In this issue: Plant health is an important concern for all. IITA believes that ensuring plant health is pivotal to improve agricultural productivity and food security, and reduce poverty. It is also a key element in IITA’s strategy of intensifying sustainable agriculture. Containing biological threats, among other things, to food security is the real national defense, says IITA DG Hartmann.

1. R4D Review
Issue 6, March 2011
Climate change and plant health
Healthy banana
tissue culture industry
Safe exchange of germplasm
Germ-free germplasm
In Kanti Rawal’s footsteps
Restoring the IITA Forest
Investing in aflasafeTM
Clean seed systems:
Banana, cassava, and yam
A hot bath for the suckers!
Novel surveillance system
Transgenic banana for Africa
Researcher inspecting soybean seeds for
pathogen cultures. Photo by J. Oliver, IITA.
www.iita.org

2. contents
2 EDITOR’S NOTE
Plant health matters
4Nigeria gets improved
Plant health is an important concern cassava
for all. IITA believes that ensuring plant Better soybean
health is pivotal to increase productivity
and in its strategy of sustainable Conference on
agriculture intensification. Containing humid tropics
biological threats, among other things, UPoCA gives
to food security is the real national farmers a lifeline
defense.
Liberia and Ghana to
6 REVIEW
Climate change and plant health 6
develop agriculture
Agriculture has been pinpointed as one of the factors contributing
to climate change. This article discusses what research the
CGIAR centers, including IITA, are doing to cushion the negative
impacts of climate change.
12 FEATURES
Towards a healthy banana industry in East Africa 12
Banana production in East Africa has been riddled with problems,
including pests and diseases. IITA scientist Thomas Dubois did a
SWOT analysis to determine what ingredients are needed for the
banana tissue culture industry to succeed.
GHU: Gateway for the safe exchange of germplasm 19
IITA’s Germplasm Health Unit is delivering a critical function.
Virologist and GHU Head Lava Kumar walks us through the
important work being undertaken to ensure the safe exchange of
international public goods.
Conservation of germ-free germplasm 26
Conserving clean genetic resources for agricultural sustainability
and the preservation of diversity is imperative if we want to ensure
global food security.
In Kanti Rawal’s footsteps 28
Kanti Rawal, IITA’s plant geneticist in the 1970s, traveled 38,000
km around Nigeria and Niger to collect wild and domesticated
accessions of cowpea. The authors—Remy Pasquet, Dominique
Dumet, and Sunday Aladele—tell how they did the same almost 40
years later and came up with the same conclusions.
Restoring the IITA forest 33
The IITA forest is an Important Bird Area, refuge, and a critical
pocket of biodiversity in Nigeria and in the region. Read how the
IITA-Leventis forest restoration project in Ibadan is promoting and
raising awareness about forest conservation.
36 BEST PRacTicE
Investing in aflasafeTM 36
Commercial production of a simple biocontrol product called
aflasafe™, developed by IITA and collaborators, may be the
solution to the recalcitrant problem of aflatoxin contamination in
important food products, such as maize and groundnuts.

3. Clean seed systems: banana, cassava, and yam Clean yam seed tubers from vine cuttings 43
Production and distribution of clean planting materials Plant Physiologist Hidehiko kikuno describes the
of banana and plantain 38 new technology of producing yam seed tubers.
Banana is a staple eaten by millions of Africans. in this The technology combines growing vine cuttings on
article, Banana/Plantain Breeder Bi irie Vroh explains carbonized rice husks and in vitro micropropagation
how iiTA produces clean planting materials of banana (tissue culture). it is quick, cost-effective and results
for distribution to partners. in clean planting materials.
Developing clean seed A hot bath for the suckers! 46
systems for cassava 41 Production of banana and
Cassava is the most widely plantain, important food crops,
cultivated of all vegetatively- is constrained by pests and
propagated crops. Virologist diseases, such as nematodes
James legg discusses how and weevils that lead to annual
iiTA and partners have put in losses of millions of dollars. iiTA
place a rigorous new system scientists have devised an easy
called Quality Management method of killing nematodes in
Protocol to assure the health banana suckers—immersing
of cassava planting material. them in boiling water for 20-30
seconds!
48 DEWN: adiseasesurveillance system for
cassava
novel
48
A multipartner team of scientists have
tool box
developed an early warning system that uses
cell phones to monitor and track cassava
disease outbreaks in Tanzania, and now in
Rwanda.
54 who’s who 59 lookiNg iN
David Chikoye: NAQS: iiTA contributes to our effectiveness 59
Think of the big picture 54
CoMESA: Ensuring sanitary and phtosanitary
Jim gockowski: standards in the region 62
Intensification of agriculture is an
alternative to deforestation 56 iAPSC: Protecting Africa's plant health 66
70 f R o N T i E R S
Transgenic banana for Africa 70
Molecular geneticist leena Tripathi provides an update on
a collaborative work to develop a high-value product—the
transgenic banana. The use of transgenic technologies
facilitates the transfer of useful genes, such as those for
developing resistance to banana Xanthomonas wilt.
1

4. EDiToR'S NoTE
Plant health matters
Efforts by national and international intensification2. The compelling reason
research systems during the last two for this is that biological threats, such as
decades have contributed to nearly diseases, pests, and weeds are directly
doubling the production of major staple responsible for reducing crop yields by
foods including cassava, maize, yam, at least one-third3, and at least half of
and banana in Africa. Most of these these losses could easily be averted
gains, however, have come about as a using simple and affordable technologies
result of an expansion of the planted and practices that prevent diseases and
area, but crop production per unit area pests from affecting plants and produce.
of the land is lower than anywhere else Ensuring plant health, therefore, is one
in the world. of IITA’s most important R4D strategies
to improve agricultural productivity and
Yet the continent is expected to improve
food security and reduce poverty.
food production dramatically, doubling
or tripling the existing capacity, to This issue highlights some of the
feed over 200 million undernourished technologies and strategies developed
people1. Although new varieties have and promoted by IITA and its partners
contributed to improve crop production, for plant health protection.
productivity, and quality, their
The value of plant health management
performance has been constrained by
cannot be underestimated given
suboptimal conditions, such as declining
the precarious nature of agricultural
soil fertility, drought, attacks by pests
systems in Africa with the evolution,
and diseases, and lack of good quality
establishment, and quick spread of
planting material.
pests and diseases, such as fruit flies,
The current approach—expanding the cassava brown streak and banana
area under agriculture to increase food bacterial wilt.
production—is unsustainable and results
Although plant health protection
in significant ecological damage. This
measures are relatively easy to adopt,
realization worldwide is driving the
considerable training, awareness
search for newer options to intensify
creation, and financial support
agriculture within the existing area.
are required to improve skills and
We believe that ensuring plant health infrastructure in national systems to
is pivotal to increase productivity and foster the technology transfer to farms
the strategy of sustainable agriculture where plant health matters.
True national defense is a huge offensive force
against biological threats to food systems.
- Hartmann, Director General, IITA
1
FAO. 2010. The State of Food Insecurity in the World 2010. FAO, Rome.
2
www.bis.gsi.gov.uk/foresight
3
Oerke EC. 2006. J. Ag. Sci. 144: 31–43.
2

5. To ensure food security in Africa, plant health matters need to be given immediate
attention. Photo by J. Oliver, IITA.
3

