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close this bookCERES No. 140 (FAO Ceres, 1993, 50 p.)
close this folderCerescope
View the documentAn old scourge reborn: Phylloxera attacks California grapes
View the documentMake way for super cassava
View the documentRat-killer extraordinaire
View the documentGenetic freshness: The biotech tomato heads for market
View the documentRabbit rearing is a frame of mind
View the documentIn brief:
View the documentFAO in action

An old scourge reborn: Phylloxera attacks California grapes

California's output of grapes is forecast to fall by over 100 000 tons by 1997, victim of the first outbreak in more than a century of the dreaded insect pest Phylloxera vastatrix. The infestation could cost the premium winemaking areas of the Napa and Sonoma valleys north of San Francisco more than US$1 billion in lost income.

Production isn't expected to recover until 2002. And with replanting estimated to cost between US$18 000 and US$24 000 an acre, many of the state's smaller wineries, already hard-hit by the long U.S. recession, are not expected to survive.

The Wine Institute of California (WIC) has been quick to dismiss reports of future shortages of local wine or higher unit prices as “scaremongering.” The institute's director, Andrew Montague, called the outbreak “a limited problem now under control. “ But the California wine consultancy firm of Motto, Kryla & Fisher (MKF) believes that up to 40 per cent of the valleys' production could be threatened.

The state's scientific establishment was apparently caught unawares by a vine disorder that seemed to have long since disappeared. The last great outbreak of phylloxera was in 1878 and on the other side of the Atlantic Ocean. Rootstock imported from the United States accidentally introduced the louse into European vineyards, causing what has been called “the greatest viticultural disaster since the Flood.”

Connoisseurs still debate whether wine tasted better before or after the pest decimated vines in France and Spain.

The vines wither

Phylloxera attacks the roots of the vine, sapping fertility, reducing fruiting and, ultimately, causing it to wither. The pest reproduces very rapidly, with up to five generations every 12 months. This means the number of phylloxera can go from zero to more than a billion in a single year if conditions are right. There is no effective treatment. Because phylloxera live under the soil, pesticides slow but do not stop their advance, and there are no natural predators. Eventually, the vineyards must be replanted with new vines, which then take three years to mature.

Phylloxera cannot tolerate sand or migrate across sandy areas, which is why small pockets of original viticulture in France's Champagne region and the Douro in Portugal survived a century ago. Chile, encircled by the Atacama Desert, is the only wine-producing country in the world with no history of phylloxera infestation. Elsewhere the solution, as in the 19th century, has been to graft local grape cuttings onto the American rootstocks considered most resistant. With very few exceptions, the entire European wine industry is now a product of that Victorian ingenuity one of the first examples of systematic hybridization.

The technique produces many different rootstocks with varying resistance and differing in the yield and quality of their grapes. One is AxR1, a cross between Aramon, a variety of Vitis vinifera, and Rupestris, a native American vine. Most European vineyard owners have abandoned it, finding it insufficiently resistant for local conditions, but in California, AxR1 became the mainstay of a fast-growing industry that saw wine-grape plantings increasing by 150 per cent in the 1970s. The Oenology Department of the University of California at Davis (UCD), an internationally recognized centre of viticulture studies, gave AxR1 its recommendation, and two-thirds of all vineyards in the Napa and Sonoma valleys as well as many other of the state's wine-producing areas are planted with AxR1 rootstock.

The present phylloxera outbreak was first identified in 1983. One thousand of the region's 70 000 acres have been grubbed out so far, and 43 000 more acres planted on AxR1 will probably have to be replaced over the next few years. Fast action is needed because of the furious pace at which phylloxera travels. In the Napa Valley a century ago, it took only seven years for the louse to wipe out 20 000 acres.

But how could a rootstock, widely recognized as resistant to phylloxera in the United States, suddenly succumb to such an epidemic? Viticulturalist James Wolpert, chairman of the Phylloxera Task Force at UCD, says the answer lies in a new biotype, a Phylloxera B, which has learned to overcome the resistance of the AxR1.

