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close this bookSPORE Bulletin of the CTA No. 38 (CTA Spore, 1992, 16 p.)
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Insecticides can increase pest damage

Groundnut farmers in India apply so much insecticide that they end up inducing pest outbreaks. Their counterparts in Africa rarely use chemical sprays, and their crops suffer less damage from pests.

Researchers at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India have been looking at why African groundnut crops suffer little from pest damage. It seems that because Indian farmers spray at least seven times in the season the natural enemies of the pests are just not able to recolonize the crops as quickly as the pest.

When the groundnut crop is quite young it is attacked by jassids and thrips. These cause only superficial damage, which results in no crop loss. But the farmers are encouraged to spray against the pest because the crop begins to look untidy and yellow. However, the spray not only kills the jassids and thrips but also the parasites of the groundnut leaf miner, the next major pest to appear.

Plant biotechnologies in Senegal

A new plan/biotechnology laboratory opened in Dakar, Senegal, in October 1991. It was funded by the French Ministry for Cooperation and was set up by the Senegal Institute for Agricultural Research (ISRA) and the institut francais de recherche scientifique pour le developpement en cooperation (ORSTOMl).

The complex consists of two large laboratories and four rooms for in vitro culture and planting seedlings, and accommodates 20 scientists. The laboratory is headed by Pape Sall of Senegal's DRPF/ISRA (Direction des recherches pour la production forestiere).

ORSTOM Route des Peres Maristes BP 1386, Dakar-Hann SENEGAL

When ICRISAT withheld sprays in their fields they found that 70-80% of the miners were parasitized and, in consequence they caused less crop damage. But if the parasites are killed, the miner can be very destructive. Later in the season the armyworm appears and starts to eat the leaves.

Farmers do not realize that these pests can eat up to half the leaves without having any affect on yield. Even when farmers do spray, the costs incurred are not recovered by the increased yield.

The last important pest of the season is Heliothis or pod borer. By this time any beneficial insects have been killed by all the previous spraying.

ICRISAT plant breeders have now bred groundnut lines that are resistant to jassids and thrips. ICRISAT hopes that farmers using these new lines will not use sprays early in the season. If sprays are withheld at that time there is usually no need to spray later on, because the beneficial insects have been able to increase their populations.

ICRISAT researchers hope that African farmers will be able to benefit from the results of these findings.

ICRISAT Patancheru PO Andhra Pradesh 502 324 INDIA

Book donation scheme for Africa

Many African libraries are unable to purchase books published outside their own countries because of lack of foreign exchange.

However, a new donation scheme jointly administered by the Ranfurly Library Service (See Source of Information page 16) and African Books Collective Ltd. will ensure in future that books from 20 African publishers will be made available to 12 major academic libraries in Africa.

With funds provided by donors the scheme will help to overcome severe book shortage in Africa and allow students and scholars in one part of Africa to gain access to the scope and vitality of African publishing from other parts of the continent. The administrators of the scheme hope that other funding will be forthcoming so as to extend the scheme to additional universities, and also to major public and national libraries in Africa.

Ranfurly Library Service
2 Coldharbour Place
39/41 Coldharbour Lane
London SE5 9NR, UK

Hot chickens need cool water

In hot weather chickens succumb to heat exhaustion, which very often leads to death. But an Israeli poultry farmer has found an easy solution to the problem: give the chickens cool water to drink.

A chicken has a normal body temperature of 39°C. It maintains this temperature partly by drinking water. However, the Israeli poultry farmer noticed that when the weather was hot the chickens actually drank less, and he suspected that the chickens were put off drinking because the water was too warm. Even using air-conditioning in the shed made no difference.

So he started to cool the water, and immediately the chickens resumed their normal drinking habits and fewer chickens died from heat exhaustion. The farmer has now developed a means by which water can be kept between 20°C and 25°C all the year round.

The system has now been tested by the Israeli Ministry of Agriculture. They found deaths from heat exhaustion dropped from 12% to 10%. There were other beneficial effects as well: egg production rose by 10%; the egg laying period was prolonged by a week and the number of broken eggs was halved because the shells were harder. It seems that the bird is able to absorb more calcium when it is drinking enough water.