6. NEWS The varieties are Tgx1740-
2f, Tgx1987-10f, and
Tgx1987-62f. Tgx1740-
2f was developed by iiTA
High in nutritive value,
soybean is fast gaining
appeal in Africa, offering a
cheap source of protein. The
Nigeria gets in collaboration with the crop is also emerging as an
improved Department of Agricultural
Research Services (DARS) in
important feed, food, and
raw material for producing
cassava Malawi. Varieties Tgx1987- high-quality protein products.
10f and Tgx1987-62f for smallholder farmers it is
The Nigerian government were developed by iiTA in an important cash crop and
has released four improved collaboration with Nigeria’s also improves soil fertility
cassava varieties that are a NCRi. because of its ability to fix
product of about a decade- high amounts of atmospheric
old conventional breeding The Malawi Agricultural
Technology Clearing nitrogen.
research. These include NR
01/0004, CR 41-10, TMS Committee officially approved
the release of Tgx1740-2f
00/0203, and TMS 01/0040.
in January 2011 while the Conference on
TMS 00/0203 and TMS
01/0040 were bred by iiTA
Nigeria Varietal Release humid tropics
Committee released
scientists, while NR 01/0004 Tgx1987-10f and Tgx1987- The Consortium for improving
was bred by the Umudike, 62f in December 2010. Agriculture-based livelihoods
Nigeria-based National Root in Central Africa (CiAlCA)
Crops Research institute, and The varieties outperformed
the standard and local checks and the CgiAR Consortium
CR 41-10 by the Colombia- Research Program (CRP) on
based international Center for grown in the two countries,
with high grain yield in the Humid Tropics led by iiTA
Tropical Agriculture (CiAT). will convene an international
multiple locations under on-
on-farm prerelease trials station and on-farm trials. conference on 'Challenges
involving local farmers in eight and opportunities for
states of the country show Many farmers preferred Agricultural Intensification of
that the improved varieties the varieties because they the Humid-Highland Systems
outperformed local checks smother weeds and reduce of sub-Saharan Africa', in
with an average yield of about the cost of weeding. farmers kigali, Rwanda, on 24-27
31 t/ha compared with 26 t/ that participated in the on- october 2011.
ha recorded by the local farm trials of the varieties last
year said they preferred them The humid highlands in
varieties. sub-Saharan Africa are
especially for their golden
farmers love the varieties color at maturity. characterized by high
for their excellent culinary population densities and
qualities, high yield, and in Malawi, Tgx1740-2f require intensification.
resistance to pests and gave the highest mean Unfortunately, many
diseases. grain yield of 2.5 t/ha. it communities lack easy
exceeded the yield of checks, access to the means to
The new varieties seek to grain variety Nasoko by achieve this.
strengthen Nigeria’s lead in 10% and the widely grown
cassava production, increase promiscuous variety Magoye The conference aims to take
farmers’ incomes, and by 32% during the two-year stock of the state-of the art in
guarantee food security. multilocation on-station trials. agricultural intensification in
the highlands of sub-Sahraran
The variety performed Africa, and to chart the
Better soybean equally well during on-farm
participatory variety selection
Two African nations—Malawi trials in four districts of central
and Nigeria—have released Malawi. in the 2009/10
three improved soybean season, it outyielded all
varieties that can enhance the new types of soybean
the productivity of the crop varieties under testing with
and offer farmers better 2.2 t/ha. it also surpassed
opportunities. Nasoko by 15% and Magoye
by 38%.
4

7. way forward for agricultural
research for development in Liberia and
the humid highlands, through Ghana to develop
keynote presentations, oral
and poster presentations, and agriculture
strategic panel discussions.
The governments of ghana
UPoCA gives and the Republic of liberia
have officially agreed to
farmers a lifeline jointly develop, promote, and
implement research activities
Cassava value addition to improve their agricultural
is helping African farmers sectors.
increase their income, and
improve livelihoods and A memorandum of
food security through a understanding was signed by
USAiD-funded project called Happy cassava woman representatives of ghana and
Unleashing the Power of farmer. Photo by IITA. liberia, with the assistance
Cassava (UPoCA). of iiTA’s Sustainable Tree
farmers benefited from Crops Program (STCP), in
implemented in seven improved cassava cuttings, collaboration with the ghana
African countries—Nigeria, training, and capacity building Cocoa Board. iiTA/STCP
DR Congo, ghana, Malawi, for processors. works in both countries.
Mozambique, Tanzania, in Nigeria the project linked
and Sierra leone—by iiTA, The agreement was signed
up processors to farmers for by the Minister of finance and
the project has benefited steady production/supply
thousands of farmers in these Economic Planning, kwabena
of cassava roots, provided Duffuor, and the Chief
countries. improved cuttings and Executive of CoCoBoD,
in Sierra leone, the training, and also helped build Anthony Fofie, for Ghana, and
Tongea Women farmers the capacities of farmers and by the Minister of Agriculture,
in Sandeyalu community processors. florence Chenoweth, and
formed the Tongea women's farmers in ido community, the Deputy Director general
development association oyo State, Nigeria, have of the Central Agricultural
comprised of 54 women and more than doubled the yield Research institute (CARi),
4 men. of cassava from an average Abugarshall kai on behalf of
Through the iiTA-UPoCA of 10 t/ha to more than liberia.
project, a cassava 20 t/ha. other states that Under the MoU, the Cocoa
microprocessing center was benefited from the UPoCA Research institute of
subsequently inaugurated, project were osun, ondo, ghana and liberia’s CARi
providing farmers with Ekiti, kogi, Nasarawa, and will exchange expertise,
a financial window of Benue states. knowledge, and genetic
opportunity. incomes from farmers say the project has resources (seeds and nursery
USAiD projects such as increased the production of development) to develop and
UPoCA have helped the cassava with the availability improve the tree crops sector
people of Sandeyalu in of improved cassava stems, in Liberia. Specifically, the
rebuilding their community making food more secure and national research institutions
after years of civil unrest. generating wealth. of both countries will facilitate
This success story echoes the provision of planting
Apart from boosting the material as requested by
across other countries such productivity of cassava in the
as Nigeria, DR Congo, either countries, make
project areas and maximizing available research and
ghana, Malawi, Mozambique, the use of the root crop, the
and Tanzania where UPoCA training facilities and materials
project is also promoting food to visiting scientists from
is being implemented. security and improving the either institution, and provide
in Malawi, UPoCA helped incomes of women farmers technical expertise for the
revive a moribund starch and processors in particular, successful implementation of
factory—the first in that and African farmers in mutually-agreed projects.
country. Thousands of general.
5

8. Climate change
plant health
&
Irmgard Hoeschle-Zeledon*, i.zeledon@cgiar.org or sp-ipm@cgiar.org
The discussion on the impact of climate technologies (e.g., predictive models,
change (CC) on agriculture has often diagnostic tools) that are suitable for
focused on how changes in temperature, diverse agroecologies including the
rainfall, and CO2 concentrations will tropics, wet, humid, semiarid, and dry,
affect the suitability of temperate and to some extent the temperate
regions for crop production and how zones as well. The broad knowledge
crops will react in terms of yields. The and experience of centers provide an
effects of climate change on biotic unprecedented advantage to assess the
factors in the tropics, such as weeds, products and technologies in different
pests, and pathogens (hereafter agroecologies and weather settings and
referred to as pests), have not received to determine their resilience and ability
much attention. to cope in altered climatic situations.
Empirical data exist, however, to show Several programs directly focus on
that these biotic factors have major managing pests. For instance, the
effects in determining productivity in breeding of crop varieties for resistance
the tropics. For instance, during the to pests and pathogens has always
1997 El Niño phenomenon, the mean been a focus of the CGIAR. With the
temperature on the Peruvian coast uncertainties of CC, this work has
increased by about 5 °C above the become more relevant. Breeding for
annual average, causing a decrease resistance to drought and waterlogging,
in potato infestation by the leafminer although not the primary objectives,
fly Liriomyza hydobrensis, which also aim at making varieties better
otherwise was a major pest. However, able to tolerate biotic threats, since
the abundance and infestation severity drought and excess water in the soil
of all other pests increased in all crops, both increase the plants’ vulnerability to
including potato (Kroschel et al. 2010). these factors.
The complex consequences of CC
particularly on pests and pathogens A good example is the effort to develop
are still only imperfectly understood drought-resistant maize cultivars
(Gregory et al. 2009). by CIMMYT and IITA. These will not
only allow the expansion of maize
CGIAR’s work on climate change production into areas with less reliable
What are IITA and the other centers of rainfalls but also ensure the continued
the Consultative Group on International production in regions that are prone
Agricultural Research (CGIAR) doing to future water scarcity. Drought-
to mitigate the impacts and adapt to tolerant cultivars also reduce the risk
the effects of CC on pests? Historically, of aflatoxin contamination in the field.
CGIAR centers have a broad R4D Additional characters are incorporated
focus; centers have been developing into the drought-tolerant maize, such as
knowledge (e.g., pest profiles), products resistance to maize streak disease which
(e.g., new crop varieties, biocontrol is endemic in Africa. Similar programs
agents against invasive pests), and are ongoing to develop drought-resilient
*Coordinator of the CGIAR Systemwide Program on Integrated Pest Management (SP-IPM)
convened by IITA.
6

