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
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| Format: | News Item biblioteca |
| Language: | English |
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Technical Centre for Agricultural and Rural Cooperation
1992
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| Online Access: | https://hdl.handle.net/10568/45722 http://collections.infocollections.org/ukedu/en/d/Jcta38e/ |
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