop losses can be up to 25%

Symptoms

• Originate in wounds created by mechanical damages or

desprouting during handling

• Surface lesions appears as dark depressions and wrinkled

areas of skin

• Concentric rings can be observed in case of heavy infection

• Fusarium dry rot can be recognized based on white, pink or

orange colored mycelium proliferation on the tuber surface

Photos: J. Gomez

Fusarium dry rot in Norway

P.H. Jensen, M.B. Brurberg & A. Hermansen • Main goal: Find out which

Fusarium spp. currently causes

dry rot problems in Norway

• How: Potato samples collected

from different regions in Norway

over 3 seasons (2010-2013)

– artificial wounding +

incubation

– isolation

Photo: P. H. Jensen

Results from the growing season 2010 -2011

5 % of the tubers developed rots

Fusarium

Boeremia (Phoma)

Penicillium

Cylindrocarbon

49 % of rots were caused by Fusarium

–F. coeruleum (64%)

–F. avenaceum (31%)

–F. culmorum (4%)

–F. cerealis (1%)

–F. sambucinum (1%)

Photo: P. H. Jensen

Fusarium sambucinum Fusarium culmorum

Fusarium coeruleum Fusarium cerealis

• Develop multiplex real time PCR for

Norwegian dry rots caused by Fusarium

species and gangrene (Boremia foveata)

Monceren FS 250(Pencycuron) Inhibition of cell division, phenylureas,

FRAC Code B4

0,01 0,10 1,00 10,00 100,00

Monceren FS250 (Pencycuron in ppm )

Colletotrichum coccodes

No08-Cc-016

No08-Cc-037

No08-Cc-057

No08-Cc-10

No08-Cc-13

No08-Cc-19

No08-Cc-42

No08-Cc-43

No08-Cc-47

No08-Cc-50

0,01 0,10 1,00 10,00 100,00

Helminthosporium solani

No08-Hs-059

No08-Hs-060

No08-Hs-062

No08-Hs-067

No08-Hs-020

No08-Hs-021

No08-Hs-027

No08-Hs-029

No08-Hs-035

No08-Hs-041

0,01 0,10 1,00 10,00 100,00

Polyscytalum pustulans

No08-Pp-034

No08-Pp-043

No08-Pp-048

No08-Pp-053

No08-Pp-001

No08-Pp-005

No08-Pp-009

No08-Pp-011

No08-Pp-012

No08-Pp-015

0,01 0,10 1,00 10,00 100,00

Rhizoctonia solani

No08-Rs-020

No08-Rs-025

No08-Rs-027

No08-Rs-130

No08-Rs-004

No08-Rs-011

No08-Rs-013

No08-Rs-014

No08-Rs-016

No08-Rs-019

Rizolex 50FW (Tolclofosmethyl) Lipid peroxidation, Aromatic Hydrocarbons,

FRAC Code F3

0,01 0,10 1,00 10,00 100,00

Rizolex 50 FW(Tolclophosmethyl in ppm )

No08-Cc-016

No08-Cc-037

No08-Cc-057

No08-Cc-10

No08-Cc-13

No08-Cc-19

No08-Cc-42

No08-Cc-43

No08-Cc-47

No08-Cc-50

0,01 0,10 1,00 10,00 100,00

No08-Hs-059

No08-Hs-060

No08-Hs-062

No08-Hs-067

No08-Hs-020

No08-Hs-021

No08-Hs-027

No08-Hs-029

No08-Hs-035

No08-Hs-041

0,01 0,10 1,00 10,00 100,00

No08-Pp-034

No08-Pp-043

No08-Pp-048

No08-Pp-053

No08-Pp-001

No08-Pp-005

No08-Pp-009

No08-Pp-011

No08-Pp-012

No08-Pp-015

0,01 0,10 1,00 10,00 100,00

Rhizoctonia solani

No08-Rs-020

No08-Rs-025

No08-Rs-027

No08-Rs-130

No08-Rs-004

No08-Rs-011

No08-Rs-013

No08-Rs-014

No08-Rs-016

No08-Rs-019

Maxim 100 FS(fludioxonil) Inhibition of osmotic signal transduction, phenylpyrroles,

FRAC Code E2

0,01 0,10 1,00 10,00 100,00

Maxim 100 FS (fludioxonil in ppm )

No08-Cc-016

No08-Cc-037

No08-Cc-057

No08-Cc-10

No08-Cc-13

No08-Cc-19

No08-Cc-42

No08-Cc-43

No08-Cc-47

No08-Cc-50

0,01 0,10 1,00 10,00 100,00

Maxim 100 FS (Fludioxonil in ppm )

No08-Hs-059

No08-Hs-060

No08-Hs-062

No08-Hs-067

No08-Hs-020

No08-Hs-021

No08-Hs-027

No08-Hs-029

No08-Hs-035

No08-Hs-041

0,01 0,10 1,00 10,00 100,00

No08-Pp-034

No08-Pp-043

No08-Pp-048

No08-Pp-053

No08-Pp-001

No08-Pp-005

No08-Pp-009

No08-Pp-011

No08-Pp-012

No08-Pp-015

0,01 0,10 1,00 10,00 100,00

Rhizoctonia solani

No08-Rs-020

No08-Rs-025

No08-Rs-027

No08-Rs-130

No08-Rs-004

No08-Rs-011

No08-Rs-013

No08-Rs-014

No08-Rs-016

No08-Rs-019

Emesto(Penflufen) Inhibition of respiration complex II, Succinate DeHydrogenase Inhibitors,

FRAC Code C2

0,01 0,10 1,00 10,00 100,00

BYF14182 (Penflufen in ppm )