9. cassava and cowpea, and yam with the distribution of the species due to
tolerance for major pests. increasing temperatures. The approach
can also be used for other insect
The CGIAR centers are also working species. Hence, CIP created the Insect
towards the development of cropping Life Cycle Modeling software (ILCYM)
systems with greater intra- and to facilitate the development of other
interspecific diversity to increase insect phenology models. With its
resilience to CC-induced threats from support, the phenology model can be
biotic factors. For example, IITA is implemented and allows for spatial
promoting maize–cowpea intercropping simulation of insect activities.
to reduce the pest pressure on cowpea.
Many centers support the collection
Bioversity International is exploring and conservation of plant genetic
how intra-specific crop genetic diversity diversity that can be built into new
on-farm not only reduces current cultivars to enhance their resistance
crop losses to pests and pathogens, to biotic stresses. Diagnostics capacity
but also decreases the risk of genetic is continuously augmented for the
vulnerability and the potential of accurate and timely recognition of
future crop damage, thus enhancing endemic pests, new variants, and
the impact of other IPM strategies invasive pests. Crop biodiversity—
and providing farmers with increased landraces and wild relatives that are the
adaptive capacity to buffer against reservoirs of genes for abiotic and biotic
climatic changes. factors—is conserved ex situ to protect
the species from erosion by CC-induced
CIP developed a temperature-driven
changes.
phenology model for the potato tuber
moth, Phthorimaea operculella that In a collaborative effort, CIP, IITA, icipe,
provides good predictions for the and partners in Germany and Africa are
population in areas where the pest implementing a project to understand
exists at present (Kroschel et al. 2010). the effects of rising temperatures on the
Linked with geographic information distribution and severity of major insect
systems (GIS) and atmospheric pests on main food crops. ILCYM will be
temperature, the model allows the further improved and adapted to cover a
simulation of risk indices on a worldwide wide range of insect species. The results
scale to predict future changes in will contribute to filling the knowledge
Diverse crop production system. Photo by IITA.
7

10. gap about CC effects on economically streak, soybean rust, and pod borer
important insect herbivores and their pests, among others.
natural enemies.
As whiteflies and aphids are considered
IITA is planning to research the effect of to become more problematic with
changes in temperature on the invasion increased temperatures, IITA is also
potential of major biotic threats in the preparing research on the biocontrol of
Great Lakes region of East Africa and different whitefly and aphid species in
elsewhere: Banana bunchy top virus vegetables and staple crops.
(BBTV), Banana Xanthomonas Wilt
(BXW), and Panama Disease–Tropical A project has been proposed on
Race 4, cassava brown streak virus the bio-enhancement of seeds and
disease, cassava mosaic disease, maize seedlings of cereals and vegetables
A
B
Climate change scenarios for the potato tuber moth, Phthorimaea operculella: (A)
Generation index (generations/year) under present temperature conditions, and
(B) Change in numbers of generations/year by 2050 using the atmospheric general
circulation model (Govindasamy et al. 2003).
8

11. for East Africa to stimulate the plants’ In collaboration with CABI, community
defense mechanisms against pests surveillance for pests and diseases will
and pathogens expected to increase in take place through the expansion of the
number, frequency, and severity. This mobile plant clinic network.
project also addresses the registration
of biopesticides and the availability Knowledge and decision support
of endophytes to the tissue culture tools for the management of potato
industry. and sweetpotato pests (diseases
and insects) will be developed and
CGIAR research programs assessed in relation to the expected
Under the new CGIAR Research intensification of the agroecosystems in
Programs (CRPs), centers are the humid and subhumid tropics.
addressing CC-induced crop health
issues in various ways. Breeding Sustainable management of cassava
for resistance to predicted biotic virus disease in the cassava-based
stresses continues to be a major system will also be studied, and the
focus in CRP3 (roots, tubers, vulnerabilities of these systems to CC-
banana) and its subcomponents. induced pest and disease problems will
This component, coordinated by be determined.
CIP, specifically recognizes CC and The CIAT-coordinated CRP on CC,
agricultural intensification as drivers Agriculture, and Food Security began
for higher pressure from pests. Hence, operations this year. It will continue
this program aims at developing the activities initiated by the CGIAR
management strategies for priority Challenge Program on CC. This CRP
biotic threats to these crops. These aims at mainstreaming strategies
include the development of improved that address the management of CC-
detection and monitoring tools, and induced pest and disease threats among
surveillance methods for detecting international and national agencies. It
and mapping existing, emerging, will identify and test innovations that
and resurgent molecular pests and enable communities to better manage
pathogens. It will look into increasing and adapt to climate-related risks from
general plant and root health through biotic factors.
the enhancement of the natural disease
suppressing potential of soils, and the Recommendations
antagonistic pest and disease potential A lot of surprise shifts in ecosystems
of the aboveground agroecosystems. could come. It is therefore important
that research capacity and knowledge
The CRP on Integrated Systems for the bases are maintained to understand and
Humid Tropics, led by IITA, will have rapidly react to mitigate any debilitating
a substantial focus on CC, its impact impacts (Shaw and Osborne 2011).
on pests, and plans for mitigation.
For example, research will establish To accomplish this, it is necessary
the relationship between CC and key to establish good baseline data on
cassava pests to develop integrated pest current pest status in agroecosystems.
management (IPM) strategies including This knowledge base will serve as
those for whitefly, African root and tuber a reference point to measure the
scale, termite, green mite, aphid, and fluctuations and the effectiveness of
mealybug. interventions.
Phenology models for insect and mite It is important to determine the key
pests and their antagonists on several weather variables that could change as
crops will be developed and validated a consequence of CC and their influence
and their potential for changes in on agroecosystems and pests, and
warming will be determined. establish preemptive coping strategies.
9

12. delivery systems for pest control
products (Strand 2000 in Juroszek and
Tiedemann 2011). Preventive crop
protection measures may become more
relevant under CC to reduce the risks
(Juroszek and Tiedemann 2011).
CC is a global problem that affects all
countries. Hence, global cooperation is
required. However, given the nature of
plant pests and pathogens, more local
Larva of the noctuid moth feeding on the or regional strategies need to be put
pistil of cowpea. Photo by S. Muranaka, IITA. in place that define potential risks and
measures to tackle expected threats.
Available CC models could be handy for Investments in early detection systems,
predicting CC factors. including border controls to monitor
the migration of pests through plants,
A diverse scientific base including plant products, and other goods, will be
specialists in pathology, entomology, the key to avoid the spread of invasive
ecology, taxonomy, and epidemiology pests and reduce high management and
is required. They should work together eradication costs (FAO).
to ensure that the outcomes of
their research are linked to existing New farming practices, different
knowledge, economic forces, and crops, and IPM technologies must be
common understanding (Shaw and developed to control the established
Osborne 2011). pests and prevent the spread of new
ones (FAO).
As it generally takes more than 10 years
to breed a new resistant cultivar of a Governments should consider
crop, breeding programs must start well developing country-specific strategies
in advance of the serious risk of a biotic to cope with CC-induced changes and
threat Breeders need to be informed put in place favorable policies for the
on the problems which might become introduction and promotion of new
important in the future (Chakraborty technologies for CHM.
et al. 1998 in Juroszek and Tiedemann It is also crucial to create and augment
2011). awareness about the effects of CC
Crops being bred for abiotic threats such among policymakers and other officials
as drought, waterlogging, and salinity involved in developing agricultural
should be prepared for the pests that strategies.
could flourish under these conditions References
and select varieties that can tolerate Chakraborty S and Newton AC. 2011. Plant
pests as well. Pathology 60: 2-14.
FAO. unknown. ftp://ftp.fao.org/docrep/fao/010/
Changes in occurrence, prevalence, and i0142e/i0142e06.pdf
severity of infections and infestations Govindasamy B et al. 2003. Climate Dynamics
will also affect crop health management 21: 391-404.
(CHM) practices. There is a need to Gregory PJ et al. 2009. Journal of Experimental
effectively disseminate and use those Botany 60: 2827-2838.
techniques that are currently underused Juroszek P and von Tiedemann A. 2011. Plant
(Juroszek and Tiedemann 2011). Pathology 60: 100-112.
Kroschel J et al. 2010. http://www.spipm.cgiar.
Significant contributions could be org/ipm-research-briefs
made in improved field monitoring Shaw MW and Osborne TM. 2011. Plant
of pests and diseases, and better Pathology 60: 31-43.
10

