Cratylia: A hardy forage
shrub for dry areas
A drought-tolerant shrub that CIAT has been
experimenting with for many years as a forage crop is proving
highly attractive to small beef and dairy farmers in Colombia’s
vast savannas and piedmont area. During 2002 the Colombian
Corporation for Agricultural Research (CORPOICA) released
a superior CIAT genotype of Cratylia argentea, a protein-rich
legume native to Latin America, under the varietal name Veranera.
“The farmers we’ve been working with are using
Cratylia not just in the dry season but all year round,”
says animal nutritionist Carlos Lascano, manager of CIAT’s
Multipurpose Tropical Grasses and Legumes Project, which is
supported by the Japanese and Colombian governments, among
other donors.
In tropical America dual-purpose (milk and beef) farms account
for 78 percent of the overall cattle industry and 41 percent
of milk production. Most of these are small operations that
depend heavily on pastures for animal feeding. In many livestock-raising
areas, particularly Colombia’s savanna and Central America’s
hillsides, there is a long, forage-scarce dry season. In the
savanna, where it lasts 2 to 3 months, cattle producers are
hard pressed during this period to keep up milk production
and even maintain their animals’ health. They have to
buy expensive commercial feed supplements, which drives down
their already low profit margin.
But a recent ex ante study on the economic potential of Cratylia,
conducted by CIAT livestock economist Federico Holmann, provides
good reason for optimism. The analysis covered several production
scenarios. It showed that use of this shrub, which grows even
under conditions of low soil fertility and acidity, can significantly
lower farmers’ production costs for beef and milk. For
example, if 2,500 shrubs are planted for each hectare of grass
pasture and replaced every
5 years, costs go down by 19 percent.
“Making these enterprises more efficient and profitable
helps the rural poor by creating more jobs,” says Lascano.
“But if you want to have widespread impact, private sector
links are vital.”
During 2002, CIAT continued its Cratylia evaluations with
14 farmers in Colombia’s piedmont—the transitional
area between the savanna and the Andes, which serves as the
breadbasket of the capital Bogotá and other cities.
This participatory research is supported by Colombia’s
World Bank-funded National Program for the Transfer of Agricultural
Technology (PRONATTA).
The farmers tested several technologies for growing and using
the legume. These include protein banks from which leaves
are regularly cut and carried to corralled animals; establishment
of shrubs in grass pastures for direct grazing by animals;
and preparation of silage from fodder not consumed in the
dry season. Farmers are also producing seed for sale to their
neighbors.
The farmers’ experiences have been highly positive,
says Lascano. They report being able to milk their cows during
the dry season, and replacing expensive supplements with Cratylia
has no adverse effect on milk production. With local demand
for seed of the shrub on the rise, CIAT has contracted eight
agricultural schools to grow Veranera seed.
A safe biopesticide now on the market
A baculovirus shown by CIAT to be highly effective against
cassava hornworm, a major agricultural pest, is now available
as a formulated commercial pest control product in Colombia.
The biopesticide was developed under an R&D partnership
between the Center and BIOTROPICAL, a biopesticide company.
The new product, which kills the hornworm larvae during their
early development, is easy to apply, relatively inexpensive,
and ecologically sustainable.
BIOTROPICAL has received a manufacturing formulation licence
for the baculovirus from Colombia’s Ministry of Agriculture
and Rural Development. It now produces, markets, and distributes
the biopesticide under the name “Bio Virus” and
has been contracted by partners in Mexico to supply the product
there as well.
The cassava hornworm (Erinnyis ello) is a migratory insect
whose outbreaks in cassava fields are unpredictable. Under
high infestation losses of the cassava root harvest generally
range between 20 and 65 percent but are sometimes higher under
repeated hornworm attacks. If the outbreak occurs early in
the crop cycle—between the 2nd and 5th months—it
takes only 5 larvae per plant to defoliate the crop. Later
in the cycle, as plants mature, it takes about 30 per plant
for total defoliation.
“The best strategy against the hornworm is to synchronize
your response with the start of the insect attack,” says
entomologist Anthony Bellotti, manager of CIAT’s Integrated
Pest and Disease Management Project. “We needed a product
that could be used exactly when the outbreak occurs.”
The arrival of Bio Virus on the market will provide major
benefits to farmers. In Colombia cassava production is on
the rise, especially for the commercial starch and animal
feed markets. Between 1996 and 1999, for example, cultivated
area grew nearly 15 percent.
As part of its pest management work, CIAT has taken part
in training events aimed at familiarizing Colombian cassava
farmers with the handling and application of the baculovirus.
In a recent workshop in the southwestern area of Tolima, farmers
applied the product to a cassava crop severely infested with
hornworms. At a dosage of 300 grams of the formulated baculovirus
per hectare, the farmers observed a larval mortality rate
of about 91 percent.
