Effect of Climate Change onEffect of Climate Change on Potato Diseases and Pests in South Africa

Jacquie van der Waals, Kerstin Krüger, Linus Franke, Anton Haverkort, Martin Steyn

EAPR 2013, Jerusalem

INTRODUCTION

Disease Pyramidy

PathogenPathogenGrower

Time

Disease

Host EnvironmentHost Environment

Late blightSoft rot and blacklegg

Myzus persicae

Root knot

(PVY and PLRV)

Root-knot nematodes

Early blight and brown spot

MATERIALS AND METHODSMETHODS

Disease development rulesDisease development rules

• For each organism a set of “rules” was drawn up• For each organism a set of rules was drawn up using literature to describe conditions for disease development or population growth: defined asdevelopment or population growth: defined as cumulative relative development rate (cRDR)

• Parameters used: min opt max temperature;• Parameters used: min, opt, max temperature; relative humidity

• Indication of change in disease pressure over• Indication of change in disease pressure over period 1961 - 2050

• High resolution climate models were used to• High resolution climate models were used to calculate daily weather data (maximum and minimum temperatures precipitation wind speedminimum temperatures, precipitation, wind speed and solar radiation) for the period 1961 – 2050

Hectares per Production RegionLimpopo

Loskop Valley

Dry winter≈ 2m tonnes produced annually on about

Mpumalanga

North West Gauteng

annually on about 60 000 ha

Eastern FS

KZNWet summer

Western FS

Northern Cape

South West FS

Eastern Cape

North Eastern Cape

Sandveld

Ceres

Southern Cape

Wet winterDry summer

Southern CapeSouth West Cape

B. Pieterse, 2009

RESULTS AND DISCUSSIONDISCUSSION

Shifts in planting timesShifts in planting times(Franke et al., 2013)

• Sandveld: Current peak plantings of August-September are likely to shift a month earlier to July-August; the autumn plantings remain unchanged

• EFS: October-November plantings will probably also move forward to September-October

• Limpopo: Main planting starts in May and continues through winter until July with the peakcontinues through winter until July, with the peak planting period in June. By 2050 planting likely to start earlier in April-Maystart earlier in April May

Hectares per Production RegionLimpopo

Loskop Valley

Dry winter

Mpumalanga

North West Gauteng

Eastern FS

KZNWet summer

Western FS

Northern Cape

South West FS

Eastern Cape

North Eastern Cape

Sandveld

Ceres

Southern Cape

Wet winterDry summer

Southern CapeSouth West Cape

B. Pieterse, 2009

Late BlightLate Blight

10˚C > Temp. < 26˚Cd RH 75% f t ti dand RH >75% for two consecutive days

(Beaumont 1947; Krause et al. 1975; MacKenzie 1981; Zwankhuizen & Zadoks 2002)

30 Late blight EFSb30

Late blight Sandvelda

15

20

25

ativ

e RD

R

15

20

25

ativ

e RD

R

5

10Cum

ula

5

10

Cum

ula

0

Planting month

0

Planting month

25

30

R

Late blight LimpopocCumulative relative development rates (cRDR) of late blight on potatoes for the periods

10

15

20

Cum

ulat

ive

RDR potatoes for the periods

1961-1970 (······), 2001-2010 (—–) and 2041 2050 ( ) in

0

5

C 2041-2050 (----) in (a) the Sandveld, (b) the Eastern Free State and(c) Limpopo growing regions in SA

Planting month(c) Limpopo growing regions in SA

Early Blight and Brown SpotEarly Blight and Brown Spot“I f ti d ”“Infection day” =

10˚C > Temp. < 35˚Cd RH 75%and RH >75%(Rotem 1974)

70Early blight and brown spot Sandvelda

70

Early blight and brown spot EFSb

40

50

60

tive

RDR

40

50

60

tive

RDR

10

20

30

Cum

ula

0

10

20

30

Cum

ulat

0

Planting month

0

Planting month

60

70

R

Early blight & brown spot LimpopocCumulative relative development rates (cRDR) of early blight and brown spot on potatoes for the

20

30

40

50

Cum

ulat

ive

RDR brown spot on potatoes for the

periods 1961-1970 (······), 2001 2010 ( ) and

0

10

20C 2001-2010 (—–) and 2041-2050 (----) in (a) the Sandveld, (b) the Eastern Free State and

Planting month(b) the Eastern Free State and(c) Limpopo growing regions in SA

Soft Rot and BlacklegSoft Rot and BlacklegRDR 1 if A d il t 26˚CRDR = 1 if Ave daily temp = 26˚C

RDR = if Ave daily temp < 4˚C or > 37˚CIntermediate RDR values obtained through linearIntermediate RDR values obtained through linear

interpolation of values from 4-37˚CAir temp averages used as indication of prevalent soil

temps: (Tsoil = (Tmax + Tmin)/2)Soils are irrigated

(Duarte et al 2004; du Raan In Prep )(Duarte et al. 2004; du Raan In Prep.)