13. Climate change is everyone’s responsibility
Climate change (CC) is a variations in climate (e.g., Using simulation models,
long-term change in the permanent increase in attempts the world
statistical distribution of average temperature) that over are being made to
global weather patterns might irreversibly affect determine the impact of
over periods of time that biodiversity in a given CC on agroecosystems to
range from decades to region. establish appropriate coping
millions of years. Several strategies, particularly
In the context of
factors, known as climate for the negative impacts.
agriculture, sudden and
forcers, usually natural Although this appears
abnormal changes in
events such as volcanic simple, it is the most
weather could change
eruptions, earthquakes, complex issue confronting
the suitability of a given
solar radiation, and ocean researchers, policymakers,
environment for cultivation
currents shape climate governments, and
of crops. This could be due
change. entrepreneurs worldwide.
to abiotic factors such as
However, the climate forcer drought, heat (cold), or Communities are working
of the 21st century CC— excessive water directly together to bridge the
carbon dioxide (CO2)—is linked to weather or gaps and establish global
mainly human-induced and simply due to increased coordination networks to
attributed to the burning pests and diseases that mitigate the impact of
of fossil fuels and tropical would severely impede CC. IITA and other CGIAR
deforestation. The property performance of the crops. centers, together with
of CO2 to trap heat within Since crops, diseases national and international
the earth’s atmosphere (pathogens), and pests organizations, are
is contributing to global (including vectors) are contributing to these
warming. Thus, a rise in intimately associated endeavors with a primary
CO2 levels increases the and influenced by the focus on conserving
warming effect. Trapped environment, any shift in biodiversity and improving
heat in the atmosphere these factors will alter the the resilience of
warms oceans, melts ice balance, and could have smallholder agriculture in
caps, raises sea levels, a positive impact (e.g., the developing countries
and increases average decreased pest pressure) in Africa, Asia, and Latin
surface temperature, all of or negative impact (e.g., America.
which are affecting normal increased pest pressure) on
weather patterns. overall crop performance.
Some of the abnormal
changes experienced
over the last two decades
include severe and
prolonged droughts,
extreme storms and
prolonged rainfall pattern,
high temperatures, and
heat waves. These sudden
and extreme variations
in weather patterns due
to ‘global warming’ have
profound effects on living
organisms on earth.
The altered conditions
create risks as well as
opportunities favoring Life on earth is a dynamic process and intimately
certain living beings over connected to the biotic forms in cohabitation, farming
others and contribute to systems, and environment. A shift in one parameter
shifts in niches. In addition, alters the delicate balance in an interconnected world.
it could lead to long-term Source: L. Kumar, IITA.
11

14. fEATURES
Towards a healthy banana
TC industry in East Africa
Thomas Dubois, t.dubois@cgiar.org
Tissue culture banana modified banana. In other words, the TC
Banana in smallholder farmer systems technology can help banana farmers to
is traditionally propagated by means make the transition from subsistence to
of suckers. These contain soil-borne income generation.
pests and diseases, and by using them, However, TC plantlets are relatively
farmers unknowingly distribute and fragile and require appropriate
perpetuate pest and disease problems. management practices to fully harness
their potential, especially during the
Plants produced by tissue culture (TC),
initial growth stages shortly after being
because they are produced axenically
transplanted to the field. In East Africa,
in the laboratory, are material that is
TC plantlets are often planted in fields
free from pests and diseases with the
burdened with biotic pest pressures and
exception of fastidious bacteria and abiotic constraints.
viruses.
A SWOT analysis
There are many added benefits to The importance of the private sector
using TC plants: (1) they are more The adoption of TC technology is still
vigorous, allowing for faster and relatively low in East Africa. In Kenya,
superior yields; (2) more uniform, coverage of TC banana is estimated
allowing for better marketing; and (3) at 5–7% of the total banana acreage;
can be produced in huge quantities in adoption rates are significantly lower in
short periods of time, allowing for faster countries such as Uganda, Burundi, and
and better distribution of existing and Tanzania, although reliable data do not
new cultivars, including genetically exist.
Young tissue culture plantation in Nairobi, Kenya. Photo by T. Dubois, IITA.
12

15. (t/ha/cycle)
60
50 tissue culture
suckers
40
30
20
10
0
low input high input
Cumulative yield (t/ha/cycle) of a plantation derived from tissue culture (orange bars)
compared to one derived from conventional planting material (blue bars), over 5
cropping cycles and under two management regimes (low input and high input). Every
little block represents one crop cycle. Data based on 1,600 plants total.
In East Africa, the technology is during the production process, (2) plant
booming under the impetus from the health certification, and (3) regulatory
private sector. At least 10 commercial procedures. Such conditions are
private laboratories have sprung up especially important to avoid spread of
in the last decade in Burundi, Kenya, viruses, which are easily transmitted
Uganda, and Tanzania. Collectively, through TC plantlets.
they produce at least 2 million plants/
year, although exact numbers seem to For instance, Banana bunchy top virus
fluctuate widely and are hard to come (BBTV) is on the list of the 100 most
by. Most of these companies manage dangerous invasive species worldwide.
the entire production chain, from It is widely distributed in Central Africa
sourcing the mother plants to weaning and also in Burundi and Rwanda in
the TC plantlets. Despite the steep entry East Africa, yet implementation of virus
barrier, the TC business is very lucrative indexing schemes is largely absent in
for the entrepreneur who engages in East Africa. It is important to put in
plantlet production. In some countries, place standard procedures for ensuring
universities and research organizations the production and distribution of high-
are also involved in the commercial quality, virus-free planting material,
production of TC banana. and to establish independent agencies
that set and implement standards and
Lack of quality standards and virus improve the skills of personnel. In East
indexing Africa, certification schemes need to be
One of the biggest dangers for regionally harmonized, especially with
sustainable commercial production of TC the transnational movement of plants
plants is the lack of several essentials: between the countries, so that there is
(1) standards for quality management no weak link in the region.
13

16. Unregulation—a potential danger to the Another important requirement for
spread of diseases TC producers is sustainable access to
At present, the commercial production virus-free and true-to-type mother
of TC banana plantlets is largely plants and this is currently lacking.
unregulated. Not only are TC banana The establishment of certified mother
plantlets being moved in very large plant gardens as a common resource,
quantities across borders; uncertified either by governmental agencies
mother material is also crossing or a consortium of commercial TC
borders. This practice is potentially producers, would provide this essential
risky, and could perpetuate infected requirement.
sources and cause new outbreaks of
disease. Contrary to a general perception,
especially among donors, it is not
In the ideal situation, there need merely the standards themselves
to be certification standards for the that are a constraint, but also a lack
quality and health of TC plants and the of knowledge on how procedures are
monitoring of TC producer operations. actually implemented along the value
These are largely ignored because chain, through certification schemes.
of poor awareness, and the lack of The equipment for virus indexing has
capacity and regulations required for become relatively cheap and technical
the implementation of such standards. skills are quite easily acquired. Their
To transform the system, governments costs can be offset, e.g., through a
and/or the TC industry could consider service-based fee to private sector
common facilities to implement stakeholders.
certification schemes. For instance, an
accredited governmental or independent Also, emphasis could equally be placed
virus indexing laboratory, established as on certifying general operational
a commercial service for TC operators, procedures in a private TC laboratory.
would leverage costs and improve TC Currently, the quality of TC plantlets
standards. varies significantly, and several
producers are struggling with off-types
and accidental mixtures of varieties
that become apparent only after being
planted in the field, resulting in negative
perceptions about TC.
Certification schemes need to be
implemented in such a way that they do
not become burdensome to producers
or create bureaucratic barriers. Several
quality certification schemes used for
clonal crops, including banana, from
other regions can be considered to
develop an appropriate scheme for
East Africa. Ultimately, it is not only
the commercial sector that should self-
regulate; governmental bodies need to
take responsibility.
Nurseries
Nurseries for TC plants are essential, as
they act as a distribution hub connecting
producers to the farmers. They also
Plantain for sale in market. Photo by IITA.
act as focus centers for farmers and
14

