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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
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
The push-pull strategy in the field
Photo from Francis Muyecko, KARI, Kenya
SERENDIPITY!
“But my main problem is NOT
stem borer, it’s Striga” “And mine is
actually Orobanche/
Phelipanche”
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.
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
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
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
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
Attachments (in vitro) study using conditioned and GR24-stimulated P. ramosa seeds and Desmodium
greenleaf exudates at a range of concentrations
So far so good
Now for
the bad news!
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
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%
• 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
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