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Although we can never be completely certain, analysis
of both nuclear and mitochondrial DNA fingerprints and of Phytophthora
infestans allozyme argues strongly that the disease lived undisturbed,
in the shadow of the Toluca Volcano, for perhaps thousands of years. As
a fungus, it propagated clonally and gradually mutated in the cool, humid,
forests that dominated the valleys of Mexico's central highlands. Sometime,
possibly early in the 19th century, the relatively benign fungus expanded
from its forest hosts to other species, especially the potato. What havoc
it may have wrought among the Otomi, Huastec, and other agriculturalists
is not recorded. The Huastec however, practised (as they do to this day)
a highly-sophisticated form of forest management known as te'lom which
allowed them to utilise as many as 300 different forest species including
81 species directly for food. Such a diversified production strategy would
have kept P. infestans in check , at least up until the time the
Spanish introduced crop monoculture.
From the forest to the field
Researcher William Fry at Cornell University theorises
that an American biologist may have accidentally brought P. infestans
home with him from an expedition to the volcano in the early 1840s, not
long before American soldiers occupied the region during the Mexican-American
War. What is known is that sometime in the autumn of 1843, the outbreak
of a devastating new disease was reported in Philadelphia. Somewhere in
the city's outskirts an epidemic was boiling, and no antidote was available.
Yet, whether it was a change in the weather -- which had grown unseasonably
cool and rainy -- or some other factor, the potato blight did not advance
further. Worries subsided until the following year -- again in the autumn
-- when the disease seems to have hopped to the maritime provinces of
Canada and the American mid-west. It killed wherever it landed. The disease
appeared to have been airborne - capable of moving as much as three or
four miles a day. Wherever it landed, destruction occurred within 24 hours.
But, once again, as quickly as it came, the disease faded into the background.
Although it never truly disappeared and, indeed, returned from time to
time to repeat its destruction, it never reaped the ruin in North America
that it was about to visit upon Europe.
In June of 1845, Phytophthora infestans struck
again. Belgian newspapers reported the first signs of the disease, and
the country braced itself for disaster. Throughout the summer, P.
infestans surfaced in the Netherlands and then Germany. Not long
thereafter, it was on the fringes of Moscow, ravaging Spain out to the
Canary Islands, and searing the Balkans.
On August 17, 1845, newspapers announced the arrival
of the death fungus in Ireland. On October 15th, the British Prime Minister
declared Ireland a disaster area. The disease swept from one shore to
the other almost overnight and, for almost four years, held sway over
the lives of millions. Before it faded -- but, as in America, never vanished
-- more than a million (perhaps as many as 1.5 million) Irish were dead,
and a quarter of the population had fled.
There were sporadic rumours of the fungus's continuing
devastation. Stories from Spain and the Balkans, tales of destruction
as far away as China, and in parts of Africa then hardly known to Europeans.
Modern DNA probes now show these rumours to have been true. The disease
even doubled back from Europe into Brazil where its impact was the same
as everywhere else. By the 1860s, however, the rumours petered out and
the world gradually forgot. All that was left were the unmarked mass graves
and the continuing devastation to the psyche of the nations and the families
who survived.
The second epidemic
The fungus remained a muted force among the poor for
more than a century but it never again reached the heights of destruction
felt in the 1840s. But then, in the mid-1970s, the disease broke free
of the volcano's shadow once again. Epidemiologists know for a certainty
that a more aggressive strain (dubbed genotype A2) of P. infestans
was found in Switzerland in 1981 and that scientific evidence traces the
pathogen back to the central highlands of Mexico. In the same year, 1981,
the "new" P. infestans struck The Netherlands and Germany.
The UK was hit in 1984, and the disease materialized in Poland in 1988
and Ireland in 1989. According to Dutch and American investigators pursuing
the fungus, European traders -- likely Belgian and Dutch -- inadvertently
carried the disease with them to Egypt in '84, Japan in '85, and then
to points as diverse as Rwanda, Israel, and Brazil in the late 1980s.
