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ROOT-KNOT NEMATODE CONTROL
ON TOBACCO: ALTERNATIVES TO FUMIGANT NEMATICIDES
CORESTA CONGRESS 2014 – AP 08
TOBACCO RESEARCH BOARD KUTSAGA
P.T. Makunde, T.S. Mahere and S. Dimbi
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Background
Objectives
Materials and Methods
Results and Discussion
Conclusion
Acknowledgments
Presentation Outline
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Tobacco is the largest
agricultural export
commodity in Zimbabwe
Flue-cured tobacco –
largest proportion
Mostly grown on sandy soils - Root-knot nematodes (RKN) is a very serious pest
Background
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Background cont’d
Resistant
Cultivars
Crop
rotations
Methyl bromide,
EDB, 1,3-D...
- Extremely effective & inexpensive
Sunnhemp,
Katambora Rhodes grass
Chemical
(Fumigants)
RKN - Management
... they pose a serious threat to the ecological balance
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Thus globally, there has been a general trend of banning, phasing out and de-registration of most fumigant nematicides
Hence, there is a need for research aimed at developing economically feasible and environmentally compatible alternatives
Background cont’d
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To evaluate/validate the efficacy of
alternative chemical nematicides for
RKN control in:
- conventional tobacco seedling
production system and
- tobacco fields.
Objectives
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Conventional seedbed trials
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Materials and Methods
Conventional seedbed trials
Design: Split-plot in 3 RCB
Main plot: Tobacco cultivars
K M10 & K RK64
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Materials and Methods cont’d
Conventional seedbed trials
1. Untreated control
2. Methyl bromide (35 g/m2 )
3. Metham sodium (100 ml/m2 )
4. Metham potassium (100 ml/m2 )
5. 3 rates: Oxamyl
Sub plot : Nematicides
1. Untreated control
2. Methyl bromide (35 g/m2 )
3. Fluopyram (0.5 ml/m2)
4. Fluopyram (1 ml/m2)
5. Fluopyram (2 ml/m2)
1st trial 2nd trial
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Root-knot nematode assessment
Daulton and Nasbaum (1961) scale of 0 – 8
Infection class Index value Degree of galling
0 0 Free from galls
1 1 < 5 galls
2 5 Trace to 25 galls
3 10 20 – 100 galls
4 25 Moderate galls
5 50 Many coalesced
6 75 Heavy, mostly coalesced
7 90 Very heavy, mass invasions
8 100 Mass invasion, no root development
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Data Analysis
The RKN gall ratings were subjected to analysis
of variance (ANOVA) using GenStat 17th
edition (2014, VSN International)
Treatment means were separated using the
Least Significance Difference at P<0.05
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00.5
11.5
22.5
33.5
44.5
Ro
ot-
kn
ot
ga
llin
g (
Sc
ale
0 -
8)
K RK64
a a
Fig. 1
Results – Conventional seedbeds
K M10
a a a
b b
c
a a b
a a a
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MeBr MeNa Cont
Key observation: Seedlings in MeBr, MeNa and
untreated plots
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0
0.5
1
1.5
2
2.5
Ro
ot-
kn
ot
ga
llin
g (
Sc
ale
0 -
8)
Results – Conventional seedbeds
cont’d At sowing Seven days after
sowing Fig. 2
a a a a
b
a a
b b b
K M10
only
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Conventional seedbed
Fluopyram, Me-K, Me-Na and Oxamyl
(20 L/Ha) gave exceptionally good
control of RKN.
Seedlings in Me-K treated plots
consistently had clean roots.
Results – Summary
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Field trials
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Materials and Methods
K M10, a nematode
susceptible tobacco variety
was grown for two seasons.
Design: Split-plot in 3 RCB.
Main plot: Tobacco cultivars
(K M10 & K RK64).
Field trials
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Materials and Methods cont’d
Field trials
1. Untreated control
2. Fenamiphos
3. Sesamin (10 L/Ha)
4. Sesamin (15 L/Ha)
5. Sesamin (20 L/Ha)
Sub plot : Nematicides 1. Untreated control
2. Fenamiphos
3. Fluopyram (0.3 L/Ha)
4. Fluopyram (0.6 L/Ha)
5. Fluopyram (0.9 L/Ha)
6. Fluopyram (1.2 L/Ha)
7. 3 rates: Abamectin
(2.5, 3 and 3.5 L/Ha)
1st trial 2nd trial
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Materials and Methods cont’d
Field trials
Sub plot : Nematicides
1. Untreated control
2. Fenamiphos std
3. Oxamyl 10 G (15 kg/Ha)
4. Oxamyl 10 G (22.5 kg/Ha)
5. Oxamyl 10 G (37.5 kg/Ha)
6. Fenamiphos (New source)
7. Fluopyram 400 EC (0.9 L/Ha)
8. Fluopyram 500 EC (0.9 L/Ha)
3rd trial
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Tobacco seedlings used were raised in
float beds in a pine bark based soilless
media (Kutsaga Gromix)
Spacing: 120 cm x 56 cm (14 881 plants
/ha)
Standard Cultural practices were done
Materials and Methods cont’d
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RKN assessment - Daulton and Nasbaum (1961) scale of 0 – 8
Data Analysis
The RKN gall ratings were subjected to analysis of variance (ANOVA) using GenStat 17th edition (2014, VSN International)
Treatment means were separated using the Least Significance Difference at P<0.05
Materials and Methods cont’d
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012345678
Ro
ot-
kn
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ga
llin
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0 -
8) K M10
Results – Tobacco fields
K RK64 Fig. 3
a a a a a
a a b b b
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01234567
Ro
ot-
kn
ot
ga
llin
g (
0 -
8)
Results – Tobacco fields cont’d
K RK64 K M10
Fig. 4
a a a a
b b
c c c
a a a a a a a a a
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0
1
2
3
4
5
6
7
Ro
ot-
kn
ot
ga
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0 -
8)
Results – Tobacco fields cont’d
K RK64
K M10
Fig. 5
a a a a a a a a
a a a a a
b b b
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Key Observation
Results – Tobacco fields cont’d
Untreated control
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Key Observation
Results – Tobacco fields cont’d
Fenamiphos
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Key Observation
Results – Tobacco fields cont’d
Fluo.(Vellum)
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Key Observation
Results – Tobacco fields cont’d
Aba.(Solvigo)
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Field trials
Sesamin - the middle (15 L/ha) and high rate (20 L/ha) gave some control of nematodes.
All tested rates of Fluopyram were effective for RKN control.
Oxamyl significantly control RKN better than Fenamiphos.
Results – Summary
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Me-Na, Me-K, Fluopyram and Oxamyl can be effectively used in tobacco seedling production.
Velum, Oxamyl and Sesamin, have a place in nematode control (Fields).
However, for season-long nematode control – multiple applications seem to be necessary.
Conclusion
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Acknowledgements
Tobacco Research Board Management
and Staff
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