17. farmers’ groups, and are therefore an
easily approachable venue for training Test tubes to farms: how it’s done
and other interventions. The survey
by IITA and University of Hohenheim Tissue culture plantlets are made
of all TC nurseries in Burundi, Kenya, in specialized laboratories, and the
and Uganda, found that nurseries in technology consists of a few basic
East Africa face an array of problems. steps: (1) the apical meristem is
Relationships between producers and isolated from the mother plant and
nurseries, especially those related to induced to form shoots, (2) the shoots
timing, quality, and quantity of plantlet are multiplied, (3) when plants are
supply, are often suboptimal. needed, the multiplied shoots are
put on a root-inducing medium, (4)
At the nursery level, there are three the young plants are transferred to a
main operational issues: access to screenhouse for hardening, and (5) the
water, credit, and the transport of plants are planted in farmers’ fields.
plantlets. The location of the nurseries
is also crucial. Nurseries need to be
close to the producer and to the market,
otherwise they might fail. Clear drivers is subsidized. Virtually all TC plantlets
for the success of a nursery are good are being bought by developmental
agricultural practices and, interestingly, agencies, which then pass on these
a diversification into crops outside plantlets to often untrained farmers,
banana. free of charge, and without embedding
this transfer in an encompassing
In TC banana value chains, nurseries training program or input package (e.g.,
have different roles across countries in fertilizers).
East Africa. In Uganda, nurseries are
run as businesses independent of the Empowerment of farmers in the value
TC operators and of the farmers. In chain through farmers’ groups
Burundi, the nurseries are owned and Organizing banana farmers into groups
managed by the producers. In Kenya, has long been considered advantageous,
nurseries are run as entities separate because of increased buying and selling
from the producers, and most of them power, reduced economic and social
are owned by farmers’ groups that act risk, increased economies of scale, and
as the customers for these nurseries. improved access to credit and inputs by
The business model in Kenya seems to formally certified groups.
hold the secret for a sustainable and
vigorous link between producers and The study by IITA and the University
farmers. of Hohenheim of the farmer-to-market
linkage in Uganda demonstrated that
Distorted value chains farmers in marketing groups obtain
One danger for a healthy commercial higher prices than their ungrouped
TC sector is the lack of sustainable colleagues. The certification of farmers’
market pathways to deliver the plants
groups implemented by IITA’s national
to the farmers. Especially in Burundi
partners, ISABU (L'Institut des Sciences
and Uganda, outlet markets for TC
Agronomiques du Burundi) in Burundi
plantlets are mainly governmental
and VEDCO (Volunteer Efforts and
and nongovernmental organizations, a
Development Concerns) in Uganda,
situation which seems unsustainable in
the long term. has made them eligible for savings
and credit schemes. Some have even
The sustainability of the banana TC engaged in other commercial activities,
industry is especially worrisome in such as the start-up of a catering
Burundi, where the entire value chain service.
15

18. Training of farmers' group in business skills in Uganda. Photo by Moses Lule.
The importance of a training package training program was monitored. So far,
In East Africa, the distribution of a total of 851 separate training events
superior planting material alone will have been implemented in Burundi,
not ensure a good crop. Commercial Kenya, and Uganda, and through the
farmers are skilled in juggling the partnership, 10 new farmers’ groups
inputs and effort needed to produce and 5 new nurseries have been
crops and make a profit but smallholder established.
farmers are constrained by factors such
as a lack of land and capital, access Location, location, location
to technology, and a good marketing TC banana plantlets come at a cost, and
infrastructure. Therefore, efficient might not be economically beneficial
distribution systems will be needed throughout all banana-producing areas
to deliver the TC plants as part of a in East Africa. Location is everything.
package, including training and access
to microcredit. IITA, in collaboration with Makerere
University, conducted a cost-benefit
IITA and its national partners, ISABU, analysis of the technology based
JKUAT (Jomo Kenyatta University on a comprehensive quantitative
of Agriculture and Technology), and questionnaire with 240 farmers across
VEDCO, have been implementing hands- four districts in Uganda, and compared
on, comprehensive training schemes it with the use of conventional planting
for farmers as well as the operators of material.
TC banana nurseries. Training schemes
encompass modules in agronomy, Both production costs and revenues
marketing, business and financing, and were consistently higher for TC-derived
for farmers, group formation and group material than for suckers. However,
dynamics. Participants were followed banana prices varied greatly with
for over a year, and their ability to district and declined significantly with
implement the skills learned during the increasing distance from the main
16

19. market (see graph). Also, production Sound socioeconomic analyses are
costs decreased significantly the further crucial to guide policy strategies, learn
away the farms were from Kampala due from successes already achieved, and
to better agroecological conditions and identify important constraints for a
the much reduced pressure from pests wider dissemination of TC banana in the
and diseases. As a result, although both region.
TC plantlets and suckers were profitable
to the farmer, TC material was more Earlier studies on the impacts of TC
profitable than suckers closer to the banana in the region have either
main banana market. employed ex ante methods before
any meaningful adoption was actually
In districts with low banana prices and observable, or they have used
at a greater distance from the main relatively simple and ad hoc qualitative
banana market, farmers could receive methodological tools, which do not allow
similar gains by planting suckers rather robust and representative statements.
than TC plants. For a farmer in Uganda, The large body of subjective ‘gray’
it makes economical sense to grow TC literature, sometimes unconditionally
banana close to the main urban market.
and unilaterally promoting the benefits
An objective ex-post assessment of TC banana, without considering
Despite a booming commercial sector, the quality of the plant material,
there is only anecdotal evidence that input package, and market access,
farmers who have adopted TC banana risks having an adverse effect on the
benefit tremendously in terms of adoption of the technology in the
higher yields and household incomes. long term.
gross margins (Ugsh/ha/year)
7,000,000 tissue culture
suckers
6,000,000
5,000,000
4,000,000
3,000,000
2,000,000
1,000,000
0
Luwero Mukono Masaka Rukungiri
10 km further away from the market 350 km
Gross margins (in Ugandan shillings)/ha/year of banana plantations derived from tissue
culture (yellow bars) compared to conventional planting material (orange bars) in
Uganda, the further away from the main banana market (Kampala).
17

20. The University of Göttingen, in and requirements. This study finds
collaboration with IITA, is currently that farmers’ education, access to
answering the following main agricultural information, knowledge of
research questions: (1) What are the the location of a TC nursery within a
determinants of TC banana adoption reasonable distance, and affiliation to
among farmers? (2) What are the social groups significantly increase the
impacts of this technology on on-farm likelihood of the TC technology being
productivity, household income and adopted.
income distribution, and poverty and
food security? (3) How do institutional This study also highlights the positive
factors in technology delivery and role of access to credit and of gender
product marketing influence adoption in the adoption of TC material. Farmers
and impact? with access to credit and female-headed
households are more likely to adopt TC
Some of these research questions have plants. The latter finding is particularly
been answered. In Kenya, a substantial interesting from a policy perspective,
share of the population has heard about because it shows that, when there is an
TC banana and is, therefore, generally equal chance for both men and women
aware of the technology’s existence, to acquire sufficient knowledge about
although only a few have had a chance an innovation, women are more likely to
to fully understand its performance adopt it.
Banana market in Ikire, Nigeria. Photo by O. Adebayo, IITA.
18