By the beginning of the 1990s, Korea, The Philippines, Taiwan, and Bolivia
all reported outbreaks of the new A2 strain. In every encounter, the disease
mysteriously presented itself only to fade, reappear, and fade again,
causing limited but recurring destruction. Some claimed it was the cool,
humid weather that brought it on. Others simply counted their blessings.
By 1992, epidemiologists noticed that P. infestans
had changed. Evidence suggests that the two strains of the disease, types
A1 and A2, converged sometime that year in a field in British Colombia
on Canada's Pacific coast. Not only were there two distinct types of the
same disease together, they were mutating rapidly and multiplying differently.
Where the fungus had previously evolved, ponderously, through clonal reproduction,
the convergence in Canada's far west meant the disease could now propagate,
much more aggressively, sexually.
In 1994, like a tropical depression, the "new"
sexually-reproducing P. infestans gained hurricane force and leapt
through the United States and Canada. The scientific sleuths tracking
it counted numerous different forms of the fungus --each more vicious
than the last --and the last forms were resistant to every available chemical
remedy.
In that same year the new strains appear to have bridged
the Atlantic and begun another march through Europe. It is also spreading
from cargo shipments to Rwanda and other parts of central Africa, and
back to Latin America via Bolivia and Ecuador. In the closing quarter
of 1995, investigators know they were dealing with one of the most dangerous
plant diseases the world has ever seen. The economic interests at stake
are huge. Just the hint of a new potato famine has doubled potato prices
in some parts of the United Kingdom. Last year, farmers in New York State,
hit by the blight, had $100 million in crop losses added to another $100
million in extraordinary expenses trying to contain the disease. With
more virulent forms of the disease cropping up in the US state of Idaho,
farmers are braced for an assault on their $587 million potato harvest,
and the government is alarmed that their $2.6 billion potato-processing
industry is in jeopardy. This pales in comparison to the world-wide implications
of a new pandemic: in 1992 the farmgate value of the global potato market
was $40 billion and the world potato industry -- including processing
-- was valued at $160 billion.
Food Security
The real threat, however, lies neither in western Europe
nor in North America. From a crop originally domesticated in the Andes
and, later, cultivated in Central America, the potato has risen to become
-- after rice and wheat -- one of the world's most critical sources of
carbohydrates and a farm product for 129 countries. Since the 1970s, international
agricultural research programmes have evangelised the undoubted merits
of the bountiful tuber throughout Africa and Asia. According to one study
the nutritional value of the potato ranks second only to eggs and is well-ahead
of wheat or beans. A strong case was made that the potato produces more
food -- of higher dietary value -- per hectare than any other crop.
Yet, in retrospect, the evangelism seems a little overblown.
Even as the A2 strain began its latest march across Europe, the International
Potato Centre (CIP) in Lima, Peru, released an epistle from one of its
economists arguing that policy-makers in the South "grossly underestimates"
the economic and nutritional merits of the potato. Decrying the fact that
farmers in the South "account for only 15%" of the world's cultivated
potatoes, CIP identified the barriers to increasing potato production
as unfounded historic biases and high production costs (commercial tuber
seed in the late seventies could cost as much as US$1,000 per hectare).
There was not a word about P. infestans and the ongoing ravages
of even the original A1 strain.
Belgian and Dutch seed potato companies were quick to
follow public research programmes selling their own varieties throughout
the Third World. Seed companies created markets in the Middle East, and
East Asia. The trade also looped back from the Benelux countries to the
crop's centre of genetic diversity in the Andes. The fungus tagged along.
Outbreaks of the more aggressive disease genotype have been identified
in Bolivia, Ecuador, Colombia, and Brazil. Seed company interest in the
Third World market grew as the potato acreage in the North declined. Between
1961 and 1991, land sown to the crop in industrialized countries was almost
halved. During the same period, acreage doubled in Asia, and almost tripled
in Africa, making the South the growth market for commercial varieties.
