Biological control of Phytophthora megakarya the causative agent of cacao black pod disease in Camer

1
Biological control of Phytophthora megakarya
the causative agent of cacao black pod disease
in Cameroon
Status Prospects
Annual report 2002
Prepared by P.R.Tondje
Biocontrol and Applied Microbiology Unit
Institute of Agricultural Research for
Development
2
Background

• Cacao is one of the most important
  cash crops grown by farmers in Central and West
  Africa. The production of Central and West Africa
  represent more than 59.9 of the world production
  (Mossu, 1992 Padi and Owussu, 1998).
• In Cameroon, black pod disease can
  cause 80 losses in cacao farms when farms are
  left untreated by chemical fungicides. But heavy
  use of chemicals can cause disease resistance,
  non-target effects on beneficial microorganisms,
  humans and environment. And chemical fungicides
  prices are getting prohibitive for the cacao
  farmer.
• Since 1999 investigations on biological
  control of the causative agent of this disease
  are being conducted at IRAD. Bacterial and fungal
  endophytes, saprophytes, and epiphytes from
  natural agrosystems in the Center (NkometouIII)
  and Souh province (Ebolowa) of Cameroon are
  being isolated and screened for antagonism
  against Phytophthora megakarya, the causative
  agent of black pod disease(IRAD, 2001). Effective
  biocontrol microorganisms that are being selected
  through this lab and field testing are expected
  to contribute for reducing the use of chemical
  fungicides, and increasing farmers profit
  margins.
• Basically, three critical components
  are to be considered for an effective biocontrol
  system of plant diseases
  
• - Selection of effective biocontrol
  agents.(Fravel, 1999 Lo, 1997) and
  identification of traits, conditions and
  requirements for optimal performance of their
  specific mechanisms of action (Larkin et al,
  1998).
• - Good production and formulations
  techniques that give rise to high yielding of
  efficacious microbial propagules of high
  viability and stability (Fravel, 1999 Lo, 1997).
  .
• - Good delivery systems that can help
  to minimize growth of competitive microflora
  (Lo, 1997).
  
• In 2002 activities were particularly
  focused on field sampling for isolation and
  screening of microorganisms for their biocontrol
  potentials against Phytophthora megakarya.,
  Formulation experiments, small scale field
  testing in collaboration with farmers, and some
  preliminary investigation on mechanisms of action
  of some promising biocontrol candidates.

Phytophthora megakarya on a diseased cacao pod
Activities to achieve this objective were
implemented under the financial support of the
USAID-Chocolate industry sponsored STCP
(Sustainable tree Crops Program), and the
scientific collaboration of USDA, ARS and MM -
MARS (USA).
References Mossu, G. (1992) Cocoa . London MacMi
llan Education 103pp Padi, B. and G.K.
Owusu. (1998). Towards an integrated pest
management for sustainable cocoa production in
Ghana. . Proceedings of the 1st sustainable cocoa
workshop March, 29 to April, 3rd, 1998 Panama.
--
Muller, R.A
(1974) Effect of prophylactic measures on the
dissemination of Phytophthora palmivora. In P.H.
Gregory (ed) Phytophthora disease of cocoa
London, pp 169-78. Djiekpor, E.K, Goka. K.,
Lucas. P., Partiot. M.(1981) Brown rot of cocoa
pod due to Phytophthora species in Togo
Evaluation and control strategies. Café - Cacao -
The 25(4)263-268.
Dakwa, J. T. (1988b) A serious outbreak of the
black pod disease in a marginal area of Ghana.
Proc. 10th Int. Cocoa Res. Conf. 17-23 May 1987,
Santo Domingo Dominican Republic pp 407-4019
Fravel, D.R.(1999) Hurdles and bottlenecks on the
road to biocontrol of plant pathogens.
Australasian Plant Pathology 2853-56
IRAD (2001) Biocontrol of Phytophthora megakarya
the causative agent of cacao black pod disease in
Cameroon-Status prospects. Annual report of the
Biocontrol and Applied Microbiology Unit (BAMU).
9p. Lo.C.T (1997) Biological control of Turf dis
eases using Trichoderma harzianum. Plant
protection bulletin 39207-225.
Larkin.R.P., Roberts.D.P.and Gracia-Garza.J.A
(1998) Biological control of fungal diseases
P149-190 in Fungicidal activity. Edited by
D.H.Hutson and Miyamoto.J. John WileySons Ltd.

3
Some research highlights
SELECTION OF MICROBIALS MECHANISMS OF ACTION

• Trichoderma asperellum a new microbial for
  control of P.megakarya in cacao farms.

