CA Presentation - B. Jv Rensburg | Mahlathini Development Foundation

The impact of conservation agriculture on

maize ear rots and resultant mycotoxin

production in commercial and smallholder

farming systems

MTM 19/03

Dr.Belinda Jansevan Rensburg

BelindaJ@arc.agric.za

Background

•Does an increase in residue cause an increase in disease and

mycotoxins?

•Crop rotation is crucial, however maize residues take longer to

decompose

- harbor Fusarium and other ear rot pathogens much longer

•2019/20 – 2022/23

Aim

•Todeterminetheeffect

of agricultural cropping

systemsonmaize earrot

infection and mycotoxin

contaminationindiverse

production areas

(commercial and

smallholder farmers)

Where doesthefungicome from that produce

mycotoxins?

The Disease Triangle

PATHOGEN

Total of virulence, abundance, etc.

ENVIRONMENT

Total of conditions favouring disease.

Total of conditions favouring susceptibility.

HOST

Fusariumverticillioides/ F. proliferatum

-FB1, FB2, FB3

-Funguscanpresent intheseed

-Infect roots, stalks, ears (susceptible from flowering stage)

-Hot, dry weather conducive for infection (28-32 °C)

Fusariumgraminearum spp. complex

-DON, NIV, ZEA

-Funguscanpresent intheseed

-Infect roots, stalks, ears (susceptible from flowering stage)

-Hot, wet weather conducive for infection (25-32 °C)

Stenocarpellamaydis

-Diplodiatoxin, Dipmatol

-diplodiosis, a neuromycotoxicosisof cattle and sheep

-Maize is the only host

-Start at the base of the maize ear, grow upward

-Late season rains, “skelm” Diplodia

M.G. Masango, B.C. Flett, C.E. Ellisand C.J. Botha.Stenocarpellamaydisand its toxic metabolites: a South African perspective on

diplodiosis. World Mycotoxin Journal, 2015; 8 (3): 341-350 WageningenAcademic Publishers.

Whymust we managemycotoxins?

•Affect the entire food and feed production chain.

•Reductionofmarketablegrain,increasedcostofdrying, decreasedweight

gaininanimalfeeding,fertilityproblems,andincreasedcostsforanimal

and human health.

•Restrictmarkets(fordevelopingcountries)

Materials and Methods

•Commercial farmers (2019/20 – 2022/23)

•Ottosdal, Kroonstad, Makwassie, Reitz

•56 samples collected before harvest

- different CA farming practices

•GPS – Fields area measure app

•Smallholder farmers (2019/20 – 2022/23)

•Bergville, Southern KZN, Midlands

•77 samples collected before harvest

- different CA farming practices

•individual samples sent to SAGL for multi –mycotoxin analyses

•Milled samples – DNA extractions, qPCR

Results– Commercial farmers

Table 1: Experimentaldesignincludingmaizemonoculture,croprotations,twodifferentrowwidthsand

plantdensities,repeatedthreetimesover a three-yeartimeperiod (Ottosdaltrialonly).

Maize50=rowwidth50cmandplantdensity =40 000ha-1

2018

/19

2019

/20

2020

/21

2021

/22

Block

1

Maize

50*

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Sunflower

Cover

crop

Maize

50

Maize

90

Cover

crop

Maize

50

Maize

90

Sunflower

Cover

crop

Block

2

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Sunflower

Cover

crop

Maize

50

Maize

90

Cover

crop

Maize

50

Maize

90

Sunflower

Cover

crop

Block

3

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Maize

50

Maize

90

Sunflower

Cover

crop

Maize

50

Maize

90

Cover

crop

Maize

50

Maize

90

Sunflower

Cover

crop

Locality

Crop system

Cultivation

Season

qPCR F. verticillioides (pg)/20µl

qPCR F. graminearum (pg)/20µl

Aflatoxin ppb (µg/kg)

Fumonisin ppb (µg/kg)

Deoxynivalenol ppb (µg/kg)

15

-Acetyl-DON ppb (µg/kg)

Ochratoxin A ppb (µg/kg)

Zearelanone ppb (µg/kg)

T2 ppb (µg/kg)

HT

-2 ppb (µg/kg)

Diplodia toxin ppb (µg/kg)

Kroonstad

(northern

Free State

Province)

Fallow

M

-Maize

(control)

M

-Maize

(control)

M

-Maize

(control)

