Control of early blight by the use of SDHI Fungicides · 2018. 9. 19. · (master´s thesis, Metz) 2 . ... Occurrence of SDH-mutated A. solani isolates 2016 . 3 . 325 isolates, 26

Technische Universität München

Control of early blight by the use of SDHI Fungicides

Nicole Metz

PhD project TUM School of Life Science Weihenstephan

Technical University Munich Chair of Phytopathology

Chair leader: Prof. Dr. Ralph Hückelhoven


Background

• Alternaria solani (causes early blight) is getting more relevant for the farmers in Germany (Leiminger, J. H.; Hausladen, H.; 2011)

-> yield losses of more than 50% are possible

• High development of resistance against strobilurines (QoI´s) (Leiminger, Hausladen, Adolf,

2014) and carboxamides (SDHI´s) (Gudmestad et al., 2012; Landschoot et al., 2016)

• EC50 values and greenhouse trials were already performed (bachelor´s thesis N. Chaluppa)

• Inducing a consistent infection with A. solani in the field with the kernel infection was successful for a mixture of different A. solani isolates (master´s thesis, Metz)

2


Occurrence of SDH-mutated A. solani isolates 2016

3

325 isolates,

26 locations

mutants in all loc.


Main research questions

• Is there a decreasing efficacy of SDHI-fungicides to Alternaria solani in vitro, in

vivo and in the field?

• Is it necessary to test all three stages of sensitivity-testing to get deeper knowledge about the pathogen, its epidemiology and the resistance development against fungicides?

• Is the kernel infection a possibility for targeted infection with single A. solani

isolates in the field? → 3 different isolates (2xSDH mutants (H134R), 1xSDH wildtype)

4


In vivo (Boscalid) – Methods

• Different treatments with Boscalid (0,1; 1,0; 10; 100µg/ml and control) one day

before inoculation

• Inoculation with spore solution of single

A. solani isolates (mutants and wildtyps)

• After inoculation 48 h in the mist chamber

at 100% RH and 20°C

• Afterwards about 70% RH

• Rating of the plants: 2 and 7 dai

8


0,00

50,00

100,00

WT SDH mutant

Fung

icid

e-ef

ficac

y (%

)

A. solani isolates

In vivo (Boscalid 100µg/ml) – Results

6

Inoculation with mutated A. solani isolates compared to wildtypes leads to a decreasing efficacy of Boscalid in greenhouse trials


0

50

100

599 615 708_2 626 699 555 561 628 687_1

Wildtype B-H278R C-H134Q C-H134R

Effic

acy

for 1

00µg

bos

calid

/ml (

%)

A. solani isolates

In vivo (100 µg boscalid/ml) – Results

N. Chaluppa, 2016

7


Trial setup for the fungicide-test in the field

• Plot size: 4 x 4,5 m

• Varieties: Maxilla (susceptible, late maturity group) Lady Amarilla (very susceptible, early maturity group) • Treatments: 4 different active ingredients + untreated control

• Inoculation: 3 different A. solani isolates with infected kernels

+ untreated control

8


Kernel infection

• Cultivation of the A. solani isolates on SNA-agar plates

• Mixing half of the overgrown plate in bags with 150 g kernels

• Storing the bags for four weeks under UV-light (12h/12h)

• Putting out the infected kernels between the potato rows (5 g per m²)

9


Tested active ingredients

• SDHI 1

• SDHI 2

• SDHI 3

• SDHI 4

• Application in a 14 day interval with a backpack sprayer

10


Results Lady Amarilla with SDH-wildtype 615

Control SDHI 1 SDHI 2

23.08.16 23.08.16 23.08.16

0

0,2

0,4

0,6

control SDHI 1 SDHI 2 SDHI 3 SDHI 4

Inoculum: SDH-wildtype 615, variety: Lady Amarilla

rAU

DP

C

control and fungicides

a

b

c d

e

All fungicides lead to a reduced early blight infection in the wildtype-inoculation

11


Results Lady Amarilla with SDH-mutant 628


23.08.16 23.08.16 23.08.16

0

0,2

0,4

0,6


Inoculum: SDH-mutant 628, variety: Lady Amarilla

rAU

DP

C


a

b b c

d

All fungicides lead to a reduced early blight infection in the first mutant-inoculation

12


Results Lady Amarilla with SDH-mutant 687_1

0

0,2

0,4

0,6


Inoculum: SDH-mutant 687_1, variety: Lady Amarilla

rAU

DP

C


a a a a a

High loss of efficacy for all fungicides in the second mutant-inoculation

13


Results Maxilla with SDH-mutant 687_1

0

0,1

0,2

0,3

0,4


Inoculum: SDH-mutant 687_1, variety: Maxilla

rAU

DP

C


a a a a

b

01.09.2016 01.09.2016 01.09.2016


High loss of efficacy for all fungicides without one SDHI in the second mutant-inoculation

14


Further fungicide-results, variety Maxilla

0,0

0,1

0,2

0,3

0,4


Inoculum: SDH-mutant 628, Variety: Maxilla

rAU

DPC

(exc

ludi

ng b

orde

r plo

ts)


a b

c b

b

0

0,1

0,2

0,3

0,4


Inoculum: SDH-wildtype 615, variety: MaxillarA

UD

PC


a c

b bc

a

All fungicides lead to a reduced early blight infection in the first mutant -and in the wildtype inoculation (without one)

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Results - Summary

Decreasing fungicide efficacy in vivo (Boscalid) regarding the spray inoculation with several SDH-mutated isolates

Decreasing fungicide efficacy in the field trial

Differences between the two mutants which were used in the field-trial (although they have the same mutation H134R)

The variety (and/or the maturity group) still plays an important role in integrated pest management

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Conclusion

All three stages of sensitivity testing give a deeper knowledge about the raising loss of sensitivity and the hole pathogen Ways to slow down the resistance development are necessary, regarding the integrated pest management Other ways to control early blight are also important to analyze (e.g. Biologicals, plant ingredients)

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Outlook

Retesting the EC50-values Testing more isolates in greenhouse trials Repetition of the first field trial Testing a combination of biologicals and fungicides in a field trial …. Some other ideas are in progress

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Thank you very much for your attention!

19

Documents

Control of early blight by the use of SDHI Fungicides · 2018. 9. 19. · (master´s thesis, Metz) 2 . ... Occurrence of SDH-mutated A. solani isolates 2016 . 3 . 325 isolates, 26