Mancozeb: essential tool for sustainable protection of potato

against late blight Serge Duvauchelle, consultant

Daniele Ruccia, UPL Euroblight, Brasov - May 2015

Introduction

Late blight epidemic • Example of Northern France / 2014

Late blight control: fungicides F: Lipid and membrane synthesis, cell wall F4 propamocarb F5 dimetomorph mandipropamid benthiavalicarb valifenalate

C: Respiration, mitochondria C3 famoxadone fenamidone C4 cyazofamid C5 fluazinam

MULTISITE mancozeb

Mitochondrion

Vacuole

Nucleus

Cytoplasmic membrane

A: Nucleic acid synthesis A1 metalaxyl-M benalaxyl

B: Mitosis and cell division B3 zoxamide B5 fluopicolide

Fungal cell

Mancozeb: 60 years of registration, multi-site mode of action, stable efficacy against early and late blight

Late blight population across Europe

Source: Euroblight 2013

Efficacy of mancozeb on different strains of

Phytophthora infestans Wageningen University, 2014

Tested strains

Strains Background Trial detached leaf

Trial pot in greenhouse

Blue 13 (13-A2)

Detected in NL and DE in 2004, in UK and FR in 2005, in Ireland in 2007, also present in many other EU countries since 2012. Strain more aggressive at low temperatures (8°C), resistant to phenylamides

Tested Tested

Green 33 (33_A2)

Detected in NL in 2011, also present in BE and PL. Fluazinam is less efficacious on this strain. Expresses a weak fitness, therefore regresses when fluazinam solo is not any more used in a systematic way. Represented more than 20% of the strains in 2010 and 2011 but only 6% in 2012

Tested Tested

Pink 6 (6_A1)

Detected in NL in 2002, in UK and FR in 2004. Seems very aggressive on leaf at temperatures around 10°C. Dominant in UK in 2011 and 2012, tends to regress during the last years

Tested Tested

Orange Old strain of A1 type, still present today but in a minority proportion Not tested Tested

Population VK98014 Old strain stored in the lab, supposed to be fully susceptible to fungicides Tested Not tested

Lab trials: objectives and methods • Evaluate the efficacy of mancozeb at 1500 g

ai/ha (Penncozeb®), in laboratory

• Late blight disease severity assessed 7 days after inoculation (incubated in climate chamber)

• Percentage necrotic foliage per leaf disc was determined

Lab trials: results

Type of strain Untreated % necrotic surface 7 days after inoculation

Mancozeb 1500 g/ha % necrotic surface 7 days after inoculation (efficacy)

Blue 13 99,8 17,3* (82,7) Green 33 96,8 2,5* (97,4) Pink 6 95,5 2,5* (97,4) VK 98074 91,2 2,5* (97,3) *: values statistically different from untreated at 5% threshold in the 2 trials

Greenhouse trial: objectives and methods • Evaluate the efficacy of mancozeb, fluazinam

and metalaxyl-M

• Cultivated potato plants (cv. Bintje) grown in 5 LT pots placed in greenhouse

• One month after planting, potato plants sprayed (250 l/ha) with the different fungicides in a spraying cabin

• Inoculum (10,000 sporangia/ml) carried out six days after spraying the fungicides. After inoculation, the potato plants were incubated in a climate chamber for one week

Greenhouse trial: protocol Code Fungicide Dose rate g ai / ha

A water (untreated control) -

B mancozeb 75% WG 1500

C mancozeb 64% + metalaxyl-M 8% WG 1600 + 200

D mancozeb 75% WG + fluazinam 500g/L SC 1500 + 200

E metalaxyl-M 25% WG 200

F fluazinam 500g/L SC 200

• Percentage necrotic foliage assessed 7, 9, 10, 13 and 15 days after inoculation. A Standard Area Under Disease Progress Curve (stAUDPC) was calculated.

• 4 replicates (1 replicate = 1 potato plant) • Analysis of variance based on the percentage of necrotic foliage

Greenhouse trial: results (1/2)

0

10

20

30

40

50

60

70

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100

7 10 15

Days after inoculation

water

metalaxyl-m

mancozeb

fluazinam

mancozeb + fluazinam

mancozeb + metalaxyl-m

Seve

rity

(%)

Example of disease curve: Pink 6

Greenhouse trial: results (2/2)

0

10

20

30

40

50

60

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water metalaxyl-m mancozeb fluazinam mancozeb +fluazinam

mancozeb +metalaxyl-m

blue 13 Green 33 Pink 6 orange

sAU

DPC

defg

j

h

hi i

k

bcd

fg

bcde

efg

ab ab

cdef

g

defg fg

abc

fg

bcd bcde

ab a a ab

Results (1/2) • The absence of control of Blue 13 by metalaxyl-m

confirms that this strain is metalaxyl-m resistant

• The efficacy of mancozeb (B) to control Blue 13 isolate was significantly better than fluazinam (F) and metalaxyl-m (E)

• Green 33 isolate was less effectively controlled by fluazinam (F) than mancozeb (B) and mancozeb + metalaxyl-m (C)

Results (2/2) • Pink 6 isolate was singnificantly better controled by

mancozeb (B), mancozeb + metalaxyl-m (C) and mancozeb + fluazinam (D) than fluazinam (F) or metalaxyl-m (E)

• Orange isolate was significantly better controlled with mancozeb + metalaxyl-m (C) than mancozeb (b) or metalaxyl-m

Conclusion • Mancozeb is effective against each type of strain • Its efficacy is less against Blue 13 isolate as a

consequence of high agressivity of this isolate • Mancozeb strenghens significantly the efficacy of

fluazinam and metalaxyl-m, even on strains sensitive to these fungicides

Stability of performance ensured whatever the type of strains met in the field

Essential for resistance management program

Next step • UPL has commissioned Wageningen University to

study the efficacy of mancozeb against Alternaria, especially against strains resistant to strobilurins

Regulatory Status

Mancozeb AIR3 timeline

Annex I inclusion 1st July 2006

Annex III Dossier submitted for Re-registration

by June 2008, evaluations completed from 2010 to 2013

Planned AIR submission

Jul 2015

AIR “Updating

statement” submission May 2013

Annex I Expiry

Date/Renewal 31st Jan 2018*

RMS UK CRD Meetings

Jan 13 & Mar 13, Q1 2014, Q1 2015

End 2009 AIR work started

Q4 2013 Task Force Toxicology work plan finalised with CRD, studies started Q1 2014

Product Re-registration Apr 2018

* Annex I expiry date extended by the European Commission, no longer 2016

Regulatory hurdles (1/2)

• R63/H361d (possible harm to the unborn child) classification based on European Chemicals Agency (ECHA) evaluation on public literature in 2006 showing ED effects at unrealistic high concentrations

• Interim Criteria: Reproductive Category 2 + “toxic” effects on endocrine organs may be considered to have ED properties – as a result of classification

Regulatory hurdles (2/2)

• ETU, a metabolite of mancozeb has been shown to affect the T3/T4 hormones in rats when dosed at very unrealistic high concentrations in public literature resulting in a R63/H361d classification

• Effects seen in the rat are not relevant to humans due to well known differences in physiology. When dosed at realistic exposure concentration – New data shows that there is NO ADVERSE EFFECT

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MANCOZEB

EU Mancozeb Task Force coordinator Name: Mrs Barnali James Tel: +44 (0) 1925 859006 Email: bgoswami@uniphos.com

Contact Details