A mutant appears

“Phylloxera resistance is not a black and white situation,” Wolpert says. “It is a sliding scale. What we had was a rootstock that was resistant to phylloxera here, but its resistance was not absolute. Other countries had tried AxR1, especially back at the turn of the century. In these countries, the vine was not resistant. Under our conditions, we found it to be resistant. We had tests that went back 30 years, between the 1940s and '70s, and we had no problems. As it turns out, the bugs eventually caught up with us. They mutated. Exactly how, where and when that mutation occurred we don't know.”

The main evidence for a new biotype is the current infestation and, to many, its “discovery” could be little more than a damage limitation exercise by a scientific community caught with its trousers down. Says Robert Joseph, editor and publisher of Wine magazine: “Some people say biotype B is just A with another name. I believe there is a new strain but also that AxR1 is a time bomb.”

Wolpert admits that, after a century of inactivity, the phylloxera threat slipped down the list of priorities. “It's a difficult thing to study,” he says. “We need to know a lot more about how the bug and the vine interact. It's been a worldwide situation that about the time rootstocks come onto the scene, people stop studying the bug because it's not a problem anymore. Once you've got rootstocks, people say, 'I've got more pressing problems,' and move on.”

The epidemic is sure to transform the face of the California wine industry. Annual replanting rates are predicted to rise from an average of 1 000 acres in the two valleys to 10 000 acres in 1997, according to Vic Motto of MKF, while some 30 per cent of the total wine-grape area will be out of production. With the return of phylloxera, vintners with own-rooted vines in Lake County, Mendocino, the Foothills, northern San Joaquin and along the coast between Monterey and Santa Barbara will also have to replant.

Faced with three-year profit losses and steep replanting costs, many will certainly go to the wall. But for those who withstand the crisis, the outlook could be much brighter. With closer spacing-often double the number of vines per hectare-and newer trellis systems, growers can increase production from the 1980s' average of 3.5 tons per acre to six tons and get an estimated 700 bottles of wine for each ton.

The sixty-four dollar question is what rootstock to replant in the afflicted vineyards. UCD has recommended a number of alternatives- 5C, 3309, 110R and St. George. But they may not exist in sufficient quantity to supply the wineries' needs, and their suitability for specific soils and microclimates has not been fully established. “Unfortunately, little research has been done on the alternatives,” Motto says. “Replanting decisions are being made today based on insufficient information. New combinations of rootstocks, clones and growing conditions require new research to avoid or minimize problems. Trial plantings and more funding are needed.”

The next 10 to 15 years, Motto believes, will be a resting time for the industry, which stands to lose more than 50 per cent of its premium Chardonnay supply and 90 per cent of the premium Cabernet/Merlot. AxR1, the king of California wine, is undoubtedly dead, and the search for its successor goes on.

Michael Griffin

Make way for super cassava

A quiet revolution is taking place in the development of cassava, Africa's most widely grown staple food.

In the mid-1980s, the root crop was yielding an average of six tons per hectare on African farms. Then, the International Institute of Tropical Agriculture (IITA) in Nigeria developed the high-yielding variety TMS 30572. It was widely adopted, and on-farm yields doubled to 12 tons per ha. Now, cassava yields are set to double again, giving farmers four times more than they enjoyed less than a decade ago and offering important possibilities for improved food self-sufficiency.

Crop breeders at IITA in Ibadan have been working on the improved cassava varieties since the institute was set up in 1967. Part of the Consultative Group on International Agricultural Research (CGIAR), IITA's mandate is to increase the productivity of key African food crops and develop sustainable systems that replace slash-and-burn techniques.

Cassava, also known as manioc and yuca, grows in parts of Latin America and Asia as well as in Africa. The largest producers, along with Nigeria, are Brazil and Thailand. But it is of special importance to Africa where mostly small-scale farmers cultivate it under rain-fed conditions and some 200 million Africans in 30 countries-nearly half the continent's population-eat it daily.