A complex of three very promising biocontrol
candidates for Phytophthora megakarya the
causative agent of cacao black pod disease,
(PR10,PR11,PR12) was isolated from a rotten tuber
of Xanthosoma sagitifolium in a farmers mixed
crops field around Yaounde (Etoug Ebe). The same
level of biocontrol effectiveness was observed
for a microbial that was isolated from the forest
reserve of Dja by Dr.Gary Samuels USDA-ARS. These
isolates from different origin (Etoug Ebe and the
Dja forest reserve) were identified as isolates
of Trichoderma asperellum. In the lab, these
isolates of Trichoderma asperellum has proven to
be a very powerful mycoparasites of P.megakarya.
More over, very significant reduction of disease
incidence was observed in field experiments
during the 2002 cacao campaign. In addition,
According to Dr. Prakash Hebbar Masterfoods inc
USA this Cameroon strains of T.asperellum
expressed mycoparasitism for Crinipellis
perniciosa in lab conditions.
Effective control was observed with Trichoderma
asperellum (659-7) in the farm.

• Some endophytic Geniculosporium spp. from cacao
  leaves, can reduce P.megakarya incidence using
  different mechanisms of action.

A novel method for screening for biocontrol
activity for Phytophthora megakarya was developed
using endophytic strains of Geniculosporium sp
(BC13, BC181, BC118, BC108, BC177) from cacao
leaves, on cacao pod husk pieces. Results reveal
more specific responses of biocontrol candidates
on various stages of the disease cycle on cacao
pods, notably pod infection, mycelia growth
inside infected tissues, and fungal sporulation.
Results, suggest the necessity to target these
key steps during the screening process for
biocontrol candidates. .
The incorporation of biocontrol formulations
composed of multiple microbial strains and
multiple mechanisms of action will be
investigated during the coming cacao campaign.
4
FORMULATION, FIELD TESTING, EXTENTION

• A new formulation of biocontrol agents is being
  developed

• A new formulation based on local low cost product
  has been developed by the IRAD and is being
  improved. This formulation can provide nutriments
  for Trichoderma propagules to survive on cacao
  pod surface,

A treated cacao pod with the new formulation of
T.asperellum

• Encouraging results are being observed in field
  experiments

Fig1 Effect of field treatment with isolates of
Trichoderma asperellum(PR12,657-9),PR10) on
black pod disease occurrence in a farmers field
at -ESSE.

• Field tests were conducted in collaboration with
  farmers in selected farmers fields at ESSE
  (NyongSo Division and NkometouIII (Lekié
  Division)
• Very encouraging results are being observed and
  black pod disease occurrence was reduced on
  treatments where Trichoderma asperellum was
  applied.

? National and international cooperation for the
promotion of microbial biocontrol research.

• Collaboration with University of Dschang ( Pr.
  Foko Jacob).
  
• Two students from the University of Dschang
  (Cameroon) successfully completed their level
  four training after1 month of research in the
  Biocontrol and Applied Microbiology Unit of IRAD
  
• Mbarga Joseph and Atangana J.B - Research
  theme Isolation and storage of of endophytes
  from cacao leaves and pods..
  
• ? Collaboration with cacao farmers
  organizations( FORCE, FUPROCAM, FEGAISEM) Field
  collection of samples from cacao plants and
  soils, for the isolation of microorganisms,
  and the setting up of field trials for
  biocontrol agents were conducted in
  collaboration with farmers. Working with pilot
  farmers help them be aware of the presence of
  beneficial microorganisms in their farms and
  surely will be helpful for the adoption of
  the microbial biocontrol strategy.

5
NEXT STEPS

• Large scale field testing of promising
  microbial strains.
  
• Isolation and screening of microorganisms will be
  pursued in the Center and the South provinces,
  and extended to the South West province of
  Cameroon, and in forest reserves (Korup, Dja)..
• Determination of mechanisms of action of the
  promising microbial biocontrol candidates.
  
• Fermentation trials for low cost mass production
  of effective biocontrol candidates.
  
• Formulation trials for promising biocontrol
  agents using local byproducts will be pursued..
  
• In addition, the Biocontrol and Applied
  Microbiology Unit of IRAD (BAMU) is ready to
  collaborate
  
• ? With the International Atomic Energy Agency
  (IAEA) to study environmental behavior of
  inundative sprayed microbial biocontrol agents in
  cacao ecosystems, using radiotracer methods.
• ? for the extension of microbial biocontrol
  investigation to the biocontrol of insect pests
  and the biocontrol of more fungal and
  bacterial pathogens of plant crops species in
  Cameroon.
  