21. GHU: Gateway for the safe
exchange of germplasm
Lava Kumar, l.kumar@cgiar.org
International exchange of germplasm:
an essential step for sharing
international public goods
Since its inception in 1967, IITA has
been actively involved in the collection,
conservation, and use of the plant
genetic resources of important crops,
such as banana and plantain, cassava,
cowpea, maize, soybean, and yam,
and their wild relatives from Africa and
other parts of the world. Using this
germplasm, IITA’s crop improvement
programs, based in several locations
in sub-Saharan Africa, have been Seed testing. Photo by IITA.
developing high-yielding, nutritionally
Germplasm exchange: benefits and risks
Crop germplasm—seeds, has an inherent risk of in 1993. The accidental
plants, or plant parts introducing exotic plant introduction of the Banana
suitable for propagation— pathogens (viruses, fungi, bunchy top virus in Malawi
is a high-value commodity bacteria, phytoplasma, has affected banana
very frequently exchanged and other pathogenic production in over 3000
for agricultural research, microbes), weeds, insects, ha and completely wiped
crop diversification, and nematodes (pests). out production in Nkhota
food production, and Due to a lack of competition Khota and Nkhatabay. In
commerce. International and resistance, introduced addition, pests associated
exchanges of useful pests often result in with the germplasm
germplasm have been devastating epidemics in may reduce its longevity
the major factor in territories in which they did during storage and may
the diversification and not exist before, leading have negative effects
improvement of global to severe economic losses. on crop performance
agriculture. For instance, The cassava green mite, (e.g., nematodes in
about 30% of the world’s Mononychellus tanajoa, a yam tubers). Therefore,
food production is derived native of Latin America, several safeguards
from crops originating was accidentally introduced have been established
in other countries. into Africa in the 1970s to prevent the spread
Cassava, first introduced and spread to almost all of pests through the
from Latin America by the cassava-producing movement of germplasm
the Portuguese in 1558, regions, reducing yields from one area to another.
has been established as by 30−50%. This pest These quarantine or
one of the major food was controlled through the phytosanitary measures
staples in sub-Saharan introduction of a natural are enforced through
Africa. Germplasm enemy from Latin America, national and international
exchange, however, Typhlodromalus aripo, legislation.
19

22. Scheme for phytosanitary management of germplasm. Source: L. Kumar, IITA.
superior crop varieties resistant to against the introduction of exotic pests
pests, diseases, and drought. into countries where they do not occur;
(e) ensures phytosanitary management
These are regularly exchanged with of plant genetic resources conserved
national and international programs in the IITA genebank; and (f) provides
for crop improvement and agriculture capacity building and awareness
development. creation on phytosanitary measures.
Germplasm safety matters GHU operates within the framework of
As part of the measures to prevent the the procedures for the introduction and
inadvertent spread of pests through
export of germplasm established by
exchange activities, IITA has established
the government of the host country in
a Germplasm Health Unit (GHU). The
which IITA’s operations are based. For
GHU is responsible for the production,
instance, all the exchange operations of
maintenance, and exchange of healthy
IITA’s activities in Nigeria are organized
(pest-free) germplasm in accordance
in accordance with the legislation of the
with the international requirements on
Nigerian Agriculture Quarantine Service
plant protection. These are covered
(NAQS) of the Federal Department of
by the International Plant Protection
Agriculture, Nigeria.
Convention (IPPC) under the auspices
of FAO, and those set up by the Ensuring exchange of clean germplasm
Inter-African Phytosanitary Council Crops researched at IITA comprise those
(IAPSC) and National Plant Protection propagated through botanical seeds or
Organizations (NPPOs) to safeguard true seeds (maize, soybean, cowpea,
agriculture and natural resources from and other legumes of importance
the risks associated with the entry, to African farming) and crops that
establishment, or spread of plant pests. are propagated through vegetative
propagules, including stems (e.g.,
GHU (a) facilitates germplasm exchange
cassava), tubers (e.g., yam), and in
in support of IITA’s international crop
vitro plants (e.g., banana and plantain,
improvement programs; (b) inspects
cassava, and yam).
for pests and certifies the health status
of germplasm; (c) ensures compliance Each type of germplasm demands a
with the national regulations on plant unique set of procedures for assessing
introductions and exports; (d) guards the health status of the material. At
20

23. IITA, this work goes on from production for the presence of pests. Detection
to postharvest to the point when the methods used for this purpose include
material is dispatched. visual inspection of dry seeds, seed
washing, agar and blotter tests, seed
Plant material generated for soaking, and seedling symptom tests
international exchange is inspected which aid in identifying any pest-
with the technical officers of NPPO infested material. Additional techniques
during the active growth stage in the
are used for pest identification including
field or screenhouse to ensure the
culturing techniques, microscopy, and
selection of pest-free material. The
sorted materials (seeds or vegetative biochemical analyses of samples by
propagules) are then brought to the enzyme-linked immunosorbent assay
GHU laboratories for critical inspection (ELISA), polymerase chain reaction
Seeds as vehicles of pests
True seeds (botanical seeds) offer through planting material. Therefore,
the safest form in which to exchange exchanging planting material in the
germplasm. Despite their ability to serve form of stem cuttings (e.g., cassava and
as potential vehicles for the spread of sweetpotato), tubers (e.g., yam and
pests, it is relatively easy to sort out Irish potato), or suckers (e.g., banana
contaminated seeds from healthy seeds. and plantain) poses the maximum risk
Furthermore, seeds can be treated with of spreading pests. As a general rule,
chemicals (e.g., Mancozeb at 2 g kg–1) quarantine regulations prohibit the
to eliminate several types of fungi and exchange of vegetative propagules unless
bacteria. Only a small fraction (about stocks are derived from plants certified as
10%) of the >1000 plant-infecting pest-free. Micropropagation or the in vitro
virus species is capable of being spread propagation of plants using modern tissue
through seeds (e.g.. Cowpea aphid- culture methods offers the safest option
borne mosaic virus in cowpea is seed for exchanging vegetatively propagated
transmitted, but not Cowpea golden crops. Procedures employed during in
mosaic virus). Virus infesting seeds can vitro propagation result in the elimination
be eliminated by grow-out tests, and of all pests, but not viruses and some
seeds harvested from uninfected plants fastidious microbes. Special procedures
offer the safest approach. are used to eliminate viruses from in vitro
plants. Therefore, where possible, IITA
In contrast, almost all the pests present exchanges only in vitro planting material
in the vegetative tissues (stems, tubers, (tissue culture) produced under aseptic
roots, suckers, in vitro plants) are spread conditions.
Seeds pose less risk than clonally propagated materials
Less risk High risk
-Scope for phytosanitation -Phytosanitation is difficult and demands
-Only few viruses can be special process
transmitted through seed - All types of pathogens spread
21