What helps make cassava so important for Africa is that it grows in poor soils, does not require chemical fertilizer and can survive with little water. It needs only 60 millimetres of rain a month during the growing period, and if rainfall is less the plant's deep root system can tap underground soil moisture. In times of drought, when soil moisture is exhausted, cassava has a defensive mechanism-its leaves bear the lack of moisture. The leaves droop, but the tubers survive. Thus the claim that “where there is cassava, there is no hunger.”

About half of Africa's cassava is used for subsistence needs and half for commercial purposes. Because the tubers can be stored in the ground for more than a year, giving farmers the freedom to eat or sell when the need arises, it is a security crop. Tubers are processed into many different products, depending on local custom, including gari and fufu. In Latin America, the processing of cassava tubers into flour is thought to date back to 2000 BC.

New processing techniques

While it requires the least labor of all root crops, cassava processing by traditional methods needs a great deal of labor and is often done by families working together. But this too is changing. A post-harvest technology unit at IITA recently developed low-cost technology that substantially reduces processing time, saving about four hours a day of labor.

While cassava contains more calories per kilogram than any other root crop, it has the disadvantage of being low in protein. But nutritional value can be increased by fortifying the processed tubers with protein-rich crops like soybean. In areas where cassava is increasing, agricultural extension workers also stress the importance of growing vegetables.

To develop high-yielding varieties of cassava, IITA breeders crossed TMS 30572 with a wild species of the plant. This produced spontaneous polyploids, meaning the crossing of plant varieties had multiplied the number of chromosomes. The polyploids have up to four times the normal number of chromosomes and so offer the possibility of much higher yields.

The polyploids are undergoing extensive evaluations in four different agro-ecological zones in Nigeria-humid forest, moist savanna, semi-arid and mid-altitude areas. They are being grown and tested as far as possible under the conditions that exist on African farms, and several of the new varieties have reached the stage of testing on selected Nigerian farms. The results are highly encouraging. More than 200 triploids and tetraploids have been generated through open and controlled pollination, and two spontaneous somatic tetraploids have been adopted. Whereas TMS 30572 yields about 23 tons per ha on-station, some of the triploids are yielding 50 to 70 tons per ha.

Sang-Ki Hahn, a Korean crop breeder who heads IITA's cassava program, hopes the polyploids will yield up to 40 tons per ha, giving farmers two to three times more than present harvests. In the view of Lukas grader, IITA director-general, “The polyploids offer the potential for a significant breakthrough.”

A hedge against drought

The advent of this super cassava offers significant prospects not just for cassava-growing countries, but also for those where cassava is still little known. “In time of drought, cassava will survive when other crops wither,” says IITA crop breeder Alfred Dixon. Although it grows extensively across West and Central Africa, the crop only grows in small pockets in Southern Africa, which was hard-hit by drought in 1992. Maize, the staple food across most of Southern Africa, is vulnerable to drought, and scientists have been unable to develop maize varieties that can cope. “In Southern Africa, there is now a tremendous interest in increasing cassava production,” Brader says.

An Eastern and Southern Africa Root Crops Network, set up in 1987, helps countries of the regions develop root crops. IITA officials say that Zimbabwe is now trying to start a large-scale cassava program and that Zambia is expressing considerable interest in the crop. In Uganda, a World Bank project is helping expand the area under cassava.

Like maize, a small portion of cassava output is used for animal feed and for making beer, cosmetics and starches. “Cassava could be used instead of maize for such purposes, leaving more maize for food,” Dixon says.

IITA officials believe the new varieties will make cassava attractive to African farmers, both for their own food security and as a profitable commercial crop. The continent's growing population is raising demand and prices.