Rip on row

Sandy soil

2018/2019

2019/2020

2020/2021

2021/2022

40

45

4

430

1364

7.36

ND

101

24

410

1604

211

103

139

ND

54

ND

247

Kroonstad

Sorghum

as cover

crop

Maize

Rip on row

Sandy soil

2018/2019

2019/2020

2020/2021

2021/2022

53

22

58

375

99

56.9

ND

27

ND

509

ND

<LOQ

ND

31

ND

90

Kroonstad

Intercrop,

soybeans

and maize

Intercrop,

soybeans

and maize

Rip on row

Sandy soil

2020/2021

2021/2022

89

16

78

148

ND

844

ND

157

ND

Kroonstad mean values

40.87

319.78

0

19

447.25

49.88

0

10.62

0

42.13

Locality

Crop system

Cultivation

Season

qPCR F. verticillioides

(

pg)/20µl

qPCR F.

graminearum

(

pg)/20µl

Aflatoxin ppb (µg/kg)

Fumonisin

ppb (µg/kg)

Deoxynivalenol ppb

(µg/kg)

15

-Acetyl-DON ppb

(µg/kg)

Ochratoxin A ppb (µg/kg)

Zearelanone

ppb (µg/kg)

T2 ppb (µg/kg)

HT

-2 ppb (µg/kg)

Diplodia

toxin ppb

(µg/kg)

Makwassie

(North

-West

Province)

M

-maize

(control)

M

-maize

(control)

Rip on row

Sandy soil

2019/2020

2020/2021

43

27

931

408

ND

1020

138

119

ND

Makwassie

Fallow

Maize

Rip on row

Sandy soil

2018/2019

2019/2020

2020/2021

2021/2022

544

25

61

6455

365

51

ND

682

307

55

7144

ND

345

ND

26193

ND

303

Makwassie

Ground

-

nuts

Maize

Soya

Maize

Rip on row

Sandy soil

2018/2019

2019/2020

2020/2021

2021/2022

101

100

881

ND

373

9619

2035

1042

266

ND

71

37

ND

84

Makwassie

Sunflower

Maize

Rip on row

Sandy soil

2019/2020

2020/2021

5

27

ND

Makwassie mean values

113.25

1302

0

177.13

2494.5

221.5

0

3287.63

0

48.38

Locality

Crop system

Cultivation

Season

qPCR F. verticillioides

(

pg)/20µl

qPCR F.

graminearum

(

pg)/20µl

Aflatoxin ppb (µg/kg)

Fumonisin

ppb (µg/kg)

Deoxynivalenol ppb

(µg/kg)

15

-Acetyl-DON ppb

(µg/kg)

Ochratoxin A ppb (µg/kg)

Zearelanone

ppb (µg/kg)

T2 ppb (µg/kg)

HT

-2 ppb (µg/kg)

Diplodia

toxin ppb

(µg/kg)

Reitz

(eastern Free

State

Province)

M

-Maize

M

-Maize

(control)

No

-till

Hattingh

50cm rw

2018/2019

2019/2020

45.3

458

ND

22

736

119

ND

34

ND

Reitz

Mixed seed

for cattle

grazing

Maize

No

-till

Hattingh

50 cm

rw

2018/2019

2019/2020

2020/2021

70

2.15

129

51

ND

93

Reitz

Sunflower

Maize

No

-till

Hattingh

50 cm rw

2018/2019

2019/2020

2020/2021

2021/2022

ND

14

0.56

64.4

30.2

9.15

ND

<LOQ

ND

72

Reitz

Soya

Maize

No

-till

Hattingh

50 cm rw

2019/2020

2020/2021

2021/2022

1.98

1.96

2.54

4.28

ND

Reitz mean values

16.99

93.57

0

2.75

92

14.87

0

4.25

0

20.63

Mean F.verticillioidesand F.graminearumlevels

(pg/20µl) measured from maize grain from three

different cropping systems over a three year period

-400

-200

0

200

400

600

800

1000

1200

M-Maize Soybe an /MaizeSunflowe r/Ma iz e

Target DNA (pg)/20µl)

qPCR F. verticillioides

qPCR F. graminearum

-500

0

500

1000

1500

2000

2500

3000

Aflatox in

Fumonisin

De o xyn ival en o l

15-Acetyl-DON

Ochratoxin A

Ze ar elan on e

T2

HT -2

Diplodia toxin

Mycotoxins in part per billion (µg/kg)

M-Maize Soybe an /MaizeSunflowe r/Ma iz e

Mean mycotoxin (ppb) measured from maize grain from different

cropping systems over a three year period

Results– Smallholder farmers

Farmer /

Locality

Crop system

Cultivation

Season

qPCR

F.

verticillioides

(pg)/20µl

qPCR

F.

graminearum

(pg)/20µl

Aflatoxin ppb

(µg/kg)

Fumonisin

ppb (µg/kg)

Deoxynivalen

ol ppb (µg/kg)

15

-Acetyl-

DON ppb

(µg/kg)

