ROOT-KNOT NEMATODE MANAGEMENT IN ZIMBABWE :

CURRENT AND FUTURE TRENDS

48th TOBACCO WORKERS CONFERENCE, SOUTH CAROLINA

P.T. Makunde, T.S. Mahere, C. Chinheya and S. Dimbi

Tobacco Research Board, Zimbabwe

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NEMATODE CONTROL IN ZIMBABWEHas mostly relied on the use of the fumigants eg•Methyl-bromide in

the seedbeds and

• 1.3 D and EDB in the field.

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ADVANTAGES OF FUMIGANT NEMATICIDES

• Good return on investment

• have a broad-spectrum of activity,

• very effective when correctly applied

• Long period of control

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INTRODUCTION

• In line with international trends the fumigants – no longer acceptable for use on tobacco.

• What options are available for nematode control?

SOME AGROCHEMICALS NO LONGER RECOMMENDED FOR USE ON TOBACCO IN ZIMBABWE

ACTIVE INGREDIENT CATEGORY1,3-Dichrolopropene/Methyl bromide NematicideAcephate, Thiodicarb InsecticidesAlachlor, Trifluralin HerbicideAldicarb Nematicide/InsecticideBenomyl FungicideDimethenamid, Metolachlor, HerbicidesEthylene dibromide NematicideFenvalerate InsecticideMethamidophos, Monocrotophos Insecticides

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ALTERNATIVE SYNTHETIC NEMATICIDES

TRB working on

• Chemical alternatives (seedbed and field)

• Genetic resistance

• Cultural control K RK71

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SOME WORK ON THE CHEMICAL ALTERNATIVES

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MATERIALS AND METHODS

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Evaluation of Agrochemicals – Seedbed

• 1m2 beds • 3 blocks

• 2 varieties used

• 0.5 m x 0.45 m area pulled out for assessment

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Evaluation of Agrochemicals - Field

• A susceptible variety & a resistant var• Trials conducted over three seasons

• 3 rows/plot• 32 plants/row• 5 treatments• 3 blocks

32

THE TREATMENTS1. an untreated control,

2. a standard,

3. The test product at the lab determined rate,

4. a lower

5. a higher rate

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NEMATODE POPULATION EVALUATION• Soil samples collected

from around the base of the plants

• Taken to the greenhouse

• Susceptible tomato plants planted

• Galling on the tomato plants indicates nematode populations

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GALLING ON TOMATO PLANTS

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ROOT GALLING ASSESSMENTS

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SCORE DEGREE OF GALLING0 Free from galls 1 < 5 galls2 Trace to 25 galls3 20 – 100 galls4 Numerous galls, mostly discrete5 Numerous galls, many coalesced6 Heavy, mostly coalesced7 Very heavy, mass invasion, slight root growth8 Mass invasion, no root development

Daulton and Nasbaum (1961) scale of 0 – 8ROOT GALLING ASSESSMENTS

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Alternative NematicidesThe following were evaluated;

• Metham sodium• Metham potassium• Methyl iodide• Fluopyram• Fluensulfone (MCW-2)

methyl isothiocyanategenerators

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1. METHAM SODIUM

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• Beds watered - activate weeds & nematodes.

• MeNa applied as a drench

• Covered - polythene sheets for 7 days.

2.

METHAM SODIUM - SEEDBEDS

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METHAM SODIUM - APPLICATION

•Soil aerated - a fine tilth with a spade.

•Sowing - 28 days after product application.

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THE RESULTS

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0

200

400

600

800

1000

Grass Weeds Broadleaf weeds

No o

f wee

ds p

er m

2

Weed Type

ControlMeBrMeNa - 50 mlMeNa- 100 mlMeNa - 150 ml

Weed populations in MeNa treated plots

a

a

b b b b b b b b

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ROOT GALLING ON TOBACCO SEEDLINGS

012345678

Control Methylbromide

MeNa50ml

MeNa100ml

MeNa150ml

Gall

ratin

g (S

cale

0 -

8)a

b

aa a

•Root galling low

•All three rates effective

MeBr MeNa Cont

The observation: Seedlings in MeBr, MeNa and untreated plots

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METHAM SODIUM FIELD EVALUATION

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Metham Sodium – Field Application • A liquid formulation

• Applied using fumigation guns or tractor tines

• Fumigation conducted 14 days before planting

MANUAL APPLICATIONTractor Application

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0

1

2

3

4

5

6

Gal

l rat

ing

(sca

le 0

-8)

Treatment

a

b

c

b b b

RKN susceptible Variety RKN resistant Variety

Performance of Metham sodium in the field

ab

a aaa

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SUMMARY – METHAM SODIUM USE•Broad spectrum activity in seedbeds -controls nematodes and weeds

•Registered at the rate of 100 ml in 4 L water/m2

•In the field - applied at the rate of 4 ml/planting station

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CHALLENGES WITH METHAM SODIUM USE IN THE FIELD

• Can give inconsistent performance if not properly applied.