An IITA study of cassava in Africa found that in half of 275 villages in six countries that had not experienced famine, cassava was grown as the main crop. The study found that in villages where cassava was increasing, 30 per cent of growers said they were planting more of the crop as a hedge against hunger and famine, 25 per cent said it was because of growing population, and 20 per cent said it was because there was a good local market.

Cassava is planted out in stems, and in the next few years the all important link between research and higher farm yields will be the multiplying of stem material in order to bring super cassava to farmers' fields. Multiplication rates tend to be slow, and this could mean a delay in farmers reaping the benefits. But crop breeders are cautiously optimistic the new varieties will give Africa a long-overdue breakthrough to higher food output. “Africa will survive,” Hahn believes, “because of the advent of polyploidy in cassava.”

John Madeley

Rat-killer extraordinaire

Gliricidia septum, a fast-growing leguminous tree widespread in the tropics, has as many names as it does uses: “mother of cacao,” because its branches shade cacao plantations, “quick-stand” because it's easily propagated from cuttings, and “Imperata destroyer” for its herbicidal properties.

But the name that should mean most to small farmers is “rat-killer.”

Because rats attack plants at every growth stage, they pose a constant danger especially for high-density crops like rice. Some 10 per cent of the Philippine's entire rice crop is destroyed by rats every year, and recent advances in rat control have concentrated on such high-income cash crops.

But small farmers need help too. Unable to pay for high-cost pesticides, equipment and advanced techniques, they're forced to use traditional methods, which are rarely applied systematically and are often proved unsuitable. A better answer could be the use of natural toxins, which can be produced locally and require neither a high outlay nor external financing.

Enter Gliricidia septum, whose leaves contain a substance called coumarin which, under the effects of the bacteria produced in fermentation, is converted into the anticoagulant diacoumerol. Anticoagulants are an efficient natural method of pest control because they reduce the protein prothrombin, a clotting agent secreted in the liver, and eventually cause death from internal bleeding. Tests have shown that while the toxin that Gliricidia produces does not act rapidly, repeated doses lead to fatal hemorrhaging within a few days.

Unlike many other poisons, anticoagulants do not produce bait shyness, which rodents tend to acquire as soon as the first victims of other poisons are taken. And Gliricidia has a number of other advantages. It's not toxic to humans-in fact, its seedlings are even considered a delicacy. It serves as an excellent feed for livestock. It can form living hedges, posts for yam growing, provide green manure and enrich alley culture in barriers for erosion control.

Gliricidia septum acts potently on insects as well as rodents. In many countries, its leaves are placed in chicken runs, or left to soak in hot water and used to eliminate fleas and lice on domestic animals. In a survey in the Philippines, 72 per cent of the farmers interviewed said they put Gliricidia branches in their rice fields to keep bugs and other pests away.

U.S. scientists conducted research on the toxic effects of Gliricidia on rodents in Central America and reported in the American bulletin Echo Development Notes on how it is used. They found both bark and leaves effective.

Farmers in Honduras, they said, prepare the poison by taking two large pieces of bark from the Gliricidia tree and boiling them in water with about 10 kilograms of wheat. They toss the wheat into the fields, where rats and mice that feed on it die within days. Mexican farmers grind the bark or leaves, then mix it with damp wheat or spread it on banana slices. In Panama, they grind the leaves, mix them with cereals and leave the concoction to ferment in the hot humid weather, because this activates conversion of coumarin into diacoumerol.

Noting that no one has yet provided a precise formula for the poison, and that documentation is lacking on many farmers' experiments, Echo Development Notes has asked readers to send their individual recipes, including details on how they prepare the poison, what ingredients they use to make bait attractive, and whether their preparations can be stored and marketed. Ceres readers who can provide information should write: Martin L. Price, Echo-Development Notes, 17430 Durance Road, North Fort Myers, Florida 33917, U.S.A.

Fay Banoun

Genetic freshness: The biotech tomato heads for market

No longer need North American consumers put up all winter with pale pink tomatoes as hard and flavorless as golf balls. Soon other fruits and vegetables, from cantaloupes to cucumbers, will not only look but taste better, and frozen foods won't melt into mush when defrosted-all thanks to the advances of biotechnology.

