Dr. Latorse, M.P, Jarry F., Mercier V., Veloso S.

Bologna Potato Workshop May 2-5 2007

Tuber blight control: effect of foliar applied fungicides such as Infinito on viability of sporangia of Phytophthora infestans

Bayer CropScience Research – Bologna Euroblight Slide 2

How to Control Tuber Blight ?

1) Reduction of sporulation

2) Spores + product are washedoff together:direct sporicide effect

3) Newly formed sporangia are affected in their viability :inoculum less infectious

Bayer CropScience Research – Bologna Euroblight Slide 3

In vitro sporangia germination test in aquaeousmedia

On planta sporangia infectivity test on foliar discs or tuber slices

Sporangia viability (vital staining)

Methods for Viability Evaluation

A rapid Live/dead viability test using fluorescent fluorochromes developed / validated

Bayer CropScience Research – Bologna Euroblight Slide 4

Live/ dead Viability Test Comparison

FDA fluoresces bright green in viable spores / PI fluoresces red-orange in non viable spores under blue light

Advantage / disavantage using FDA alone or in mixture Kit (FDA/PI)

- Live /dead viability Kit formulation stable for observation all day long // FDA alone

- PI is a potential mutagen: handle with appropriate caution

No significant differences detected between FDA alone and Kit (FDA+PI)Ratio Alive/dead sporangia depends on time of sporangia harvest in relation to beginning of sporulation and also links to the ability of products to reduce sporulation

Bayer CropScience Research – Bologna Euroblight Slide 5

Translaminar Activity (% infestation)

Strong translaminar activity of Infinito

Good translaminar effect of fluopicolide and dimethomorph with kinetic response

Rapid penetration of fenamidone

Quick penetration cymoxanil but short persistance due to quick metabolism

0

20

40

60

80

100

3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48

UTC

Infinito 1,2 L/ha

Infinito 1,4 L/ha

Infinito 1,6 L/ha

Shirlan 0,4 L/ha

Acrobat M 2 kg/ha

Fluopicolide 0.18 L eq 1,4 L/haInfinitoFluopicolide 0.2 L eq 1,6L/haInfinitoCurzate M 2kg/ha

Fenamidone 0.3 L eq 1,5kg/haSereno

% infestation

Time between treatment and inoculation

Bayer CropScience Research – Bologna Euroblight Slide 6

Translaminar Activity (% infestation)

Translaminar effect of fungicides with 24 h interval between preventive treatment and inoculation

0

20

40

60

80

100

UTC Fluopicolide0,16 L/ha (eq1.2 Infinito)

Fluopicolide0,18 L/ha (eq1.4 Infinito)

Fluopicolide 0,2L/ha (eq 1.6

Infinito)

Infinito 1,6 L/ha Shirlan Acrobat Fenamidone0,3 L/ha (eq 1.5Kg/ha Sereno)

% in

fest

atio

n

Fluopicolide translaminar activity with clear dose responseInfinito strong translaminar profile within 24 hours after treatment Sporangia for secondary infection could not be harvested for Infinito

Bayer CropScience Research – Bologna Euroblight Slide 7

Sporangia Viability by Vital Staining

Dead sporangia (%) by viable staining 7 days after inoculation ( 48h, preventative)

Contact fungicides do not influence the viability of newly formed sporangiaTranslaminar product such as fenamidone reduces viability of newlyformed sporangia

0

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40

60

80

100

Control Control 0.4 l/ha 2 kg/ha 1.5 kg/ha

Dead Alive fluazinam mancozeb Sereno

Bayer CropScience Research – Bologna Euroblight Slide 8

Sporangia Viability by Vital Staining

Reduction of viability by translaminar fungicides at curative applicationlower compared to preventativeInfinito provided significant reduction of spore viability

Dead sporangia (%) by viable staining 7 days after inoculation ( 48h, curative)

0

20

40

60

80

100

Control Control 0.4 l/ha 1.5 kg/ha 1.6 l/ha 1.6 l/ha

Dead Alive fluazinam Sereno fluopicolide Infinito

Bayer CropScience Research – Bologna Euroblight Slide 9

Anti-sporulant Activity :

Infinito has strong anti-sporulant properties

Sporulation index relative to untreated after curative application

Index (%)

0

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Control 1.2 l/ha 1.6 l/ha 2.0 l/ha 0,4 l/ha 2.14 kg/ha

Control Infinito Infinito Tattoo C fluazinam mancozeb

Bayer CropScience Research – Bologna Euroblight Slide 10

Infectivity Test (sporangia production)

Infinito reduces the infectivity of newly formed sporangia, coming fromthe reduction of sporangia both number and viability

Infectivity newly formed sporangia (spores / ml)

0

10000

20000

30000

Control 1.2 l/ha 1.6 l/ha 2.0 l/ha 2.14 kg/ha

0

20

40

60

80

100

Control 1.2 l/ha 1.6 l/ha 2.0 l/ha 0,4 l/ha 2.14 kg/ha

Anti-sporulant effect

Control Infinito Infinito Tattoo C mancozeb

Infinito Infinito

Bayer CropScience Research – Bologna Euroblight Slide 11

How to Control Tuber blight

Sporicide effect

Spore viability

Tuber blight control of Infinito based on multiple action

Spore quantity

Bayer CropScience Research – Bologna Euroblight Slide 12

Tuber Blight Control NL

Relative tuber blight infection (%)

0

20

40

60

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100

0.3 l/ha 0,4 l/ha 0.2 l/ha 1.2 l/ha 1.4 l/ha 1.6 l/ha

(relative % diseased tubers, average of 2 trials BCS Netherlands 2006)

InfinitoFluazinam InfinitoCyazofamidFluazinam Infinito

Bayer CropScience Research – Bologna Euroblight Slide 13

Conclusions / Recommendations

The live/dead viability kit ( FDA & PI) validated as a rapid indicator ofPhytophthora sporangia viabilityTranslaminar fungicides have potential to reduce sporulation according to their kinetics of penetration, bio availability and fungicidal properties

Infinito was confirmed as a strong translaminar and anti-sporulant fungicideInfinito has a multiple action:

– strong sporicide effect– reduction of sporulation– reduction of viability and infection success of sporangia

The properties of fungicides on apparent infection rates should be consideredfor incorporation into DSS to optimise late blight / tuber blight control

Thank you very much for your kind attention