• Reported to be corrosive to equipment

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2. METHAM POTASSIUM &3. METHAM IODIDE

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APPLICATION METHOD

• MeK – same as Metham sodium

• Methyl Iodide -applied under 125 gauge polythene sheets.

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2. RESULTS – METHAM POTASSIUM

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0

50

100

150

200

250

300

Broadleaf grasses

No.

of w

eeds

per

m2

area

Weed type

Untreated controlMe-BrMe-Na (std)Me-K 80 ml/m2Me-K 100 ml/m2Me-K 120 ml/m2

Weed populations in Me-K treated plots

a

b b b b b

a

b b b b b

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00.5

11.5

22.5

33.5

4

Cont Me-Br Me-K80

ml/m2

Me-K100

ml/m2

Me-K120

ml/m2

Cont Me-Br Me-K80

ml/m2

Me-K100

ml/m2

Me-K120

ml/m2

K M10 K RK66

ROOT-KNOT NEMATODE ON SEEDLINGS

a

b

c dd a b b b b

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3. RESULTS - METHYL IODIDE

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WEED COUNTS - METHYL IODIDE

0

50

100

150

200

250

300

350

Broadleaf Grassses

No.

of w

eeds

per

m2

area

Weed type

Untreated control

Methyl Bromide

Methyl iodide 10 g/m2

Methyl iodide 20 g/m2

Methyl iodide 30 g/m2a

c cb c

c cb

c

a

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RKN GALL RATINGS ON SEEDLINGS FROM METHYL IODIDE TREATED PLOTS AT PULLING

0

1

2

3

Untreatedcontrol

Methylbromide

Methyliodide 10

g/m2

Methyliodide 20

g/m2

Methyliodide 30

g/m2

a

b b b b

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4. FLUOPYRAM

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0

0.5

1

1.5

2

Root

gal

ling

(sca

le 0

-8)

Treatment

Fluopyram Applied at sowing

0

0.5

1

1.5

2

Root

gal

ling

(sca

le 0

-8)

Treatment

Fluopyram Applied 7 days after sowing

RKN GALL RATINGS AFTER FLUOPYRAM APPLICATION

a aaa

b

a aaab

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00.5

11.5

22.5

33.5

4

Root

gal

ling

(sca

le 0

-8)

Treatment

Fluopyram Applied at sowing

00.5

11.5

22.5

33.5

4

Root

gal

ling

(sca

le 0

-8)

Treatment

Fluopyram Applied 7 days after sowing

RKN GALL RATINGS AFTER FLUOPYRAM APPLICATION

a aaa

b

a

bb

a

b

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FLUOPYRAM – FIELD TRIALS

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0

1

2

3

4

5

6

7

3 WAP 8 WAP 13 WAP

Gal

l rat

ing

(0 –

8)

Untreated control Metham-sodium stdFenamiphos std Velum 500SCVelum 400SC (0.05 ml/ p.s.) Velum Split application

Galling of tomato plants from soil assayed in the greenhouse

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Root galling in Fluopyram treated plots - 1

00.5

11.5

22.5

33.5

44.5

5

Root

-kno

t gal

ling

(Sca

le 0

-8)

KM10 (S) K RK72 (R)

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012345678

Con

trol

Fena

(STD

)

Fluo

(0.3

L/h

a)

Fluo

(0.6

L/h

a)

Fluo

(0.9

L/h

a)

Fluo

(1.2

L/h

a)

Con

trol

Fena

(STD

)

Fluo

(0.3

L/h

a)

Fluo

(0.6

L/h

a)

Fluo

(0.9

L/h

a)

Fluo

(1.2

L/h

a)

K M10 K RK64

Root

-kno

t gal

ling

(0 -

8)

Root galling in Fluopyram treated plots - 2

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• Effective for rkn control both in the seedbed and field

• Only registered for field use @ 0.9 L/ha (resistance management)

• No herbicidal effect - combine with a pre-emergent herbicide (eg clomazone)

Fluopyram - Summary

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5. FLUENSULFONE (MCW-2) -ADAMA

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1. Untreated control2. Metham sodium (STD) 60 L/ha3. Oxamyl (STD) 3 L/ha4. MCW-2 2 L/ha5. MCW-2 4 L/ha6. MCW-2 6 L/ha7. MCW-2 8 L/ha

FLUENSULFONE – FIELD TRIALS

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0

2

4

6

8Un

treat

ed c

ontro

l

Met

ham

-sod

ium

std

Oxa

myl

std

MC

W-2

(2 L

/Ha)

MC

W-2

(4 L

/Ha)

MC

W-2

(6 L

/Ha)

MC

W-2

(8 L

/Ha)