24. (PCR), and genomic sequencing. Only
materials that are free of the regulated Categorization of pests
and unregulated quarantine pests are
Pests are classified into (a) regulated
released for international exchange.
pests and (b) unregulated pests.
GHU also monitors for genetically Regulated pests are further classified
into quarantine pests and regulated
modified organisms (GMO) to comply
nonquarantine pests.
with the Cartagena biosafety protocol,
also under the regulation of NPPOs. This Pests whose introduction into an
is done mainly by seeking an additional area can result in severe destruction
declaration from the exporting parties are classified as quarantine pests.
on the GMO status of the planting Territories can be free of quarantine
material as stipulated in the conditions pests (e.g., Fusarium oxysporum f.
cubense Race 4 present in some parts
of the import permit issued by the of Asia but not in Africa) or present
NPPO. Diagnostic capacity exists to but not widely distributed (Cassava
monitor germplasm for traces of GMOs brown streak viruses, Xanthomonas
by PCR assays, targeting constitutive campestris pv. musacearum responsible
elements of transgene constructs, for banana bacterial wilt, and Banana
such as promoters of Agrobacterium bunchy top virus occur in Africa, but
tumefaciens or Cauliflower mosaic virus are restricted to certain regions).
35S gene, that are widely used for Quarantine pests are rigorously
generating transgenic plants. controlled through official monitoring
measures. Regulated nonquarantine
Complying with regulations pests are widely distributed and their
Germplasm exchange activity presence in germplasm causes a loss
commences with the application of of planting material or initiates a new
disease cycle (e.g., Cucumber mosaic
a permit from a host country for
virus infects a range of hosts, including
germplasm import (for use in IITA’s banana, and is widely distributed).
R4D programs) or germplasm export Regulated quarantine pests are
(to partners, collaborators and other monitored by specific procedures.
stakeholders, including IITA’s missions In general, all programs for the
in other countries). This is an essential production of clean planting materials,
process under the Convention of including those meant for international
Biological Diversity (CBD) treaty that exchanges, ensure freedom from
quarantine pests and regulated
regards biodiversity as a national
nonquarantine pests.
treasure, and requires authorization
from the respective governments The categorization of pests is usually
country-specific. For instance, NAQS
for free exchanges. Every country
classifies pests under three categories:
has a nodal agency tasked with
issuing permits for the movement of Category A: Pathogens which are
not present in Nigeria and/or in any
germplasm. country in West Africa
In addition, GHU applies for Category B: Pathogens which are of
phytosanitary certificates (PC) for the restricted local distribution in Nigeria
export of material. The PC is issued and/or West Africa against which
field inspection and or/seed health
by NPPO after the condition has been
testing methods can provide adequate
satisfied that the material being protection
exported meets the phytosanitary
Category C: Internationally widespread
standards of the IPPC and the importing
pathogens which affect seed quality.
country. GHU invariably complies with
national regulations in obtaining these Pest lists and pest categorization are
often updated.
two documents for all seeds or plant
materials sent or received. Similarly,
22

25. Dangerous pathogens on the move
The following pathogens provide the greatest threat to food security in sub-Saharan
Africa.
Cassava brown streak viruses
-Emerging virus disease of cassava
-Destroy tuberous roots
-Occurs in Kenya, Uganda, Tanzania, Malawi, and Mozambique
-Suspected in DRC, Congo, Burundi, Rwanda, Gabon, and Madagascar
Banana bunchy top disease
-BBTV-infected plants become unproductive
-Major constraint to fruit production and the production and distribution of quality
planting material
-Widespread in Central Africa
Banana bacterial wilt (BXW)
-BXW affects fruit production and quality, and kills the plant
-Widespread in East Africa
Present Present Present
Suspected No No
No information information
information
Cassava brown streak Banana bunchy top Banana bacterial wilt
when material is imported it is subjected has exchanged germplasm are Bénin,
to post-entry inspection to ensure its Ghana, Cameroon, Kenya, and South
compliance with the conditions specified Africa. Each of these countries has
in the import permit. Depending on the specific legislation. However, procedures
need, material is held in the post-entry for health monitoring have the same
isolation facility until the necessary underlying principle, i.e., the exclusion
clearances are obtained. Material that of pests and the prevention of pests
satisfies all the conditions is released for from spreading.
IITA’s use.
Phytosanitary protection of genetic
From 2005 to 2010, GHU, from IITA‘s resources
Ibadan Station in Nigeria in liaison GHU ensures the phytosanitary
with NAQS, has facilitated about 492 management of the germplasm of
exchanges, 157 imports, and 335 food crops (about 27,000 accessions)
exports of crop and other plant material conserved in the IITA genebank
to 69 countries, 34 of which are in and also in the in situ germplasm
Africa (Fig. 1). USA, India, Colombia, collections of breeding programs.
Mexico, and Japan are among the top Germplasm conserved in the genebank
5 non-African countries. Within Africa, is systematically evaluated for its
the top 5 countries with which IITA health status and clean germplasm
23

26. Fig. 1. Germplasm export and import events facilitated by GHU to various countries
around the world. Source: L. Kumar, IITA.
is conserved for distribution by IITA’s
Genetic Resources Center (GRC).
Contributing to phytosanitary capacity
development in SSA
Together with the Virology and
Molecular Diagnostic Unit and GRC at
IITA, Ibadan, GHU augments diagnostic
procedures for monitoring pests in
germplasm; develops a reference
pest collection and DNA bank to use
as controls; establishes DNA barcode
databases of the pests of African food
crops; and augments procedures for
salvaging clean germplasm.
GHU plays an active role in developing
the skills of NPPOs in the testing for
germplasm health and the production
of pest-free germplasm via training
courses and short-term assignments. It
also creates awareness on quarantine
pests, quality standards for planting
material, and the sanitary and
phytosanitary (SPS) measures.
Knowledge and technologies developed
are disseminated through training
programs, the publication of protocol
manuals, information flyers and
a website (http://www.iita.org/
germplasm-health). The unit also
collaborates with NPPOs and IAPSC
Information dissemination through exhibits as a technical partner to develop
and hands-on demos, IITA Open Day.
Photo by L. Kumar, IITA. phytosanitary capacity in Africa.
24

27. Dangers of unknowns
Certain basic knowledge on to occur in coastal zones of southern
pests is necessary to implement Africa for nearly a century. Like FSD,
phytosanitary measures. Examples aboveground symptoms of CBSD are
are the characteristics of the pest cryptic and difficult to recognize. Due
and its variants, its effect on the to insufficient knowledge on CBSD
host (symptoms), geographic and poor awareness, it is conceivable
distribution, alternative hosts, that cassava was moved, albeit
modes of spread, vectors, and inadvertently, from CBSD-affected
the availability of diagnostic tools. areas to other cassava-producing
Insufficient information compromises regions in Africa contributing to the
the phytosanitary inspection and virus spread in the continent.
demands very stringent measures on
the production of planting material. These two examples depict the
limitations of phytosanitary monitoring
For instance, frog skin disease and the potential risk for pest escape
(FSD), a virus-like disease of cassava if adequate precautions are not taken.
prevalent in certain parts of Latin To circumvent the limitations in
America, is difficult to diagnose diagnosis of uncharacterized, not-so-
due to insufficient knowledge on well-characterized, and cryptic pests,
its etiology and the lack of reliable monitoring programs are increasingly
diagnostic tools. Moreover, FSD relying on broad-spectrum diagnostic
does not induce characteristic tools, including deep sequencing,
symptoms in the aboveground parts which identify a range of related
of the plant further complicating species in the same genus, family, or
the detection of infected sources. order.
To avoid the risk of spreading FSD,
in vitro plantlets generated from Although these
cassava plants produced in FSD-free approaches reduce
fields are moved. However, only a the risk of potential
few organizations are capable of pest escape, they are
producing plants in this manner. expensive, laborious,
To obtain useful germplasm from and detect every
any agencies that are incapable of species including
producing planting material under benign endosymbionts
stringent phytosanitary conditions, and pose challenges
the material from the source requires to decisions on
that it be sent to a third party germplasm exchange.
capable of producing FSD-free plants. Another approach
This procedure severely delays the depends on the
exchange of material. production of “clean”
planting material
Similarly, the etiology of cassava using sources from
brown streak disease (CBSD) was pest-free areas.
unraveled in the late 1990s and GHU adopts both
succeeded by the development of these approaches to
diagnostic tests for cassava brown increase confidence in
streak viruses (CBSVs) that cause this germplasm health and
disease. But CBSD had been known safety.
25