CIAT’s work with BIOTROPICAL on hornworm control is
just one step in a broader program: development of a research-based
model for industrial production of biological pesticides to
control the pests of cassava and other crops. The latest focus
of research is another major pest, the cassava burrower bug
(Cyrtomenus bergi), which also attacks crops such as onion,
peanut, and coriander. A fungus called Metarhizium anisopliae
has proven highly effective against the burrower bug. One
CIAT isolate of the entomopathogen killed 70 percent of the
target insects within 19 days.
The first-ever whitefly-resistant food
crop variety
Fifteen years of collaborative cassava research by CIAT and
the Colombian Corporation for Agricultural Research (CORPOICA)
have finally paid off—and very handsomely. In May 2003
CORPOICA released Nataima-31, a variety that resists a highly
destructive species of whitefly called Aleurotrachelus socialis.
Whiteflies are among cassava’s most important insect
enemies, and A. socialis is the predominant species in northern
South America.
Nataima-31, a cross between Ecuadorian and Brazilian cultivars
from CIAT’s germplasm bank, is the first whitefly-resistant
cassava variety to be officially released anywhere. And it
is apparently the first of any food crop to possess elevated
whitefly resistance. The new variety also has other big advantages.
It gives a high yield, resists thrips and mites, and is suitable
for both human consumption and industrial processing into
starch and other products.
The resistance is so good that farmers are being advised
not to apply any pesticide. With some local varieties grown
in Latin America, producers need to apply antiwhitefly chemical
pesticides 6 to 10 times during the year-long growing cycle.
Besides posing hazards to human health and the environment,
this strategy tends to backfire. Whiteflies have a very short
life cycle, just 30 to 35 days. Genetic adaptation, and therefore
the emergence of pesticide-resistant whiteflies, are rapid.
Another whitefly species, Bemisia tabaci, is currently extending
its geographic range. It transmits viral diseases to many
plant species, especially horticultural crops, and also feeds
directly on their leaves. However, in Latin America it rarely
colonizes cassava—at least not yet. In Africa, B. tabaci
transmits cassava mosaic disease (CMD), including a virulent
form that has devastated crops on the eastern side of the
continent. Researchers are concerned that if CMD jumps to
Latin America, it could—with the help of a new biotype
of B. tabaci that has been observed on cassava—eventually
reek havoc. The problem is that the most widely grown types
of cassava in the neotropics have no resistance to the disease.
This potential new threat, plus the need to transfer whitefly
resistance to African cassava, has led CIAT to collaborate
with the Natural Resources Institute (NRI) in the UK. The
joint research aims to determine which cassava genotypes resistant
to A. socialis whitefly might also resist B. tabaci. Results
to date are encouraging.
CIAT’s work on whitefly resistance, funded by the New
Zealand Agency for International Development (NZAID), is just
one element of a concerted global research effort called the
Tropical Whitefly Integrated Pest Management Project, which
is currently funded by several donors, including the UK’s
Department for International Development (DFID). Other topics
of CIAT investigation linked to this project are management
practices to combat whiteflies, the nature of resistance mechanisms,
and biological control methods, such as the use of predator
insects, parasitoid wasps, and entomopathogens.
An encouraging line of attack in the area of biocontrol has
been the identification of a whitefly entomopathogen called
Verticillium lecanii. With observed insect mortality rates
of about 65 percent, this fungus is a good candidate for commercial
development.
Exploring the environmental effects
of GM crops
With funding from Germany’s Federal Ministry of Cooperation
and Economic Development (BMZ), CIAT recently launched a research
project to improve understanding of how genes flow between
cultivated crops and their wild or weedy relatives. Latin
American rice and beans are the crop models for current field
and molecular studies in Colombia and Costa Rica.
Gene flow has caught international public attention mainly
because of concerns over the environmental safety of genetically
modified (GM) crops. Genetic transformation of plants through
biotechnology raises important questions: under what circumstances
are “transgenes” likely to make their way into the
DNA of other plant species, and will this have different effects
from the gene flow of nontransgenic crops. A frequently cited
fear is that a transgenically induced trait, such as resistance
to a herbicide, pest, or disease, could be transferred to
close relatives of the GM crop through a natural process called
outcrossing, turning them into “super weeds.”
Gene flow, along with random mutation, is a basic mechanism
of plant evolution, an engine of biological diversity. Through
hybridization genes from one wild plant population sometimes
mix with those of another. Likewise, DNA may flow between
conventionally bred crops and their wild relatives.
“Many of the questions being asked these days about
the environmental and human safety of GMOs apply equally to
conventionally bred plants. Gene flow has always been there.