As it was 150 years ago, potatoes continue to be the
crop of the poor. Some of the world's poorest countries have been encouraged
to plant potatoes as a new staple. Researchers now speculate that the
original strain of P. infestans spread accidentally from Belgian
missionaries into east and central Africa (Zaire, Rwanda, Burundi, Uganda)
many decades ago. Today, about 110,000 hectares of this highland area
--on both sides of the Zaire-Nile Divide --are seeded, by small farmers
with half-hectare plots, to the new crop. Three-quarters of their harvest
goes for home consumption.In this region, potatoes can mean the difference
between survival and starvation.
Back in Europe, the people likely to suffer most from
a new blight, are the Poles, Russians, Ukrainians and (east) Germans who
eat as much as two or three times the quantity of potatoes consumed in
Western Europe. Russia is the world's number one potato producer. A crop
failure in eastern Europe or the republics of former USSR could have disastrous
human consequences.
Despite the alarm for the African highlands and eastern
Europe, perhaps the greatest danger lies back in the Andes. If the sexually-mutating
strains of P. infestans, reach the shores of Lake Titicaca --where
potatoes have been grown for almost 6,000 years --then the genetic diversity
of the crop could be wiped out. The entire world depends upon the unique
Aymara and Quechua-bred cultivars (and their associated species) sown
throughout the region. There is a real risk that the fungus could eat
away the genetic resources we will need to defeat it.
If potato breeders were unduly complacent about late
potato blight in the sixties and seventies, they were properly alarmed
by the mid-eighties. By 1992, CIP estimated that the disease was cutting
Third World yields by 30% and that fungicide control campaigns, related
to late potato blight, were costing the Third World $600 million each
year. Global fungicide costs are estimated to be $1.8 billion -- making
potatoes the most chemically--intensive food crop in the world. In a frantic
effort to outbreed the fast-mutating fungus, CIP released more than 250
new potato clones to 27 countries around the world. Among the hardest
hit locations are Rubengeri in Rwanda and Rio Negro in Colombia. Scientists
recognize, however, that nothing offers farmers or consumers true security.
Blight Blunders
At least in part, the present threat is the product of
over-enthusiastic potato evangelism, backstopped by aggressive company
marketing, foolish breeding strategies, and reliance on a single commercial
fungicide. The only widely-used fungicide effective against the disease
was, Metalaxyl, developed by Ciba-Geigy, the giant Swiss Pharmaceutical
house. It had proven effective against the original strain, but Metalaxyl
was impotent in the face of later forms of the Type A1 fungus as well
as Type A2 strains. Some international researchers maintain that Metalaxyl,
sold under the trade names Rindomil, Apron, Subdue and Acylon, accidentally
but inevitably, created the more aggressive disease by forcing the fungus
to mutate around the chemical for its own survival. The worry now is that
fear of the new strains will push governments to accept still more potent
chemicals contributing to a cycle of toxics and disease that will only
threaten humanity further.
There are also grounds for questioning the breeding strategies
of both public and private institutions. Some years ago, in order to fend
off the A1 fungus strain, breeders opted for a strategy of single-gene
vertical disease resistance, creating a series of short-lived fungus resistant
potato varieties. Breeders put up one resistance gene after another until
a succession of 16 different resistance-genes had been thrown into commercial
potatoes --each outgunned by a fungus that only grew meaner and leaner
with each fight. The first resistance gene stayed in the ring 6 years
but by the time breeders released the sixth resistance gene the crop could
barely survive a season. Breeders now agree that single-gene resistance
was a bad idea. The only real beneficiary was Ciba-Geigy -- still selling
metalaxyl to ever more desperate farmers.