In a move that left many critics uneasy, but the food processing industry satisfied, the U.S. government last year gave the green light to the new technology, rulina that food comprised of gene-altered plant material will not be regulated differently from foods made of conventionally bred plants. The first bioengineered food headed for market is the trademarked Flavr Savr tomato, guaranteed by its developers to taste vine-ripened and freshpicked.

Until the ruling by the Food and Drug Administration (FDA), the agency responsible for monitoring the safety of all drugs and many foods sold in the United States, the biotechnology industry had feared that foods produced by genetic engineering might be subjected to long delays for time-consuming tests and exhaustive regulatory procedures. The FDA decision set a precedent for the U.S. Department of Agriculture (USDA), which regulates the production and sale of conventional as well as genetically engineered meats, poultry and fish, and the Environmental Protection Agency (EPA), which oversees genetically engineered and conventional pesticides and genetically engineered disease and chemical resistance in plants.

There was an outcry from environmental and consumer watchdog organizations, but both government and industry were content with FDA's decision to give biotechnology the benefit of the doubt.

Almost simultaneously with the FDA announcement, the Monsanto Corporation reported what it called a “very significant” genetic engineering development that may lead to herbicide-resistant varieties of wheat. More than a dozen other American companies have already produced about 70 varieties of cucumbers, potatoes, cantaloupes and other plants that contain genes from other species which, the companies claim, improve their quality.

Ripe but not rotting

The Calgene Company of Davis, California, developed the Flavr Savr tomato by splicing an extra gene into the chromosomes of an ordinary tomato to delay the chemical changes that cause fruit to decompose rapidly after normal ripening.

Tom Churchwell, head of Calgene Fresh, Calgene's marketing subsidiary in Chicago, took issue with reports that the Flavr Savr's great virtue is longer shelf life. Its real advantage, he said, is that it does not need to be picked while still green, but can be left to ripen on the vine and still reach the market- and the dinner table-before it begins to rot. “Neither grocery managers nor anyone else wants to keep tomatoes sitting on a shelf for more than a few hours or a day or two. The real gain for consumers is that they can get tomatoes of homegrown quality at their grocery stores 365 days a year,” Churchwell said.

Calgene's tomato is patented, which is another aspect of the new technology that raises questions. Could anyone buy a Flavr Savr, scrape out some seeds and plant them in the back yard? “Yes,” said Churchwell, “but that would be a patent infringement.” Churchwell said Calgene is not worried that amateur gardeners will become serious patent infringers because they already grow garden-fresh tomatoes. What is at issue-and what is patented-is not a specific variety but a process that, Churchwell noted, can be applied to transform “almost any good variety.”

Calgene is contracting with farmers to grow the new tomato for sale in U.S. grocery stores but does not expect to market the tomato's seeds, Churchwell said. It plans to develop varieties adapted to a wide range of localities throughout the United States, and eventually other countries, and to contract with local growers to produce crops for their area's fresh produce markets.

Third World possibilities

“I think the possibilities for these products are particularly promising in less developed countries where distances are long and transportation from farms to market is slow,” Churchwell said.

Under the FDA policy that is making all of this possible, biotech products will be regulated like other foods. Like the producers of other foods, biotech manufacturers will operate on a kind of honor system in respect to food safety. It will be up to the manufacturers to detect or anticipate potential health hazards and call them to FDA's attention.

If a manufacturer uses abnormal biotech ingredients in a product- even when abnormal ingredients are of conventional origin-he is required to notify FDA and submit to testing for safety and efficacy before he can market the product. But if a product is comprised of material that is basically no different from what is in an ordinary product and the manufacturer has no reason to suspect it might pose a hazard to health, he can market it without specific approval from FDA.