It’s part of normal crop evolution. What we want to do
in this new research is step back and take a look at the issue
from a broad perspective,” says rice geneticist Zaida
Lentini, who led the CIAT team that produced the first transgenic
rice resistant to rice hoja blanca virus, a major threat to
Latin American rice production.
In recent work Lentini and her colleagues studied various
physical and behavioral characteristics of red rice—a
highly variable “weed complex” that often displays
traits of cultivated rice, wild species, or both. They collected
red rice plants and seeds from fields in the Tolima region
of southwestern Colombia, where farmers were growing popular
commercial (but non-GM) varieties of rice (Oryza sativa).
These samples were sorted according to the variety being grown
in the field where they were collected.
The idea was to identify highly variable, easily recognized
traits in red rice, since these can serve as practical tell-tale
signs of gene flow from cultivated rice. Husk and grain color,
the presence or absence of awns (tiny bristles on the flowering
part of the plant), growth and flowering patterns were among
the most variable traits observed. This so-called morphological
and phenological analysis demonstrated clear similarities
between a number of the red rice biotypes and their companion
cultivated varieties. And in other cases there were strong
trait associations with wild rice, particularly O. rufipogon.
A complementary element of the research is the use of molecular
markers (microsatellites in this case) to pinpoint genetic
similarities between cultivated rice, red rice, and wild species.
From a pool of 50 candidate microsatellites, the researchers
recently identified 14 that will be useful in tracking gene
flow.
CIAT expects that these gene flow studies will add to the
knowledge base needed by national biosafety authorities to
decide wisely about the deployment and management of transgenic
crops in specific circumstances and locations.
Rural youth inherit the planet
CIAT is capitalizing on the fact that today’s children
are tomorrow’s stewards of the earth. It is doing so
through two recently launched youth projects, one in Honduras
funded by the Canadian International Development Agency (CIDA)
and the other in Colombia, funded by the USA’s W.K. Kellogg
Foundation. The pilot projects are adapting participatory
research approaches to the needs and abilities of young people.
Participants range from preschoolers to university students.
In collaboration with local schools and NGOs, CIAT trains
selected youth in participatory research methods, experiment
design, and group facilitation. The youth facilitators in
turn lead groups of children in experiments on natural resource
management and food production. This approach aims to give
fledgling youth research groups the continuity and leadership
needed for their evolution into effective, permanent organizations.
In Honduras groups have been formed in six communities, involving
a total of 143 youth. Research topics include methods for
combating river pollution, evaluation of tree species for
firewood, and the establishment of vegetable gardens. CIAT
and Canada’s University of British Columbia jointly organized
a 3-day workshop to introduce the pollution research group
to watershed management concepts and methods. With the help
of computer-based presentations, the young researchers learned
about water resource mapping and the use of vegetative buffer
zones to protect streams.
In southwestern Colombia CIAT has joined forces with three
groups: an association representing 38 schools, an NGO specializing
in research on sustainable agriculture, and a youth group
dedicated to environmental conservation. The work is centered
in the Garrapatas River watershed, an area covering 250 square
kilometers on the western flank of the Andes Mountains.
Ten youth research groups have been formed under the umbrella
of the Association of Educational Centers in the Garrapatas
River Watershed (ACERG). Led by senior students at the region’s
only high school, youth researchers (both primary and secondary
school students) selected their research topics themselves
and are now experimenting with such options as biointensive
vegetable gardens, bamboo production, and small-scale production
of poultry, fish, and cattle.
“The school association has been keen to have agriculture
play a greater role in our curriculum,” says school director
Adriana Abadía. The students’ experiments are
thus a good fit with one of the three broad themes promoted
by ACERG: agroecological education. The other two are rural
enterprise development and ethnoeducation (the study of local
Andean history, culture, and language). Together, explains
Abadía, these themes reflect the policy of the watershed’s
two municipalities to create viable rural livelihoods and
make their mountain landscape a more attractive home for their
children—economically, socially, and environmentally.
Marta Rodríguez, 18, is one of the students supervising
the bean research. She has even replicated the experiment
in her own community, 31 kilometers from the school. “If
our experiments succeed, we’ll get the results to other
farmers,” she says.
CIAT and ACERG have two local partners in the youth research
project: the Center for Research on Sustainable Agricultural
Production Systems (CIPAV) and an environmental youth group,
Inheritors of the Planet, Bellavista, or HPB. CIPAV helps
rural communities conduct nature-conservation research linked
to improved farming practices. Its positive experiences have
rubbed off on local youth. With funding and technical assistance
from CIPAV, several children of one of the original collaborating
farmers launched HPB in 1995. They began doing their own environmental
research, conducted inventories of tropical fauna and flora,
and eventually set up a 3-hectare biodiversity reserve for
study. The group, which now has 36 members, is collaborating
with ACERG in mentoring younger children in research techniques.
|