Division of Poultry Science, Agricultural Research Organization The Volcani Centre, Bet Dagan, ISRAEL

Cypress aphid devastation

The Kenyan landscape is undergoing a dramatic change. The Mexican cypress tree Cupressus Iusitanica, which is grown on 45% of the country's total industrial forest plantation area, is falling victim to the cypress aphid, Cinara cupressi, an insect which causes dieback, discoloration and eventually death.

Infestations of Cinara cupressi have also been reported from Malawi, Tanzania, Burundi, Rwanda, Uganda, Zaire and Zimbabwe. The first reported sighting of the cypress aphid in Kenya was in March l990. Surveys only three months later showed that it had spread to over 80% of the country's forests and was also threatening windbreaks and hedges grown for fuelwood.

In the warm climate of Eastern and Southern Africa the cypress aphid does not overwinter for a prolonged period in an egg stage as it does in its indigenous northern temperate regions. Parthenogenetic reproduction continues year round and since the lifespan of a single generation is about 25 days, and there are no natural enemies, populations increase rapidly.

The aphids inject a salivary fluid into the tree so that they can digest the sap, but this is toxic to the tree. Feeding causes desiccation of the stems and the progressive dieback of heavily in(ested trees. Aphids also produce honeydew and this encourages the growth of sooty mould which can interfere with photosynthesis.

Long-term pest management options are being actively sought by FAO in response to a request from the government of Malawi and, in the UK, the International Institute of Biological Control (IIBC) has begun a search for a biological control agent.

In Kenya FAO has funded an emergency technical cooperation programme to help institute emergency control measures until a longer-term project gets under way.

A full-scale project will aim to establish an IPM system within five years. Eventually a combination of silvicultural, genetic and biological measures IS likely to be developed to counter the effect of the aphid but, in the short term, early harvesting of trees which are in danger of dying minimizes economic loss and reduces fire hazard.

Unasylva, FAO Via delle Terme di Caracalla 00100 Rome ITALY

Namibia doubles pearl millet yields

Most Namibians eat mahangu, a coarse cereal prepared from pearl millet. But despite its being a staple, no research was done on this crop in Namibia before Independence in 1990.

For most Namibians, the basic choice of food is between the flour of pearl millet and maize. Of the two, pearl millet is better adapted to semi-arid conditions. Maize does not grow well in the drylands of Namibia, which have low and unpredictable rainfall, consequently maize flour has to be imported. But farmers have now been introduced to a new variety of pearl millet, Okashana 1 (also known as ICTP 8203).

ICTP 8203 is an open-pollinated pearl millet variety developed at the International Crops Research Institute for the Semi Arid Tropics (ICRISAT) at Patancheru, India. The prominent characteristics of the variety are that it gives high grain yield, has a large seed, matures early, has resistance to downy mildew disease and yields well under end-of-season drought conditions.

With traditional cultivation practices, Namibian farmers have doubled their pearl millet yields. With improved cultivation practices they could even expect 2.4 tonnes/ha, about eight times the traditional yield of the crop. The consequence is that Namibia need no longer rely so heavily on maize imports.

Jugu Abraham
Information Services
ICRISAT Patancheru PO
Andhra Pradesh 502 324

Rapid on-farm multiplication of plantain and banana

Two new methods of propagating plantain and banana have been developed by the National Horticultural Research Institute in Nigeria. Both plantains and bananas are a major food in West Africa, but availability of propagating material has limited the expansion of groves 90% of which are owned by peasant farmers.

Lack of planting material and risk of disease transfer also pose problems for on-farm multiplication. The new methods use materials that would have been left to waste on the field and also ensure that true-to-type planting materials are used.

In the first technique, the split corm technique (SCT), corms are cut into sett sizes of 50g each and treated with fungicide. They are then air-dried for 24 hours before being planted in a 1:1 mix of forest topsoil and sterilized sawdust. New sprouts appear after four weeks from the date of planting and up to 20 plants have been obtained from one corm in this way.

The second method is the Split Bud Technique (SBT) and IS a modification of SCT. When the corn setts begin to sprout they are removed-from the nursery bed and split longitudinally into 4 sections. Using this method, up to 500 plants can be obtained from a single corm within 24 weeks.

These methods will greatly increase the supply of banana and plantain propagating material, especially as the methods are not complicated and require no specialized equipment.