The teeth in FDA's procedure come from its powers to seize and force off the market any product it finds to be unsafe. A producer who offers an unsafe or misrepresented food pays the penalty of losing credibility with his customers, forfeiting the costs of market development work and being left with an unsaleable product.

Although critics condemn this indirect regulatory power as inadequate, government authorities insist that what seems to be a permissive procedure is actually highly effective and provides U.S. consumers with a safe food supply. The alternative would be for FDA itself to carry out pre-market testing to ensure the safety of every new food variation as well as the enormous range of existing forms and brands. This would duplicate the effort and might almost match the multibillion dollar cost of the food industry's own tests and quality control measures.

Defending the government policy, officials assert that genetic engineering is essentially the same as conventional selective breeding and cross-breeding to establish improved characteristics. In announcing the policy, FDA said it is consistent with recommendations of expert panels on this subject convened by the National Academy of Sciences and the joint FAD/WHO consultation on food safety and biotechnology.”

Mixing flora with flounder

Critics, however, contend that no conventional breeder ever tried, much less succeeded in, such feats as scientists are now attempting-like introducing into vegetables a fish gene that keeps flounders from freezing while swimming in Arctic water. The aim is to stop frozen foods from getting mushy when thawed.

In a complaint filed with the FDA, Dr. Rebecca Goldburg, a senior scientist on the staff of the Environmental Defence Fund, proposed three new rules that would add an element of caution:

1) that the new policy require formal approval by FDA before gene-spliced foods can be marketed;

2) that labels be required to disclose all substances added by genetic engineering;

3) that FDA be notified of changes in the composition of genetically engineered whole foods before they are marketed.

The Foundation on Economic Trends, headed by Jeremy Rifkin, announced a “Pure Food Campaign.” He called for similar FDA policies, threatened lawsuits and boycotts of genetically engineered foods by merchants and consumers and launched a nationwide write-in campaign and television, radio and print advertising aimed at blocking the FDA policy.

But all these efforts are unlikely to change the new FDA policy immediately. FDA spokesman Brad Stone insisted that, like any other set of rules, the policy on biotechnology will stand until the passage of time shows it needs revision.

Robert G. Lewis

Rabbit rearing is a frame of mind

Consider the benefits of rabbit-keeping as a source of animal protein in the tropics:

- production can start with a relatively small investment;
- rabbits can survive and breed on forage-only diets;
- rabbit-keeping can be done by men, women or young children;
- rabbit meat is comparatively low in fat and cholesterol and high in protein;
- one carcass can provide a meal for a family;
- the meat is easy to prepare;
- there are few taboos against eating rabbit.

Logically, more rural people and villagers should be taking up rabbit rearing to feed their families and earn extra income. But that isn't happening. Instead, there is a growing list of disappointed rabbit-keepers and unsuccessful projects. The rabbit isn't at fault. It's the human factor that determines whether a rabbit production project will succeed or not.

When a project fails it is for one of six reasons:

1) Keepers treat rabbits as pets- The rabbit-keeper and family may become attached to their animals, seeing them as pets rather than sources of income or food. One way to avoid this and keep the objective clear is to choose a type of rabbit that is less pleasing to the eye. Different cultures find different animal colors more attractive than others. It is a good idea to identify these preferences and take them into account, selecting the most unattractive colors and types for production-perhaps rabbits of mixed colors instead of the handsome all black or white breeds.

It helps to ensure that the rabbits have an accepted single owner, rather than the traditional multiple ownership. New keepers should learn how to kill their rabbits in a quick, effective and humane way before they begin raising them, or one person should act as the specialist killer for a village or area.

2) Production levels haven't been decided on-When food is in short supply producers understandably try for maximum output, but this can be a serious mistake with rabbits. It is better to regulate production to reach optimum levels that are more likely to be sustainable.

Rabbits are prolific. They can produce litters of six to 10 offspring after a gestation period of only 30 to 31 days, which means one doe is capable of yielding 30 to 40 or more rabbits a year. This level of production is impossible in most of the rural tropics, where rabbit-keepers must depend almost totally on forage-only feeding for economic reasons.