28. Conservation of germfree-
germplasm
Dominique Dumet, d.dumet@cgiar.org and Lava Kumar,
l.kumar@cgiar.org
Plant genetic resources (germplasm) In the mid-1970s, IITA has initiated
are the foundation for sustainable an ex situ conservation of germplasm
agriculture and global food security. of important African food crops
They possess genes that offer resistance which are held in trust on behalf of
to pests and diseases and resilience humanity under the auspices of the
to abiotic stresses, such as drought United Nations. To date, IITA’s Genetic
tolerance, soil erosion, and other Resources Center (GRC) conserves
constraints. over 27,000 accessions of six main
collections of African staple crops,
However, genetic resources are eroding namely, cowpea and other Vigna,
at unprecedented rates as a result of soybean, maize, cassava, banana,
the loss of habitat, outbreaks of pests and yam. Germplasm is distributed
and diseases, and abiotic stresses. worldwide for use in research for food
Therefore, it has become imperative and agriculture. Depending on the
to conserve genetic resources for species’ reproductive biology and mode
agricultural sustainability and the of dissemination, collections are stored
preservation of global biodiversity. in field, seed, or in vitro genebanks.
However, germplasm (seeds or
vegetative propagules) infested with
pathogens such as, viruses, fungi,
bacteria, and nematodes, insects, mites
and even weeds (hereafter all referred
to as pests) can spread along with the
planting materials. Because of this
risk, planting materials are traditionally
sourced from healthy-looking plants
and as an additional safety measure
they are treated with chemicals to
eliminate bacteria, fungi, nematodes,
insects and other pests. However, viral
pathogens are difficult to detect and
pose challenges to “clean” (pest-free)
planting material production procedures.
IITA's collections were sourced over 35
years from several countries in Africa
and other parts of the world.
Knowledge on viruses infecting crops
conserved in the IITA genebank and
the means for their detection and
Seeds of important grain legumes are production of clean planting material
conserved in IITA's Genetic Resources have dramatically improved over the
Center. Photo by IITA. past two decades. To ensure that
26

29. planting material involves in vitro
procedures using meristem culture. In
cassava, source plants are subjected
to thermotherapy (exposing plants
to 27-30 °C) from 1 to 3 weeks prior
to meristem excision and in vitro
propagation. In vitro plants are indexed
for viruses and plants that test positive
are discarded while virus-negative
plants are further propagated for
conservation in the in vitro genebank.
So far, over 2000 accessions of clonal
crops have been subjected to this
process to derive virus-free plants.
Production and conservation of "clean"
planting material is expensive; however
it improves the turn-around time for
processing germplasm for exchange
and dramatically improves its use. In
addition, clean germplasm improves the
viability of the material conserved in
the genebank and prevents the risk of
Conservation of virus-free germplasm. the accidental spread of pests from one
region to another through the planting
germplasm conserved is free of pests, materials.
particularly viruses, a systematic
approach was taken to assess the
health status of every accession in the
genebank and produce clean planting
materials for conservation.
For seed-propagated crops (maize
and legumes), clean seed production
requires planting accessions in
contained screenhouses. Emerging
plants are monitored for symptoms and
each plant is tested using diagnostic
tools for all known seed-transmitted
viruses occurring in the territory where
they were last grown. Plants that test
positive for virus and/or showing virus-
like symptoms are destroyed. Seeds
are harvested from the virus-negative,
healthy-looking plants. Clean seeds
are then deposited in the germplasm
collections. This work started in 2008,
and so far over 4000 accessions of
legumes have been evaluated and clean
seed material produced have been
conserved in the genebank.
For clonally propagated crops (cassava,
yam and banana), production of clean
Researcher in genebank. Photo by IITA.
27

30. In Kanti Rawal’s footsteps:
wild cowpea from Nigeria
Remy S. Pasquet (rpasquet@icipe.org), Dominique Dumet
(d.dumet@cgiar.org), and Sunday E. Aladele (sundayaladele@yahoo.com)
Cowpea, Vigna unguiculata
(L.) Walp. is the major
legume crop in the African
lowlands. It is the main
protein supply of half of
the population in sub-
Saharan Africa.
Nigeria is the most
populous country in West
Africa, and also produces
the largest amount
of cowpea. Its urban
population is growing in
leaps and bounds, and
thus, it is also importing a
lot of cowpea from all its
neighbors.
Cowpea: dietary protein for millions in West Africa. Photo
Cowpea is considered by by IITA.
several authors as having
been domesticated in
Nigeria or within a larger Rawal traveled 38,000 Regarding Nigeria, Rawal
area including Nigeria (i.e., km around Nigeria and (1975) wrote in the
Vaillancourt and Weeden Niger. He collected wild abstract of his paper: “As
1992). In addition, the cowpea accessions as well in the case with many
first wild cowpea accession as numerous accessions of cultivated species, Vigna
was collected in northern domesticated cowpea. unguiculata (L.) Walp.
Nigeria by J.M. Dalziel, has a wild form growing
a British botanist, and According to his map
(see next page), he in secondary forests
this led Piper (1913) to
collected wild cowpea in and derived savannahs
propose the African origin
68 places (Rawal 1975). and a companion
of cowpea1.
Unfortunately, over the weed form adapted to
To some extent, this partly years, the passport data disturbed habitats such
explains why Nigeria was of these accessions were as roadside ditches
the first country surveyed lost and, today, the place and fields. Evidence of
for cowpea accessions of collection is known for introgressive hybridization
by IITA’s then Genetic only four out of the 40 between weedy and
Resources Unit. Between accessions still maintained cultivated forms has
1970 and 1973, Kanti at IITA. been presented. The
1
The African origin of cowpea was proposed 50 years earlier, when authors were split between those
supporting an African origin and those supporting an Indian origin. Piper, while successfully crossing
a domesticated cowpea and a wild plant from Nigeria, definitely proved the African origin of cowpea.
After 1913, the African origin of cowpea was not challenged anymore and definitely accepted.
28

31. N i g E R
Wild
Colonizer weed
Companion weed
Geographic distribution of the wild, the colonizer weed, and the companion weed forms
of V. unguiculata in Nigeria and Niger. The cowpeas are cultivated commercially in areas
between latitudes 8°N and 15°N (Rawal 1975).
zone of extensive natural first subspecies belongs to the diversity of cowpea
hybridization corresponds the secondary gene pool and wild Vigna in the
to the cultivation area of of cowpea and the second near future. To avoid the
northern Nigeria and Niger to the primary gene pool. irreversible loss of Vigna
and may well extend to However, since Rawal’s and to secure highly viable
Upper Volta (now Burkina material is mostly lost2, Vigna diversity, the Global
Faso) and Senegal.” the assessment of the Crop Diversity Trust in
diversity of wild cowpea association with IITA and
Rawal gave very good from Nigeria is impossible Nigeria's National Centre
descriptions of what he in the absence of new for Genetic Resources and
called the wild and weed collection missions in the Biotechnology (NACGRAB)
forms. His wild forms country. organized a collecting
were samples of subsp. mission for wild Vigna
baoulensis (A.Chev.) In addition, factors germplasm in 2010.
Pasquet; the weed forms such as climate change, The mission covered
were samples of subsp. increased incidence of 27,000 km in Nigeria
unguiculata var. spontanea pests and diseases, between 14 October and
(Schweinf.) Pasquet. We cultural change, or the 7 December and collected
(Pasquet and Padulosi in adoption of improved lines 260 accessions (242 of
press) believe that the are also likely to affect var. spontanea and 18 of
2
iiTA still holds 40 accessions, but this could be only one-third of the original number.
29

32. Fig. 1. Localities where subsp. baoulensis (red dots) and var. spontanea (green dots)
were observed.
subsp. baoulensis (Fig. 1). of Rawal’s survey and which is ”an uncultivated
In addition, 13 populations our own in terms of plant taxon that benefits
were sampled for further geographical distribution from human impacts
population genetic of both subspecies. or ’disturbance’," var.
analysis. spontanea is a weed
In the northern ranges, mainly encountered in
In comparison with the we often encountered
disturbed places, such as
Rawal missions that took wild cowpea in fields
in fields and gardens, at
place in 1971–73, we or at roadsides. Wild
roadsides, and sometimes
surveyed more localities cowpea plants are easy
within a shorter time. within towns (sewage
to spot in the field, as
Unlike Rawal, we focused ditches, grassy places); it
they twine 2–3 m above
on wild cowpea only and was not observed within
soil level on sorghum or
benefited from a much Yankari National Park.
pearl millet stems (Fig.
better road network, However, to some extent,
2). Domesticated cowpea
especially in northern var. spontanea is also a
are prostrate or short
Nigeria where we were and erect but usually not weed in the economic
driving more than 600 twining. sense of the word since it
km/day. In the end, there is usually pulled out from
is a general agreement Based on the ecological the fields by farmers. It
between the results definition of a weed, usually appears as isolated
30