Ochratoxin A

ppb (µg/kg)

Zearelanone

ppb (µg/kg)

T2 ppb

(µg/kg)

HT

-2 ppb

(µg/kg)

Diplodia toxin

ppb (µg/kg)

Babhekele Nene

(Bergville

-

Mayizekane)

M

-Maize

(control)

No

-till

2019/2020

2020/2021

2021/2022

ND

78

125

1126

358

1987

ND

168

ND

354

25

18517

ND

80

ND

Babhekele Nene

Maize

–

Bean

intercrop

No

-till

2019/2020

2020/2021

2021/2022

7.4

12.3

9.89

350

256

1860

ND

752

117

ND

593

ND

85

6110

6823

ND

Babhekele Nene

Maize

–

Cowpea

intercrop

No

-till

2019/2020

2020/2021

70.5

65

2386

2468

ND

801

ND

1645

ND

198

ND

4294

2902

ND

Fikile Maphumolo

(Bergville

-

Mayizekane)

Maize

-

Cowpea

intercrop

No

-till

2019/2020

5

82.7

ND

976

ND

Fikile Maphumolo

M

-Maize

(control)

No

-till

2019/2020

128

38

ND

2266

ND

21

ND

Nomusa Shandu

(Bergville

-

Mayizekane)

Maize

–

Cowpea

intercrop

No

-till

2019/2020

2020/2021

779

45

1152

687

ND

134

ND

587

ND

1409

ND

1446

ND

Nomusa Shandu

M

-Maize

(control)

No

-till

2019/2020

2020/2021

24

2.9

2698

987

ND

6896

ND

2533

ND

63

117

ND

1338

Nomusa Shandu

Maize

-

Beans

intercrop

No

-till

2019/2020

2020/2021

25

12

146

569

ND

105

1309

ND

105

ND

29

ND

Simephi Hlatswhayo

(Bergville

- Eqeleni)

M

-Maize

(control)

No

-till

2019/2020

3

96

ND

798

208

ND

144

ND

Simephi

Hlatswhayo

M

-Maize

(control)

No

-till

2019/2020

1.4

3

ND

240

<LOQ

ND

Simephi

Hlatswhayo

M

-Maize

(control)

No

-till

2019/2020

1.9

17.6

ND

530

168

ND

<LOQ

ND

Simephi Hlatswhayo

M

-Maize

(control)

No

-till

2019/2020

ND

231

ND

613

144

ND

105

ND

Nthombakhe Zikode

(Bergville

- Eqeleni)

M

-Maize

(control)

No

-till

2020/2021

45.9

6987

ND

80

9546

438

ND

6703

ND

Nthombakhe Zikode

Maize

-

Beans

intercrop

No

-till

2020/2021

2.36

215

ND

137

ND

Nthombakhe Zikode

Maize

-

Cowpea

intercrop

No

-till

2020/2021

1.26

458

ND

1650

ND

Neliswe Msele

(Bergville

- Stulwane)

Maize

-

Beans

intercrop

No

-till

2019/2020

2020/2021

2021/2022

35

22

88

61

36

22

ND

695

ND

190

ND

29

ND

99

ND

66

Neliswe Msele

Maize

-

Cowpea

intercrop

No

-till

2019/2020

2020/2021

51.2

7.9

221

53

ND

400

907

<LOQ

271

ND

134

ND

1526

Neliswe Msele

M

-Maize

(control)

No

-till

2019/2020

2020/2021

2021/2022

81

25

31.5

90

254

9.70

ND

444

387

657

180

ND

291

ND

78

100

23

ND

2847

Neliswe Msele

Maize

-

Cowpea

intercrop

No

-till

2019/2020

2020/2021

48

25

17

18

ND

36

ND

Neliswe Msele

M

-Maize

(control)

No

-till

2019/2020

2020/2021

2021/2022

12

2.5

22

602

879

21

ND

615

1600

ND

1665

ND

223

ND

49

ND

647

393

Phumelele Hlongwane

(Bergville

-

Ezibomvini)

Maize

(control)

No

-till

2019/2020

2020/2021

2021/2022

7.9

5.89

1.35

21.4

22

9.25

ND

157

24

ND

420

ND

206

114

ND

217

ND

<LOQ

226

ND

15433

ND

Phumelele

Hlongwane

Maize

-

Beans

intercrop

No

-till

2019/2020

2020/2021

2021/2022

4.4

5.4

0.83

16.7

238

2.88

ND

302

ND

Phumelele

Hlongwane

Maize

-

Beans

intercrop

No

-till

2019/2020

2020/2021

2021/2022

ND

2.3

1.31

595

25

11.7

373

ND

127

24

ND

129

ND

Phumelele

Hlongwane

Maize

(control)

