Experts concerned with Africa's banana sector are
trying to increase production of the crop that currently feeds about 100
million people in sub-Saharan Africa. But their efforts are threatened by
diseases that result in banana farmers across the continent losing half their
yields – and sometimes even more. Scientists warn that this could soon lead to more
severe food shortages in some parts of Africa. For many on the continent, the
green boiling banana is a staple food, and they depend on it to save them from
Bananas are particularly susceptible to
disease, says Dr. Irie Vroh, a molecular geneticist with the International
Institute of Tropical Agriculture. He explains that this is because bananas
grow directly from "mother plants," and not from seeds.
the roots of the mother plant grow many small progenies…. They are clones of
the mother. So, if the mother is sensitive to a disease, the progenies are also
automatically sensitive to that disease," Vroh tells VOA from his office in
Ibadan, Nigeria, where he leads his organization's West African banana program.
"Disease is one of the main problems affecting banana and plantain…. Diseases
and pests are a major problem for these clonally propagated crops."
Dubois, a Belgian scientist with the Consultative Group on International
Agricultural Research, adds that when farmers take cuttings from banana plants
they're unaware are infected with disease, and replant them, or sell or
exchange them with fellow growers, they unwittingly spread plant sicknesses. In
so doing, he says, their crops are often "wiped out."
In Kampala, Uganda, Dr. Fen Beed studies diseases afflicting African
"I try to determine how exactly the disease spreads and how it infects
plants, and try to identify interventions based on this," he says.
Beed explains that bananas in Africa, and especially in East Africa, are
currently succumbing to a disease that was first diagnosed in Ethiopia in 2001.
Wilt attacks African bananas
Bacterial wilt – scientific
name, Xanthomonas – causes banana
plants to literally waste away. The leaves of infected plants turn yellow, and
ooze yellowish fluid. Bunches of bananas ripen prematurely and rot. Beed says
the disease has destroyed up to seventy percent of crops in afflicted areas. As
a result, some countries aren't producing enough cooking bananas to feed their
"(Bacterial wilt) has spread
right across Uganda, and more recently has spread into Rwanda, Tanzania, Kenya,
Congo and is suspected in Burundi," says Beed.
He says the disease has
"devastated" banana production in Uganda, which harvests 10 million tons a
year, making it the world's second largest banana producer after India.
Analysis of the situation in the East African nation reveals that the disease,
if uncontrolled, will result in the loss of almost 60 percent of production in
the near future.
The scientific website,
Science Development Net, has quoted a Ugandan government official saying
bacterial wilt could cost his country up to eight billion dollars in the next five to ten
years, with the majority of the population likely to be in danger of hunger.
say no matter what measures are taken by Africa's agricultural sectors against
bacterial wilt, the disease is extremely difficult to prevent and control. Beed
says the sickness affects banana plants at such a "rapid" rate that by the time
farmers become aware that there's something wrong with their crops, it's too
late to respond effectively.
insects are also carriers of the disease, and most African farmers can't
feasibly spray their banana crops with chemicals to protect them against
infection by pests. Dubois says because of the "immense" size of banana plants,
the crops would require a lot of chemicals, and this proves too expensive for
the vast majority of African farmers – even in places where such pesticides are
available for sale.
say plants infected with bacterial wilt can't be cured; the best farmers can do
is to take preventive measures to control the disease.
advise farmers to uproot infected crops," Beed states, but then continues, "one
of the things that was most disappointing was that once we did recommend the
removal of infected plants, there wasn't a system in place within the national
frameworks of the countries in which we're operating to actually replace this
infected material with new, clean material."
Beed says African banana
farmers are trying to get clean plants in an effort to resume production. But
in most cases, they're too poor to do this.
that system wasn't in place to try and combat the losses that they'd suffered.
That's actually resulted in some farmers moving away from banana to growing
cassava and maize; this is true of central Uganda."
acknowledges, though, that impoverished African farmers are hesitant to destroy
their only means of livelihood. Yet even when they've taken this radical step,
the negative consequences have mounted.
perennial qualities of the banana enable the soil to be maintained. This
prevents erosion and environmental degradation, retains the structure and the
water within the soil. So when bananas are removed as a consequence of disease,
it's not just damaging to the banana industry, it's damaging to the
environment…. It causes erosion," Beed explains.
are constantly advising that farmers not use implements that they've used on
infected plants on other plants, and to sterilize their tools. But Beed says
information about preventive measures such as this often doesn't reach farmers,
most who live in very isolated areas.
He posits that the wilt "catastrophe" offers evidence that "no system is
ever that durable because the pathogens can always adapt, or new pathogens can
be introduced. This is particularly apparent when we see that both trade and
commerce of agricultural products is increasing all the time, so there's always
this risk of a disease coming in (to a country)."
Other diseases set to hit Africa
warns as well that Panama disease, one of the "most notorious" of all plant
diseases, is set to strike in Africa in the near future. This sickness has
wiped out production in South America of the previously popular "Gros Michel"
Beed says Panama
disease is particularly hard to control, as it's constantly mutating and is set
to threaten production of the Cavendish dessert banana in Africa.
we're facing now is that there's another race of Panama disease, which is
called tropical race four, which is present in Asia and will come to Africa at
some point, and this will knock out Cavendish, because the Cavendish doesn't
have any resistance to this particular form of the disease," Beed tells VOA.
Dr. Irie Vroh adds that black sigatoka, a leaf spot disease caused by fungus, is also having a "devastating impact" on banana production in sub-Saharan Africa.
Beed also warns as well
of the intensification in Africa of banana bunchy top virus that causes the
stunting of banana plants.
"It seems to be
attacking all types of banana. This is particularly worrying because we're not
quite sure why it has started to spread," Beed says.
Scientists say no
banana variety is resistant to this virus, with infected plants largely unable
to bear fruit.
surveys and investigating and analyzing its molecular constitution, to try to
determine why it is now becoming more of a problem than it ever was before,"
says Beed. "We're trying to determine what the main parameters are encouraging
the spread of this… such as climate, location and so on. If we can do that,
then we'll better be able to identify control interventions."
Tissue culture solution
says a potential long-term answer to the disease danger facing Africa can be
found in the laboratories of international agricultural research organizations.
farmers nowadays can do – and what is being done all over the world except in
Africa – is something called tissue culture. This is a technique by which you
produce small little plants in a laboratory, in a sterile condition (and in so
doing) you make clean planting material," he explains. "You get rid of the
pests and diseases that normally associate with banana plants before you plant
them in the field. This is also a very quick way to very rapidly multiply lots
and lots of bananas."
says bananas also grow much faster through the use of tissue culture.
gives farmers the chance to get more income, to market the products they get as
a result of those tissue cultures," he enthuses.
though, acknowledges that plants raised from tissue cultures are a "bit
fragile" and require further scientific modification to enable them to survive
under harsh African conditions.
put them in fields that are burdened by pests and diseases and that are
suffering from bad management in Africa, these plants need something extra. So
I put microbes in those plants, to bolster them and make them into a kind of
super-plants, to stimulate their immune system," he says.
Dubois and other scientists agree that such technological advancements are
presently beyond the reach of the majority of African banana producers, who in
the near future are set to continue to suffer the wrath of diseases.