Could the Desmodium ‘push-pull’ system for Striga control ... · The push-pull strategy in the...
Transcript of Could the Desmodium ‘push-pull’ system for Striga control ... · The push-pull strategy in the...
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Could the Desmodium ‘push-pull’system for Striga control in Africa work on Phelipanche ramosa and Orobanche crenata?
Mohamed Shrif • Alistair Murdoch • Irene Mueller-Harvey
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DESMODIUM
PUSH
MAIZENapier Desmodium Maize
Pho
to b
y S
am
Njih
ia, K
AR
I, Ke
nya
Push-pull habitat management system designed for control of maize stem borer
Plot sizes: 15 x 15 to 50 x 50 metres
System developed by Khan and co-workers at ICIPE in Kenya
NAPIER
PULL
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The push-pull strategy in the field
Photo from Francis Muyecko, KARI, Kenya
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SERENDIPITY!
“But my main problem is NOT
stem borer, it’s Striga” “And mine is
actually Orobanche/
Phelipanche”
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Objectives
• To determine whether this ‘push-pull’ control
system developed by ICIPE in Western Kenya using
Desmodium intortum (Silverleaf) and D. uncinatum
(Greenleaf), could be adapted to control
Phelipanche and Orobanche
• Results here for two Greek seed lots (D1 and D6) of
Phelipanche ramosa kindly supplied by Falia
• Results not presented today on Orobanche crenata
and also for Striga hermonthica.
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Experimental system
Reading University, 2009/10
Lower pots
Host plants of Striga (Millet), Pea for O.crenataand Tomato for Phelipanche ramosa
Upper pots
Desmodium Greenleaf or Desmodium Silverleaf
Tom
atoTube Tube
Desmodium
Phelipanche ramosa
No
Desmodium
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Shoots per pot LSD (P=0.05) = 32.80
P.
ram
osa
D1
Sil
verl
eaf
+ D
1
Gre
en
leaf
+ D
1
P.
ram
osa
D6
Sil
verl
eaf
+ D
6
Gre
en
leaf
+ D
6
Shoots of P.ramosa
parasitising tomato
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Shoot dry weight per pot , mg LSD (P=0.05) = 4.1 mg
P.
ram
osa
D1
Sil
verl
eaf
+ D
1
Gre
en
leaf
+ D
1
P.
ram
osa
D6
Sil
verl
eaf
+ D
6
Gre
en
leaf
+ D
6
Dry weight of shoots of P.ramosa
(D1 & D6) parasitising tomato
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Flavonoid compounds affecting
Striga hermonthica
From Pickett, Hamilton, Hooper, Khan and Midega (2010) Ann. Rev. Phytopathol. 2010.48:161-
177
B A
HPLC trace• Dual action
A. Germination stimulation
B. Inhibition of subsequent growth
• Overall effects
– reduced attachment to host
– suicidal germination
Germination stimulationInhibition ofsubsequent growth
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Attachments (in vitro) study using conditioned and GR24-stimulated P. ramosa seeds and Desmodium
greenleaf exudates at a range of concentrations
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So far so good
Now for
the bad news!
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LSD, P=0.05
Height, cm, of tomato 14 weeks after planting
Co
ntr
ol
Sil
verl
eaf
Gre
en
leaf
P.
ram
osa
D1
Sil
verl
eaf
+ D
1
Gre
en
leaf
+ D
1
P.
ram
osa
D6
Sil
verl
eaf
+ D
6
Gre
en
leaf
+ D
6
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Negative effects of Desmodium
and P. ramosa on tomato
Treatment Height Shoot weight Fruit weight
Tomato only 120 cm 55 mg 31 mg
Desmodium
uncinatum (Silverleaf)- 19% - 39% - 68%
Desmodium intortum
(Greenleaf)- 21% - 38% - 62%
P. ramosa seed lot D1 - 25% - 43% - 39%
P. ramosa seed lot D1
+ Silverleaf- 48% - 69% - 36%
P. ramosa seed lot D1
+ Greenleaf- 36% - 69% - 81 %
LSD (%) P = 0.05 8 % 13% 6%
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• Both Desmodium species effectively reduced the
number and dry weight of Ph. ramosa shoots parasitising
tomato
• Ph. ramosa seed lot D1 was affected by the Desmodium
more than D6
• Desmodium, however, reduced tomato height and yield
So sorry, the answer to the question posed is yes
and no
Conclusions
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Our grateful thanks to the government of Libya for a scholarship to Mohamed Shrif
To Laurence Hansen and Caroline Hadley for technical assistance (Plant Environment Laboratory),
To Ron Brown (Chemistry& Biochemistry Laboratory) for their technical assistance
Acknowledgements