90

Pcb Sandvelda90

Pcb EFSb

50

60

70

80

ive

RDR

50

60

70

80

ve R

DR

10

20

30

40

Cum

ulat

i

10

20

30

40

Cum

ulat

i

0

Planting month

0

Planting month

80

90

Pcb Limpopoc Cumulative relative development rates (cRDR) of soft rot and blackleg on potatoes for the periods

40

50

60

70

mul

ativ

e RD

R

blackleg on potatoes for the periods 1961-1970 (······), 2001-2010 (—–) and 2041 2050 ( ) in

0

10

20

30

Cum 2041-2050 (----) in

(a) the Sandveld, (b) the Eastern Free State and(c) Limpopo growing regions in SA

Planting month

(c) Limpopo growing regions in SA

Root Knot NematodesRoot Knot NematodesRDR t d il t f 26 °C 1/25 0 04RDR at ave daily temp of 26 °C=1/25=0.04RDR = 0 if ave daily temp < 9.5˚C or > 34˚C

Intermediate RDR values obtained through linearIntermediate RDR values obtained through linear interpolation of values from 9.5-34˚C

Air temp averages used as indication of prevalent soil temps: (Tsoil = (Tmax + Tmin)/2)

Soils are irrigated(Vrain et al 1978; Ploeg & Maris 1999)(Vrain et al. 1978; Ploeg & Maris 1999)

3.5

RKN Sandvelda3.5

RKN EFSb

2

2.5

3

tive

RDR

2

2.5

3

tive

RDR

0.5

1

1.5

Cum

ulat

0.5

1

1.5

Cum

ula

0

Planting month

0

Planting month

3

3.5

RKN LimpopocCumulative relative development rates (cRDR) of root-knot nematodes for the periods

1.5

2

2.5

mul

ativ

e RD

R nematodes for the periods 1961-1970 (······), 2001-2010 (—–) and 2041 2050 ( ) in

0

0.5

1Cu

2041-2050 (----) in (a) the Sandveld, (b) the Eastern Free State and(c) Limpopo growing regions in SA

Planting month

(c) Limpopo growing regions in SA

Aphids as Vectors of PVYAphids as Vectors of PVYO ti l RDR i 1/1 95 0 51 t 26 7°COptimal RDR is 1/1.95=0.51 at 26.7°C.

Linear interpolation used to determine doubling timeRDR = 0 if daily min temp < 6 5°C or max > 37 3°CRDR 0 if daily min temp < 6.5 C or max > 37.3 C

(Bale et al., 2002; Davis et al. 2006)

45

Aphids Sandvelda45

Aphids EFSb

25

30

35

40

45

ve R

DR

25

30

35

40

ve R

DR

5

10

15

20

25

Cum

ulat

iv

5

10

15

20

Cum

ulat

iv

0

Planting month

0

5

Planting month

40

45Aphids Limpopoc Cumulative relative development

rates (cRDR) of aphids on potatoes for the periods

20

25

30

35

mul

ativ

e RD

R

for the periods 1961-1970 (······), 2001-2010 (—–) and 2041 2050 ( ) in

0

5

10

15

Cum 2041-2050 (----) in

(a) the Sandveld, (b) the Eastern Free State and(c) Limpopo growing regions in SA

Planting month

(c) Limpopo growing regions in SA

CONCLUSIONS

•Predictions can be made on how frequentlyq yparticular weather patterns will occur until20502050

Shift i l ti ti i ht ll•Shifts in planting times might allow escapefrom pathogens or pests

•Changes in climate are gradual – enoughg g gtime to alter management practices

• Published as: van der Waals et al. (2013) Potato Research 56:67-84

ACKNOWLEDGEMENTSACKNOWLEDGEMENTS

Funding:N h l d Mi i f E A i l• Netherlands Ministry of Economy, Agriculture and InnovationP t t S th Af i• Potatoes South Africa

• THRIP

Second announcement of the

2ND INTERNATIONAL POWDERY SCAB WORKSHOP

29 July – 1 August 2014

S th Af i (Kl i K ib Li P i )South Africa (Klein Kariba, Limpopo Province)

For more information email

jacquie vdwaals@up ac zajacquie.vdwaals@up.ac.za