B A Adelaja Fruits Division National Horticultural Research Institute PMB 5432 Ibadan NIGERIA

CGIAR annual conference

A significant budgetary cutback was adopted at the Consultative Group on International Agricultural Research's (CGIAR) annual conference in Washington held from 28 October -1 November 1991. 1992 will see the budget of $251 million cut by six million dollars.

Visvanathan Rajagopalan, Vice-President of the Bank for Sectorial Policy and Research, was nominated as next head of the consultative group by Lewis Preston, President of the World Bank; this appointment was confirmed by the conference.

The consultative group, now 20 years old, comprises representatives of 40 governments, the World Bank, FAO and UNDP. It has 16 centres for agricultural research, five of which are in Africa.

CGIAR, 1515 H Street, NW Washington DC 20433, USA

Inexpensive termite control

Termites can be controlled without resorting to costly imported chemicals. Field trials have shown that preparations using locally available materials have been effective.

In India, for example, Gondal fluid made from 100g gum, 200g asafoetida, 200g aloe and 80g castor cake, mixed well with boiling water and when necessary thickened with clay, was painted around the base of trees. Poison baits can be made from 25g Paris Green, 100g flour, 80g sugar, mixed to a stiff dough. Small lumps of - - the mixture can then be dropped into termite nests or into holes bored in the soil. Where there is a danger to People or livestock, an alternative using a mix of flour with 50g borax and 100g sugar can be used instead.

Mixtures of lime and sulphur forked into the ground discourage termite attack. Carbolic disinfectant powder, diluted tar or tar water, where they can be ape safely used, are also useful preventatives against termites.

For larger quantities of the mixes, the amounts in the formulae can be increased, providing that all ingredients are increased proportionately.

James Sholto Douglas Director, Hydroponic Advisory and Information Unit, 7 Melrose Road Galashiels, Scotland TD1 2AE, UK

Worm-free sheep

A tropical breed of white hair sheep, St Croix, shows a remarkable immunity to intestinal worms. Within four to six weeks the lambs have developed almost complete resistance.

Scientists at the Agricultural Research Service in Beltsville USA, have been comparing St Croix, which comes from the Virgin Islands with the Dorset. In trials St Croix lambs had 99% fewer worms in their fourth stomach than the Dorset lambs kept under the same conditions. They also passed only 0.5% as many worm eggs in the faeces.

Researchers have found that the resistance is connected with a large number of immune cells called globule leucocytes, which are found in the fourth stomach. It is thought that these cells prevent the worms from attacking the stomach lining. They might even cause the worms to be expelled from the stomach. Unfortunately when the St Croix are crossed with other breeds the cross-bred lambs do not inherit the resistance.

The researchers are now trying to understand how the immune process works. Hopefully this knowledge will make it possible to transfer the resistance to other breeds. Researchers hope that one day it may be possible to transfer this resistance to cattle.

Dr R Gamble Helminthic Diseases Laboratory USDA-ARS BARC East Beltsville MD 20705, USA

First hybrid pigeonpea released

Plant breeders at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India have bred the first hybrid pigeonpea. It is now being released to farmers. This is the first time any pulse crop has been hybridized.

The pigeonpea, known as ICPH8, is earlier than the present varieties. This means it escapes many diseases. Yields are 3040% higher and it is very adaptable, standing up to drought or high moisture very well. It has performed consistently well in trials carried out in many parts of India.

It has been difficult to breed hybrids because the flowers of pigeonpea, and other pulses, are self-pollinating. So the only way to achieve any genetic improvement was to find landraces that were male-sterile. Plant breeders searched through 5,000 accessions from ICRISAT's genebank. A few were found and these were used to produce a number of hybrids, of which ICPH-8 was the best.

Other hybrids are also being tested as they might be suitable for different regions. Some are being tested in Kenya for use in agroforestry systems. Work is also going on to produce hybrids of the vegetable pigeonpea for cultivation in India, Africa and the Caribbean.

ICRISAT Patancheru PO Andhra Pradesh 502 324 INDIA

Sweet potato development

Sweet potato breeders at the Asian Vegetable Research And Development Center (AVRDC) have developed several true seed populations of sweet potato. This has been achieved through polycrosses of clones from many geographical zones.

The polycross populations are basically broad genetic pools from which outstanding clones possessing desirable characteristics have been selected. These characteristics, such as high dry matter content, resistance to diseases like the sweet potato scab, good levels of betacarotene and adaptability to local growing conditions, have been the goals of AVRDC research.

