FUNGICIDE

Isofetamid
New chemical class of SDHI
Isofetamid is a novel SDHI (Succinate Dehydrogenase Inhibitor, FRAC code 7)
fungicide discovered and under development by ISK.
Isofetamid is a new chemical group (phenyl-oxo-ethyl thiophene amide)
based on its thiophene carboxamide moiety. Due to this unique chemicalstructure, Isofetamid remains highly effective against the majority of fungal
isolates that have developed resistance to other SDHI fungicides.
As a broad-spectrum fungicide, Isofetamid exhibits excellent activity against
a broad range of fungi, but is especially effective on the Ascomycota (such asBotrytis spp., Sclerotinia spp., Monilinia spp., Venturia spp.) at low dose rates.
In addition to its outstanding efficacy, Isofetamid has no negative impacts
on beneficial insects and mites, making it an excellent choice for integrated
pest management programs.

Physico-Chemical Properties
Chemical structure

Toxicology & Ecotoxicology
CH3

HN

CH3
H3C
H3C

H3C

O

O

Rat LD50 (oral) : > 2,000 mg/kg (f)Rat LD50 (dermal) : > 2,000 mg/kg (m/f)
Rat LC50 (inhalation) : > 4.82 mg/L (m/f)

SCH3 O

Skin irritation : non irritant (rabbit)
Eye irritation : slightly irritating to eyes (rabbit)
Skin sensitization : not a sensitizer (mouse, guinea pig)

Class : Phenyl-oxo-ethyl thiophene amide
IUPAC name : N-[1,1-dimethyl-2-(4-isopropoxy-otolyl)-2-oxoethyl]-3-methylthiophene2-carboxamide
Molecular weight : 359.48
Molecular formula : C20H25NO3S
Vapour pressure : 4.2 x 10-7 Pa (25°C)
Water solubility : 5.33 mg/L (20°C)
Form : White Solid (powder)
Development code : IKF-5411Avian LD50 (acute oral) : > 2,000 mg/kg (quail, m/f)
Avian LD50 (subacute oral) : > 5,000 ppm in feed (quail)
Fish LC50 : > 7.12 mg/L (carp, 96 h)
Bees LD50 (acute oral) : > 30 μg a.i./bee (48 h)
Bees LD50 (acute contact) : > 100 μg a.i./bee (48 h)
Daphnia magna EC50 : 4.7 mg/L (48 h)

Product
Trade Names

KENJA, ZENBY, KRYOR, HAREGI, KABUTO, ASTUN, etc.

Formulations

40%SC

Registered Countries

AsiaChina, Japan, Korea

EuropeBelgium, Bulgaria, Czech Republic, France, Germany, Greece, Hungary, Italy, Luxembourg,Poland, Portugal, Romania, Spain, Slovenia, UK, etc.

Oceania

Australia

AmericasBrazil, Canada, Chile, Colombia, Ecuador, Mexico, Peru, USA, etc.

Always read and follow the product label instructions in your country.

Characteristics
・SDHI class (FRAC code 7) with broad-spectrum fungicidal activity

・Good persistence and rainfastness

・Flexible molecular structure makes it effective on major SDHI resistant isolates

・Extension of shelf life by pre-harvest application

・Inhibits all growth stages of fungal life cycle

・High safety for crop and beneficial organisms

ISHIHARA SANGYO KAISHA, LTD.

URL : http://www.iskweb.co.jp

E-mail : isk.bio@iskweb.co.jp

1-3-15 Edobori, Nishi-ku, Osaka 550-0002 TEL +81-6-6444-7154

Isofetamid

FUNGICIDENew chemical class of SDHI

Mode of Action
Isofetamid acts specifically on the succinate dehydrogenase (SDH) of Complex II, a key enzyme of themitochondrial respiratory chain at the crossroads of two metabolic pathways essential to fungal cell life.
By inhibiting SDH, Isofetamid impairs energy (ATP) production by the respiratory chain and the synthesis ofamino acids, lipids and fatty acids (metabolites essential to cell function) at the Krebs cycle stage.

IsofetamidBinding site

Advantages of Isofetamid for resistance management
Isofetamid can control numerous isolates with confirmed resistance to other SDHI fungicides, including SdhB
H272R and H272Y, which are the two most common field-collected isolates.
Research has confirmed that Isofetamid fits the mutated binding pocket of SDHI-resistant fungal isolates (SdhB
H272R and H272Y). It is hypothesized that the unique molecular structure of Isofetamid gives the molecule
flexibility at the binding site, allowing Isofetamid to retain efficacy on these mutants. Other SDHI fungicides havea rigid structure, are unable to bind at sites where mutations have occurred, and are therefore ineffective ascontrol options.
Isofetamid

OO

Isofetamid

S
N
H
Other SDHIs

O

Unique structure“Flexible bond”

ON
H“Rigid bond”

SDHI A

SDHI B

SDHI CSDHI DStandardS

S

S

S

S

SdhB H272Y

S

R

S

MR

R

SdhB H272R

S

R

S

S

S

SdhB N230I

S

R

MR

MR

R

SdhB P225F

R

R

R

R

R

SdhB H272L

RRRMR

R

S:Sensitive, MR:Moderately Resistant, R: ResistantFungicidal spectrum

Stable control against Gray mold (Grape field trials in EU)
Cercospora spp.

60

Monilinia spp.

Mycosphaerella spp.

50

Sclerotinia spp.

Passalora spp.

Venturia spp.

Pseudocercospora spp.

Corynespora spp.

Elsinoë spp.

Didymella spp.

Ramularia spp.

Wilsonomyces spp.

Alternaria spp.

Cladosporium spp.

Rhizopus spp.

Diaporthe spp.

and Powdery mildew

Disease severity (%)

Botrytis spp.

After Isofetamid applicationsin the field, fruit were collected
the next day and stored ontrays at room temperature.
Postharvest disease incidence
was evaluated 7days afterharvest.

2013
2017

30
200
Untreatedcontrol

Isofetamid
600 g a.i./haDisease name

Isofetamid
Botrytis sp.
Rhizopus sp.

Isofetamid 387 g a.i./ha
SDHI A+Qol A 626 g a.i./ha
SDHI B 286 g a.i./ha40

ISHIHARA SANGYO KAISHA, LTD.

Standard A
750 g a.i./haMultiple disease control (Cucumber field trials in Japan)

Untreated control

2030
Disease incidence (%)

2012
2016

40etc.

Untreated102011
2014
2020

10Control of fruit rots on strawberries during storage

0

Simulation modeling of enzyme
3D structure

Commercial
standard

Disease Incidence or Severity (％)
Isofetamid
266 ppm

Standard

Untreated
control

Sclerotinia rot
Sclerotinia sclerotiorum

Dicarboximides
250 ppm

1.4

0.5

44.5

Gray mold
Botrytis cinerea

Anilino-pyrimidines
200 ppm

0.2

1.634.4

Gummy stem blight
Didymella bryoniae

Dicarboximides
500 ppm

0.3

0.4

16.8

Corynespora leaf spot
Corynespora cassiicola

TPN
400 ppm

0.9

2.4

11.7

Powdery mildew
Podosphaera xanthii

Quinoxaline
83 ppm

0.5

6.764.5

URL : http://www.iskweb.co.jp

E-mail : isk.bio@iskweb.co.jp

1-3-15 Edobori, Nishi-ku, Osaka 550-0002 TEL +81-6-6444-7154