If village rabbits produce litters of more than six and there is no concentrate food available for the doe, it is better to kill the weakest to reduce the litter size to three or four. Most rabbit-keepers find this difficult, if not impossible, but they have to learn to be realistic. If they don't cull the litter the chances are the large litter will be too demanding for the doe to feed. The litter will reach weaning age at six to eight weeks in a weakened state and will not be able to transfer successfully onto forages alone. Swollen stomachs and undernutrition will lead to coccidiosis or other complications.

Rabbits are biologically capable of conceiving when still suckling, but this is another bad idea. If keepers are patient and wait until after weaning before re-mating, the doe will have time to accumulate the fat her body needs to produce milk-a crucial source of high energy food-when the next litter is suckling. Regular weighing of the doe after weaning will show if she is putting on fat reserves. Delayed remating will mean lower annual production per doe but will increase the chances that the doe is able to produce.

3) The work involved may be underestimated-New keepers may underestimate the amount of work involved in rabbit production, starting with building the hutch. It may be impossible to protect rabbits from human thieves, but a hutch should keep out snakes, dogs and rats. Construction can't be done in a few hours from bits and pieces casually available. It takes time and considerable skill.

Once the rabbits are established, a keeper has to devote at least two hours a day to even the smallest rabbit unit. And there can be no days off to go to weddings or funerals, because rabbits need attention every day of the year.

To make up for the poor quality of most tropical forage, rabbits need a regime of “variety, little and often.» Keepers must spend from half an hour to two hours, three times a day, collecting grass, weeds and herbs and feeding them to the rabbits in small amounts. It's useless to put a big pile of food into the hutch for the entire day's feeding, because once the rabbits have trod or urinated on the food and it loses its freshness, they won't eat it.

It is worth remembering that, through their behavior, rabbits can tell the keeper a great deal about their needs and condition-but only if the keeper spends enough time observing them.

4) Keepers forget rabbits aren't people-New keepers often treat a new litter like human babies, thus doing more harm than good. To avoid painful mistakes, learn the essentials about rabbits before raising them.

Suckling habits are important. Human babies usually suckle their mothers six to eight times a day, but young rabbits are allowed to suckle only once or twice at most from the first day of life. The newborn litter needs to be left undisturbed so suckling can take place. Consequences can be serious if a keeper disturbs the litter and a feeding is missed.

It's also essential to know that, because rabbits must run fast to escape predators in the wild, they've evolved a very light skeleton, which is easily damaged. If a rabbit is handled roughly or dropped, its backbone can he injured and its hindquarters paralyzed.

5) Growers ignore consumer attitudes-Consider the preferences and attitudes of consumers before beginning production, because rabbit is not like other meats they are used to buying.

A shopper may be put off by a skinned rabbit carcass, thinking it looks like a cat or even a human baby. To get around this, it is a good idea to pre-cut portions, rather than present the whole stretched carcass for sale.

Consumers should also be warned that rabbit meat is so soft and tender it may disintegrate when boiled. Dry cooking methods are better.

6) The danger of escape is overlooked-When rabbit-keeping is under consideration, local officials and farmers are often concerned that some rabbits might escape, become wild and turn into pests of crops and vegetables. This has been a problem with undomesticated or semi-wild types, but not with fully domesticated breeds. Concern is warranted, however, because even when domesticated, uncontrolled rabbits can cause substantial problems. The possibility of escapers should be considered under specific local conditions.

Rabbit-keeping is not without problems, but the problems are surmountable. Given some study, a willingness to work hard and sensitivity to the consumer, the rearing of rabbits could become a growth industry for the tropics.