Now, however, AVRDC has decided to phase out its sweet potato programme and pass on the work to the International Potato Center (CIP) in Peru. CIP already has many senior scientists working on sweet potato, which is their second principal crop.

AVRDC's germplasm collection is being duplicated and sent in vitro to CIP.

Courses and conferences


Wye College, 29 June-10/17 July 1992

A two-week briefing and training course for administrators working in agricultural and natural resource sectors. The course covers environmental economics, natural resource accounting EIA methods and procedures, economic appraisal of environmental impact of projects and policies. There is an optional third week on GIS/use of computers and environmental management.

Wye College, 13 July-18 September and 12 October-18 December 1992 A training course which provides thorough training in the use and application of standard packages including spreadsheets, databases, word-processing and statistics for rural development professionals: areas covered include survey data processing, project management, statistical analysis and software integration.

Details for both the above courses are available from: Mary Arnofd, Short Courses Office, Dept. of Agricultural Economics, Wye College Ashford, Kent TN25 5AH, UK

University of Southampton 28 September-16 October 1992

An intensive course organized in association with the Hydraulics Research, Wallingford, which draws on extensive experience of irrigation management methods and performance assessment techniques.

The Course Administrator, KIM Short Course, Institute of Irrigation Studies The University of Southampton S09 5NH, UK

19 July 1992 (3 weeks)

A course for librarians and information professionals in the use and management of agricultural and related information including: overview of prlmary and secondary literature sources; principles of indexing and abstracting, computerized information and storage retrieval, database management etc. Candidates should have written and spoken fluency in English, and professional qualifications.

The Senior Training Services Officer, CAB International, Wallingford Oxon OX10 8DE, UK

University of Sussex, 24 August-11 September 1992

A study seminar for professional library personnel involved in the management and development of library services which aims to give practical training on information systems for libraries based on micro CDS/ISIS with demonstrations of other systems for comparative purposes. Candidates should be proficient in English.

The Chairman, reaching Area, Institute of Development Studies at the University of Sussex, Falmer, Brighton BN1 9RE, UK

Silsoe College, June-August 1992

The course is designed for a wide range of land use professionals and its modular nature and case studies will allow for appropriate emphasis in certain topics to be selected by the participants. The primary aim is to increase the effectiveness of professionals in the diagnosis, analysis and design of mixed cropping systems involving woody perennials.

Student Recruitment Executive, Silsoe College, Silsoe
Bedford MK45 4DT, UK

MANAGEMENT OF RURAL PROJECTS AND THEIR EVALUATION University of Edinburgh, 28 September-4 December 1992 This course is designed for technical staff on development projects. The content includes: introduction to development, the role of projects and the project cycle; project identification and formulation; project appraisal prior to approval and funding and monitoring and evaluating projects.

Hamish Macandrew, UnivEd Technologies Ltd, 16 Buccleuch Place Edinburgh EH8 9LN, Scotland, UK

19-24 July 1992, Maastricht, The Netherlands

Those wishing to attend or to submit papers should write to: The Scientific Secretariat, WAP, England
6703 ET Wageningen, The

1-7 July, 1992 to be held at St; John's College, The University of Cambridge and The University of Warwick, Coventry, UK.

Miss Katherine Fort, Symposium Administrator, RASE, National Centre

Stoneleigh, Warwick CV8 2LZ, UK

Resurgence of interest in ostriches

Ostrich farming has been practiced in South Africa for over 120 years but the modern expertise in farming them comes from the USA. Now Zimbabwean farmers are increasing their interest, expertise and production, and exports are expected to exceed 15 million Zimbabwean dollars in 1992.

Exports of live wild ostrich are prohibited in order to conserve the small native population and therefore the gene pool, but farm hatched birds are likely to be exported to neighbouring SADCC countries. In America, intensive hatcheries are replacing natural incubation.

In the USA ostrich farming is a popular backyard industry. Currently, a cooperative is being set un to build and run a specialised abattoir in Zimbabwe. Once this has been built, ostrich farming may well become an enterprise for some of Zimbabwe's half a million small-scale farmers. With its very agreeable flavour, its high cluality protein and its low fat content the demand for ostrich meat IS reported to be well ahead of supply.

Kevin Grant, Ostrich Producers Association of Zimbabwe PO Box 1830, Harare, ZIMBABWE