No08-Cc-016

No08-Cc-037

No08-Cc-057

No08-Cc-10

No08-Cc-13

No08-Cc-19

No08-Cc-42

No08-Cc-43

No08-Cc-47

No08-Cc-50

0,01 0,10 1,00 10,00 100,00

No08-Hs-059

No08-Hs-060

No08-Hs-062

No08-Hs-067

No08-Hs-020

No08-Hs-021

No08-Hs-027

No08-Hs-029

No08-Hs-035

No08-Hs-041

0,01 0,10 1,00 10,00 100,00

No08-Pp-034

No08-Pp-043

No08-Pp-048

No08-Pp-053

No08-Pp-001

No08-Pp-005

No08-Pp-009

No08-Pp-011

No08-Pp-012

No08-Pp-015

0,01 0,10 1,00 10,00 100,00

Rhizoctonia solani

No08-Rs-020

No08-Rs-025

No08-Rs-027

No08-Rs-130

No08-Rs-004

No08-Rs-011

No08-Rs-013

No08-Rs-014

No08-Rs-016

No08-Rs-019

Fungazil(Imazalil) Inhibition of sterol biosynthesis in membranes, DeMethylation Inhibitors,

FRAC Code G1

0,01 0,10 1,00 10,00 100,00

Fungazil 100SL (Imazalil in ppm )

No08-Cc-016

No08-Cc-037

No08-Cc-057

No08-Cc-10

No08-Cc-13

No08-Cc-19

No08-Cc-42

No08-Cc-43

No08-Cc-47

No08-Cc-50

0,01 0,10 1,00 10,00 100,00

No08-Hs-059

No08-Hs-060

No08-Hs-062

No08-Hs-067

No08-Hs-020

No08-Hs-021

No08-Hs-027

No08-Hs-029

No08-Hs-035

No08-Hs-041

0,01 0,10 1,00 10,00 100,00

No08-Pp-034

No08-Pp-043

No08-Pp-048

No08-Pp-053

No08-Pp-001

No08-Pp-005

No08-Pp-009

No08-Pp-011

No08-Pp-012

No08-Pp-015

0,01 0,10 1,00 10,00 100,00

Fungazil (Imazalil in ppm )

Rhizoctonia solani

No08-Rs-020

No08-Rs-025

No08-Rs-027

No08-Rs-130

No08-Rs-004

No08-Rs-011

No08-Rs-013

No08-Rs-014

No08-Rs-016

No08-Rs-019

Proline EC250 (Protiokonazol) Inhibition of sterol biosynthesis in membranes, DeMethylation Inhibitors,

FRAC Code G1

0,01 0,10 1,00 10,00 100,00

Proline EC250 (Protiokonazol in ppm )

No08-Cc-016

No08-Cc-037

No08-Cc-057

No08-Cc-10

No08-Cc-13

No08-Cc-19

No08-Cc-42

No08-Cc-43

No08-Cc-47

No08-Cc-50

0,01 0,10 1,00 10,00 100,00

No08-Hs-059

No08-Hs-060

No08-Hs-062

No08-Hs-067

No08-Hs-020

No08-Hs-021

No08-Hs-027

No08-Hs-029

No08-Hs-035

No08-Hs-041

0,01 0,10 1,00 10,00 100,00

No08-Pp-034

No08-Pp-043

No08-Pp-048

No08-Pp-053

No08-Pp-001

No08-Pp-005

No08-Pp-009

No08-Pp-011

No08-Pp-012

No08-Pp-015

0,01 0,10 1,00 10,00 100,00

Rhizoctonia solani

No08-Rs-020

No08-Rs-025

No08-Rs-027

No08-Rs-130

No08-Rs-004

No08-Rs-011

No08-Rs-013

No08-Rs-014

No08-Rs-016

No08-Rs-019

Amistar (azoxystrobin) + Salicylhydroxamic acid Inhibition of respiration complex III, Quinone outside inhibitors

FRAC Code C3,

0,01 0,10 1,00 10,00 100,00

Amistar (Azoxystrobin in ppm )

No08-Cc-016

No08-Cc-037

No08-Cc-057

No08-Cc-10

No08-Cc-13

No08-Cc-19

No08-Cc-42

No08-Cc-43

No08-Cc-47

No08-Cc-50

0,01 0,10 1,00 10,00 100,00

No08-Hs-059

No08-Hs-060

No08-Hs-062

No08-Hs-067

No08-Hs-020

No08-Hs-021

No08-Hs-027

No08-Hs-029

No08-Hs-035

No08-Hs-041

0,01 0,10 1,00 10,00 100,00

No08-Pp-034

No08-Pp-043

No08-Pp-048

No08-Pp-053

No08-Pp-001

No08-Pp-005

No08-Pp-009

No08-Pp-011

No08-Pp-012

No08-Pp-015

0,01 0,10 1,00 10,00 100,00

Rhizoctonia solani

No08-Rs-020

No08-Rs-025

No08-Rs-027

No08-Rs-130

No08-Rs-004

No08-Rs-011

No08-Rs-013

No08-Rs-014

No08-Rs-016

No08-Rs-019

Application of seed treatment in

autumn or spring ?

The control had silver scurf on 50% of the plugs

and black scurf on 12 % of the plugs =>no

significant differenses between treatments for

black scurf.

Autumn Spring Autumn + spring

% control of silvers curf in progeny tubers

Imazalil sulfat

Fludioxonil

Copperoxide

Penflufen

Silver scurf, black scurf and dry rot · Silver scurf, black scurf and dry rot Ragnhild Nærstad...

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