No

-till

2019/2020

2020/2021

17

125

85

698

ND

234

5750

1950

1623

177

159

ND

30

31

ND

842

Phumelele

Hlongwane

Maize

-

cover

crop

No

-till

2019/2020

34

100

ND

240

1418

518

ND

107

ND

Sibongile Mpulo

(Bergville

-

Vimbukhalo)

Maize

(control)

No

-till

2019/2020

2020/2021

1.3

ND

27

ND

12798

Sibongile Mpulo

Maize

(control)

No

-till

2019/2020

2020/2021

35

ND

23

41

ND

Sibongile Mpulo

Maize

No

-till

2019/2020

3.3

ND

Sibongile Mpulo

Maize

-

Cowpea

intercrop

No

-till

2019/2020

ND

Sibongile Mpulo

Maize

-

Beans

intercrop

No

-till

2019/2020

2020/2021

1.4

ND

2.4

ND

Sibongile Mpulo

Maize

-

Beans

intercrop

No

-till

2019/2020

2020/2021

10.2

2.8

78

89

ND

399

826

<LOQ

ND

1099

ND

Letta Ngubo (SKZN

-

Springvalley)

Maize

-

Beans

intercrop

No

-till

2019/2020

2020/2021

4.6

ND

Letta Ngubo

M

-Maize

(control)

No

-till

2019/2020

2020/2021

134

ND

81

ND

<LOQ

2467

ND

1646

ND

Zweni Ndaba

(Bergville

-

Emabunzini)

Maize

-

Beans

intercrop

No

-till

2019/2020

39

ND

Lethiwe Zimba

(Ndunwana)

Maize

No

-till

2019/2020

4.8

ND

56

ND

CD Xaba (SKZN

–

Madzikane)

Maize

from

plots

pooled

together

No

-till

2019/2020

2020/2021

2021/2022

9.2

ND

307

ND

30

ND

2050

ND

192

316

ND

53

ND

525

ND

CD Xaba

M

-Maize

(control)

No

-till

2019/2020

2020/2021

2021/2022

47.7

ND

2.03

ND

30

326

ND

1703

ND

205

ND

65

ND

221

4986

CD Xaba

Maize

-

Beans

intercrop

No

-till

2020/2021

2021/2022

12.9

4.18

697

44.2

ND

3942

ND

151

302

ND

100

ND

37

ND

95

Rita Ngobese

(Midlands

-

Gobizembe)

Maize

-

Beans

intercrop

No

-till

2020/2021

ND

211

724

ND

118

MartinaXulu

(Eswathini)

M

-Maize

(control)

No

-till

2020/2021

2021/2022

ND

4

54

134

ND

130

ND

367

ND

144

MartinaXulu

M

-Maize

(control)

No

-till

2020/2021

2021/2022

ND

111

798

ND

549

1146

ND

215

ND

113

55

ND

15736

61

MartinaXulu

Maize

-

Beans

intercrop

No

-till

2020/2021

2021/2022

ND

365

ND

644

ND

89

ND

-100.00

0.00

100.00

200.00

300.00

400.00

500.00

600.00

700.00

800.00

900.00

M-MaizeMaize/Drybean Maize/Cowpea

qPCRF.verticillioidesqPCRF.graminearum

-1000

-500

0

500

1000

1500

2000

2500

3000

3500

Aflatoxin

Fumonisin

Deoxynivalenol

15-Acetyl-DON

Ochratoxin A

Zearelanone

T2

HT-2

Diplodia toxin

Mycotoxinsin ppb(µg/kg)

M-MaizeMaize/Drybean Maize/Cowpea

Mean F.verticillioidesand F.graminearumlevels (pg/20µl)

measured from maize grain from three different cropping

systems over a three year period.

Mean mycotoxins (ppb) measured from maize grain from different

cropping systems over a three year period.

Discussion

•Mycotoxin concentrations varied from one season to another

•Monoculture maize systems showed higher levels offungi and mycotoxins

•Visualcorrelationobservedbetweenamountoffungiandspecificmycotoxinsassociatedwithit

•Soybean and/or stubble may be a host for the F. graminearumspp. complex (commercial

farmers)

-Sunflower is a suitable rotation crop

•Maize/cowpea intercrop systems had higher F. ve rt i ci ll io id esand F. graminearuminfections

compared to

monoculture maize systems

•Cowpea produce minimal crop residues, but maybe a host for the F. graminearumspp. complex

(smallholder farmers)

-Dry beans is a suitable rotation crop

•Diplodiatoxinmeasured for the firsttime in SA– monoculture maize– smallholder farmers