The political disease
But then, the problem was, and still is, only in part
caused by P. infestans. When the British were criticised in the
1840s for not buying enough food to feed the starving Irish, the government's
famine coordinator replied, "Our purchases, as I have more than
once informed you, have been carried out to the utmost limit short of
seriously raising the price in the London market" The London
rulers were clearly more concerned about market prices at home than about
the inhabitants of the other island far away. Historians could well argue
that the havoc wrecked in the 1840s was not caused so much by P. infestans
as by private investment and the marketplace. Historians concur that there
was never a food shortage in Ireland. For every shipload of (usually indigestible)
food aid that reached Irish docks, six or more shiploads of cereal crops
left the same ports for markets in England and Europe. The hungry had
no control over this haemorrhaging of food stocks abroad. The land tenure
system, taxation, and the mercantile theories of the time were what killed
people
Remarkable little seems to have changed over time. On
the 16th of October 1995, Agriculture Ministers from 165 nations convened
at the Chateau Frontenac in Quebec City to mark FAO's fiftieth anniversary
with a special conference on world food security. One of the tasks of
this conference was to look at a draft declaration that will be signed
by Heads of State at the Food Summit next year. To date, the draft being
considered reads more like a stockholders' report than a campaign to vanquish
starvation. The word "farmer" arises only once in the brief
document. "Investment" or "investor", on the other
hand, appears 22 times -- more often than FAO refers to "government".
Exchange or interest rates and discussion of GATT's Uruguay Round are
more common than the word "hunger". There are more references
to the economic or investment "environment" than to the ecological
"environment". On the only occasion in the draft Declaration
where the word "sanctity" arises, it is in the context of the
"sanctity of contracts". The solution to world hunger, it would
seem, lies in private investment and the marketplace. This is the language
of the IMF, the World Bank and the World Trade Organisation -- not of
a United Nations agency dedicated to a war against hunger.
We seem to be turning full circle. One hundred and fifty
years ago, a fungus slipped out of the Toluca Valley through the USA and
Canada to decimate Ireland and terrorise Europe. Today, more virulent
forms of the same fungus have again escaped the eroded forests of Toluca
to sweep across North America into Europe and, propelled by international
trade, to the Third World. In 1845, the solution to hunger was a free
market. In 1995, the answer is said to be the same. Farmers are left to
place their faith in the weather and hope for the best.
This article was taken from RAFI
Occasional Paper Series, Vol .2, No 6, August 1995. It was
edited by GRAIN to fit into a Seedling article format. The original text
was prepared by RAFI staffers Pat Mooney, Hope Shand, and Edward Hammond
with assistance from Beverly Cross and Jean Christie. The full paper is
available from RAFI, 110 Osborne St., Suite 202; WINNIPEG, MB R3L 1Y5;
CANADA; Phone: (1-204) 453 52 59, Fax: (1-204) 925 80 34, E-mail: rafi@rafi.org.
Cost: $US 10, free for Third World NGOs
Selected sources:
* Cecil Woodham-Smith, The Great Hunger, Harper
and Row Publishers, New York and Evanston, 1962.
* CIP, "Economic Impact of High-Yielding Late
Blight Resistant Varieties in the East and Central African Highlands",
in CIP, Case Studies of the Economic Impact of CIP-related Technologies,
(First Draft), January, 1995.
* Fry, William E. et. al., "Historical and Recent
Migrations of Phytophthora Infestans: Chronology, Pathways, and Implications",
Plant Diseases, July, 1993, p.653.
* Alcorn, J.B. "Development policy, forests,
and peasant farms: Reflections on Haustec-managed forest contribution
to commercial and resource conservation" Economic Botany, 38(4),
1984, 389-406.
* "Potato blight mystery: DNA traces fungus to
Mexican tomato", Biotechnology Newswatch, July 3, 1995
* Fry, William E. et. al., "Historical and Recent
Migrations of Phytophthora Infestans: Chronology, Pathways, and Implications",
Plant Diseases, July, 1993, .
* Goodwin, Stephen B. and William E. Fry, "The
Genetic Composition of Phytophthora infestans Population in the United
States During 1994: A Preliminary Report", (unpublished manuscript),
December 19, 1994,
* Sahm, Phil, "Blight Threatens Idaho Economy",
The Idaho Statesman, July 25, 1995, p.1B.
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