Plant Breeding and Acclimatization Institute - RadzikówDEPARTMENT OF POTATO PROTECTION AND SEED SCIENCE – BONIN, POLAND

Józefa Kapsa & Edward Bernat

Effectiveness of some fungicides in controlof Alternaria alternata and Alternaria solani

EARLY BLIGHT - Alternaria species

The fungus was described for the first time in potato -late in the 19th century (Ellis & Martin, 1882)

Photo by G. Kleinschmidt.

Losses of the yield due to early blight

First information about losses: 10-32% (Neergaard 1945)

10-57% (Harrison et al. 1965)

SU - 25%, locally 60% (Bacanov 1970, Dorożkin 1972)

Average losses in USA 20-30% (Johnson et al. 1986, Fry 1994),

up to 50% Hadders (2002)

In Brazil losess up to 73% (Brune, et al. 1998)

In South Africa up to 50% (Denner & Theron 1999)

In Poland 10-32% (Kuczyńska 1992), 6-45% (Kapsa & Osowski 2004)

Factors affecting early blight development

Potato plants infected with some viruses are more susceptible to the early blight infection; this refers mainly to viruses PVY, PLRV and PVX

- Alternating wet/ dry periods- Wind borne spores- Factors influenced on plant weakness.

- senescing plants- soil with low contents of organic matter- low nitrogen fertilization- other pathogens’ infection

Fungal species/synonyms

Host plants

Disease symptoms

Optimum temperature -

0C*

Spore morphology**

Alternaria solaniMacrosporium solani

A.porri f.sp.solani

A.dauci f.sp.solani

plants from

SolanacewithoutDatura

Sporulation - temp. 26-280C

Mycelium growth & spore germination

– 18-220C

Alternaria alternataA.tenuisTorula alternata

about 40 plant

species

Sporulation - temp. 25-260C

Mycelium growth & spore germination

– 22-260CBrown leaf spot

Early blight

Source: * Dorozkin, Bel’skaja 1979** Hooker 1990

Characteristics of two Alternaria species, the casual agents of potato early blight

Materials and methods

Laboratory conditions: temp. 25°C, RH 90%– 10 Petri dishes / fungicide x 2 doses (field dose & 10 x lower)

Treatment Active substance Dose kg-l /haUntereated control - -Altima 500 SC fluazinam 0,4Amistar 250 SC azoxystrobin 1,0Antracol 70 WG propineb 1,8Ridomil Gold MZ 68 WG mefenoxam + mzb 2,0Infinito 678,5 SC fluopicolide+propamocarb-HCl 1,6Revus 250 SC mandipropamid 0,6Tanos 50 WG cymoxanil+famoxadone 0,5Dithane NeoTec 75 WG mancozeb 2,0Unikat 75 WG zoxamide + mzb 2,0

5 mm ø

Criteria of assesment

diameter of mycelium - mm

surface of mycelium - %

number of spores

Mycelium development of Alternaria spp. on artificial medium

0

20

40

60

80

100

120

0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21

d a y s

A.alternata A.solani

Influence of a fungicide supplementon development of mycelium growth

0

10

20

30

40

50

60

70

80

90

3 6 9 12 15 3 6 9 12 15 18 21

A.alternata A.solani

myc

eliu

m g

row

th -

mm

control

Altima 500 SC

Amistar 250 SC

Antracol 70 WG

Ridomil Gold MZ 68 WG

Infinito 687,5 SC

Revus 250 SC

Tanos 50 WG

Dithane NeoTec 75 WG

Unikat 75 WG

Influence of a fungicide supplementon size (diameter) of Alternaria spp. mycelium

0

10

20

30

40

50

60

70

80

90

Kontrola Altima 500 SC

Amistar 250 SC

Antracol 70 WG

Ridomil Gold MZ 68 WG

Infinito 687,5 SC

Revus 250 SC

Tanos 50 WG

Unikat 75 WG

LSD

A.alternata field dose A.alternata dose 10 x lowerA.solani field dose A.solani dose 10 x lower

mm

Influence of a fungicide supplementon the area of Alternaria spp. mycelium

0

10

20

30

40

50

60

70

80

90

100

Kontrola Altima 500SC

Amistar250 SC

Antracol70 WG

RidomilGold MZ68 WG

Infinito687,5 SC

Revus250 SC

Tanos 50WG

Unikat 75WG

LSD

A.alternata field dose A.alternata dose 10 x lowerA.solani field dose A.solani dose 10 x lower

%

Efficacy of fungicidesin inhibition of mycelium growh

79,1

40,5

75,5

49,2

100,

0

50,8

38,2

100,

0

75,6

37,6

63,1

50,1

65,9

54,1

14,4

100,

0

90,1

25,2

83,5

100,

0

60,6

100,

0

34,8

100,

0

84,6

26,1

76,2

100,

0

21,8

100,

0

14,5

100,

0

0

20

40

60

80

100

120

Altima 500SC

Amistar 250SC

Antracol 70WG

Ridomil GoldMZ 68 WG

Infinito 687,5SC

Revus 250SC

Tanos 50WG

Unikat 75WG

A.alternata field dose A.alternata dose 10 x lowerA.solani field dose A.solani dose 10 x lower

0,0

20,0

40,0

60,0

80,0

100,0

Altima 500 SC

Amistar 250 SC

Antracol 70 WG

Ridomil Gold MZ 68 WG

Infinito 687,5 SC

Revus 250 SC

Tanos 50 WG

Dithane NeoTec 75

WG

Unikat 75 WG

A.alternata A.solani%

Efficacy-% A. alternata A. solani

75,1 - 100

mancozeb; zoxamide+mzb; fluopicolide+propamocarb-HCl; fluazinam; propineb;

mancozeb; mandipropamid; mefenoxam+mzb; zoxamide+mzb; fluazinam; propineb;

50,1 -75,0 mandipropamid fluopicolide+propamocarb-HCl;

< 50,0mefenoxam+mzb; azoxystrobine; cymoxanil+famoxadone

cymoxanil+famoxadone; azoxystrobine

Fungicide effectiveness in inhibition of mycelium growth

Influence of a fungicide supplementon spore density

0

2

4

6

8

10

12

14

16

18

20

control Altima 500 SC

Amistar 250 SC

Antracol 70 WG

Ridomil Gold MZ 68 WG

Infinito 687,5 SC

Revus 250 SC

Tanos 50 WG

Unikat 75 WG

no of spores

A.alternataA.solani

Conclusionl Tested fungicides showed differences of efficacy in control

of two species of Alternaria fungus : A. alternata & A. solani

l Some of them inhibited growth of the both species at thesame level (mancozeb, zoxamide+mzb, cymoxanil+famoxadone*

l A few of fungicides showed better effectiveness in inhibitionof A.alternata (fluopicolide+propamocarb-HCl, azoxystrobine),

l Some of them were more effective against A. solani(mandipropamid, mefenoxam+mzb, fluazinam*, propineb*)