Denis Fielding

In brief:

· Researchers at the U.S. Department of Agriculture report a natural insecticide made from extracts of a tobacco plant mixed with water has proved 78 to 94 per cent effective against a major crop pest-the sweet potato whitefly. Biosoap, produced from the Australian tobacco plant Nicotiana grossed, destroys the fly by weakening its exterior protection. The insecticide is biodegradable and presents no danger to the environment. The pest, a tiny dipteron capable of reproducing every 17 days, attacks 600 species of plants throughout the world by sucking sap from leaves and fruit. It causes millions of dollars damage annually to fruit, vegetable, alfalfa and cotton crops in the western and southern United States alone.

· In an effort to achieve self-sufficiency in food within two years, the government of Bangladesh has called on farmers to produce three crops a year. Agriculture Minister Majid-Ul-Haq said his ministry will extend irrigation to 4.8 million hectares almost half the country's cultivatable land- and provide farmers with seeds and fertilizer. Bangladesh has produced about 20 million tons of food grain annually in recent years, leaving a gap of about two million tons to be imported to meet domestic needs.

· The International Livestock Centre for Africa has begun a project aimed at conserving Africa's indigenous livestock breeds and types, which are under threat from imported exotic breeds. The plan of action calls for an invento ry of African genetic resources and establishment of breed development strategies. Many centuries of adaptation to specific environments, diseases and plant systems have created great diversity in Africa's animal genetic resources. Now that improvements in veterinary care, nutrition and general husbandry have allowed crosses or replacement of native livestock with imported and improved exotic breeds to increase production, it is feared many indigenous breeds will disappear. The ILCA project is linked to a US$15 million FAO plan “to preserve the ancestral gene pool of domestic animals in the developing world.”

FAO in action


The important multipurpose tree Leucaeena leucocephala, better known as the ipil-ipil, is under attack by a fast-spreading pest that was little known only nine years ago. Since 1984, the Leucaena psyllid Heterosylla cubana has travelled, apparently carried on air currents, from Central and South America and the Caribbean to Hawaii, the Pacific Islands, Australia. Southeast Asia' the Indian subcontinent, Mauritius and Reunion in the West Indian Ocean and, in late 1992, to Kenya' Madagascar and Tanzania. FAO has warned African foresters that the pest a member of a group of insects known as jumping plant lice. now poses an immediate threat to all of Africa and asked them to report any infestations to forestry officials. The FAO Forestry Department advises that chemical insecticides should only be used as a short-term emergency measure. The search for long-term solutions centres on strains of giant Leucaena resistant to the pest. and on species of predaceous beetles and parasitic wasps that attack the lice.


Small farmers in China have achieved marked success in fattening beef cattle using a simple and well-known technology based on crop residues treated with urea-ammonia. The experiment is under way in 12 villages of Henan and Hebei provinces in a series of FAO and UN Development Programme projects (CPR/6768, CPR/8858 and CPRE/88/057) totalling US$696 000. The farmers fed young local Chinese Yellow beef cattle with treated straw and a supplement of cottonseed cake. Not only did they succeed in fattening 180-kilogram animals to 450 kg in just over 12 months, but they were able to keep cereals for human use or to feed other animals, and reduced the pollution caused by traditional straw burning. FAO experts report the same feeding technique could be used for dairy cattle, sheep, goats, breeding animals and other livestock.


With help from FAO's Plant Production and Protection Division, Cd'Ivoire is working to become self-sufficient in onions and reduce its trade deficit. The biggest problem was seeds. In order to grow the estimated 35 000 tons of onions consumed annually, farmers would need 11 750 kilograms of seeds, but production was only 1 500 kg. Popularizing onion-growing and developing a storage system were also considerations. Under the FAO project (IVC/88/008/B/01/12), three district leaders and 20 recruits were trained in seed production and shed-huilding. The national coordinator of the project made study trips to Guinea, Niger, the Netherlands, France and FAO headquarters in Rome. Now the information is going to the farmers, and as of December 1995, Cd'Ivoire hopes to have 300 farmers ready to produce onion seeds along with seeds for the local legume Gombo, sweet peppers and the Ndrowa eggplant.


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