Untre

ated

con

trol

Met

ham

-sod

ium

std

Oxa

myl

std

MC

W-2

(2 L

/Ha)

MC

W-2

(4 L

/Ha)

MC

W-2

(6 L

/Ha)

MC

W-2

(8 L

/Ha)

K M10 T75

Gal

l rat

ing

(0 –

8)

Root-knot nematode gall rating - 2015

ab

a a a a aaaa aaab

c

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012345678

Untre

ated

con

trol

Oxa

myl

std

MC

W-2

(2 L

/Ha)

MC

W-2

(4 L

/Ha)

MC

W-2

(6 L

/Ha)

MC

W-2

(8 L

/Ha)

Untre

ated

con

trol

Oxa

myl

std

MC

W-2

(2 L

/Ha)

MC

W-2

(4 L

/Ha)

MC

W-2

(6 L

/Ha)

MC

W-2

(8 L

/Ha)

K M10 T75

Gal

l rat

ing

(0 –

8)

Root-knot nematode gall rating - 2016

a a a aaab bbb

d

c

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• Registered for use

• Applied in planting water @ 2 L in 450 L /ha)

FLUENSULFONE (MCW-2) : SUMMARY

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ALTERNATIVE NEMATICIDES ON TOBACCO IN ZIM CHEMICAL NAME COMMON NAME FOR USE

1. Potassium N-methyldithiocarbamate

Metham Potassium Seedbeds

2. Iodomethane Methyl iodide Seedbeds3. Tetrahydro-3,5-dimethyl-2H-

1,3,5- thiadiazine-2-thioneDazomet®/Basamid® Seedbeds

4. Sodium N-methyldithiocarbamate

Metham Sodium Seedbeds/ Field

5. Fluopyram - Bayer Velum® Field

6. Fluensulfone - Adama MCW 2 Field

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NON-CHEMICAL ALTERNATIVES

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NON-CHEMICAL ALTERNATIVES - SEEDBEDS

• The floating tray system

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• Developed a pine bark soilless media and a float fertilizer.

• Polystyrene tray factory put up at Kutsaga.

• Growers trained on the use of the floating tray technique

200, 242 & 120 cells2:1:2Pine bark based

FLOATING TRAY SYSTEM

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TRB agronomistTRB extentionist

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THE FLOATING TRAY SYSTEM - ADOPTION

• Adoption rate reported to be 30-40%

• Float trays sales data show the increased use

106634

84,092

226,925

351,743359,615

0

100000

200000

300000

400000

2013 2014 2015 2016 2017

No.

of f

loat

tray

s so

ld fr

om TR

B

Year

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CHALLENGE : IMPENDING BAN OF STYROFOAM PRODUCTS

• Styrofoam already banned for food packaging

• TRB searching for recyclable alternatives & factory upgrade

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CULTURAL PRACTISES –CROP ROTATIONS

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CROP ROTATIONS• Traditionally : tobacco - 3/4 years grass-

tobacco

• Land sizes smaller post land reform

• Need for shorter term rotation crops

• Currently bulking up seed for a Katamboragrass – effective in18 months

KATAMBORA GRASS

GHR1 VARIETY

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RESISTANT VARIETIES

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• All recently developed Kutsaga varieties (K RK) have varying levels of root knot nematode resistance

RESISTANT VARIETIESVARIETY RESISTANCE LEVELSVARIETY CLASSIFICATION K RK64, K RK71, K RK72, T70, T 74, T75 Very high resistance

K RK29, T73 ,T76 High resistance

K RK66, K RK26R Moderate resistance

K M10 SusceptibleKM10 T 75

ROOT GALLING IN A SUSCEPTIBLE AND RESISTANT VARIETY POST-REAPING

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SUSCEPTIBLE VS RESISTANT VARS UNDER HIGH NEMATODE PRESSURE

KM10 (S)K RK66 (R)

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UNFUMIGATED KM10 FUMIGATED KM10

KM10 IN LAND WITH HIGH NEMATODE PRESSURE

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K RK71 IN LAND WITH HIGH NEMATODE PRESSURE

UNFUMIGATED FUMIGATEDUNFUMIGATED FUMIGATED

K RK72 IN LAND WITH HIGH NEMATODE PRESSURE

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CONCLUSIONOn their own, alternatives not as effective as the fumigants.....IPM approach – has good results• Resistant varieties

• The synthetic nematicides

• Good Agricultural practices (rotations, other tobacco best practices)

THE TEAM BEHIND THE WORK

Tafadzwa Mahere Dr Cleopas ChinheyaPrivilege Makunde

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C36

_Dim

bi.p

dfT

WC

2018

(48)

- D

ocum

ent n

ot p

eer-

revi

ewed

Thank you

2018

_TW

C36

_Dim

bi.p

dfT

WC

2018

(48)

- D

ocum

ent n

ot p

eer-

revi

ewed