  ? for the extension
  of the use of beneficial microorganisms to the
  bioconversion and upgrading of some agricultural
  wastes and products (cocoa pod husks, ) for the
  improvement of their digestibility and their
  enrichment in proteins for animal feed.

Constraints

• An appropriate working space is urgently needed
  for the biocontrol and applied microbiology unit
  of IRAD. This will avoid possible very damaging
  contamination of the living collection of fungi
  in the plant pathology lab that is now hosting
  the biocontrol of plant diseases unit, and will
  facilitate the extension of activities and the
  purchase of more adapted lab materials.

6
Impact of results obtained in 2002
These results are very encouraging for scientists
in Cameroon and in all Africa cacao producing
countries a lot of interest is being observed
within farmers in pilot experiment sites. This is
a contribution for proof that even more
interesting biocontrol microbes can be found in
natural ecosystems of Cameroon.
We wish to extend field testing of our better
strains in other cacao producing countries where
P.megakarya is the main constraint., and can
collaborate with scientists from cacao producing
countries of Africa for a setting up of effective
biocontrol for black pod disease in Africa.
Associated scientists and Institutions
Activity Coordinator Pierre Roger Tondje
(IRAD/Cameroon) Research Team Cameroon
Pierre Roger Tondje (Msc)Plant Pathologist IRAD
Begoude Boyogueno Didier- Agronomist IRAD
Etienne Nyemb Tshomb (Bsc)-Plant Pathologist
IRAD Associated Scientists Cameroon Pr. J
acob Foko (PhD) Plant pathologist (University of
Dschang) Stephan Weise (PhD) Weed Scientist(IITA)
Jim Gockowski (PhD) Agro - economist (IITA) J
ose-Luis Rueda(PhD) Plant pathologist geneticist
(STCP) USA Prakash K. Hebbar (PhD) Microbiologis
t MM MARS USA, John Bowers (PhD) Plant
Pathologist USDA, ARS-USA Gary Samuels (PhD)
Research Mycologist USDA, ARS-USA, Robert D.
Lumsden (PhD) ACRI/USDA- USA. UK Julie Flood (Ph
D) Plant Pathologist CABI Biosciences UK, Keith
Holmes (PhD) Plant pathologist CABI Biosciences
UK, Harry Evans (PhD) Plant pathologist CABI
Biosciences UK , M.W. Shaw (PhD) University of
Reading UK

• Associated institutions
• - USAID
• - STCP
• - IITA
• USDA, .ARS
• MM- Mars USA
• - CABI biosciences, UK
• - ACRI, USA
• - CRIN (Nigeria)
• - CRIG (Ghana)
• - CNRA (Cote dIvoire)
• - University of Dschang- (Cameroon)
• - University of Yaounde I (Cameroon)
• - University of Reading (UK)

7
General conclusion
The use of multiple beneficial microorganisms
from our natural ecosystems and multiple
mechanisms of action, combined with improved
formulation and delivery systems, will be
emphasized in our future investigations and could
help, in combination with other disease control
strategies, for developing effective Integrated
Disease Management for cacao black pod disease.
Acronyms

• - USAID (United State Agency for
  International Development)
  
• - STCP ( Sustainable Tree Crops Program)
• - IITA ( International Institute of Tropical
  Agriculture)
  
• USDA, .ARS (United States Department of
  Agriculture, Agricultural Research Services)
  
• MM- Mars USA
• IAEA (International Atomic Energy Agency)
• - CABI biosciences, UK (Commonwealth
  Agricultural Bureau International)
  
• - ACRI, USA (American Cocoa Research
  Institute)
  
• - CRIN (Nigeria) (Cocoa Research Institute
  of Nigeria)
  
• - CRIG (Ghana) (Cocoa Research Institute of
  Ghana)
  
• - CNRA (Cote dIvoire) (Centre National de
  Recherche Agronomique)
  
• - IRAD (Institut de Recherche Agricole pour le
  Developpement)
  
• - PNVRA ( Programme National de Vulgarisation
  et de Recherche Agricole)
  
• - FUPROCAM (Federation des Unions des
  Producteurs de Cacao du Mbam et Inoubou)
  
• - FEGAISEM ( Federation des Groupements
  Agricoles de Matomb)
  
• - FORCE (Confederation des Organisations
  Rurales pour le Cameroun Economique)