Chromolaena Workshop Proceedings

The proceedings have been published of the 5th International Workshop on Biological Control and management of Chromolaena odorata*. The workshop was held in Durban, South Africa in October 2000 under the auspices of IOBC (International Organization for Biological and Integrated Control of Noxious Animals and Plants).

As is usual and useful in the outputs of such workshops, country and regional reports (from Congo-Brazzaville, Ghana, Indonesia, Malaysia, Micronesia, Papua New Guinea, the Philippines and South Africa) form a major part of the proceedings. These review the distribution, mechanisms of dispersal, spread and impact of chromolaena, together with status of efforts at containment and/or management in the various countries. The importance of raising awareness of (a) the threat from the weed and (b) the need for resources to combat it are highlighted in presentations from South Africa. A Malaysia report describes how chromolaena is causing coconut plantations to be abandoned. Classical biocontrol is a popular (but not universal) choice, with herbicides, manual control and burning also used. The need for rehabilitation of infested land is discussed in a South African paper, and countries where it is perceived as a useful resource note the need to replace chromolaena with alternative species. Countries are at various stages in control programmes, and reports of successful establishment, spread and impact of natural enemies (for example Cecidochares connexa in Indonesia) make encouraging reading, and in particular the successful control achieved with Pareuchaetes pseudoinsulata in Ghana. Progress with assessing new prospective agents is summarized in another South African contribution (and there is more on biocontrol in later papers). A different perspective is given by Australian contributions, where chromolaena is not yet established, and they focus on prevention, early detection and hopes of eradication.

Papers on the taxonomy of the tribe Eupatorieae and chromolaena from morphological and DNA-based studies and contributions on the effects of environmental factors on seedling growth, species invasion and regeneration potential - together with one on the impact of the weed on crocodiles - provide useful baseline information for future integrated management strategies.

Contributions that consider impacts and management of chromolaena in both natural and agricultural systems strategies indicate how the impact of the weed may be lessened. From discussions of, variously, lessons learnt from control efforts, how fire may be used to regenerate chromolaena-free land, the Farmer Field School approach in training farmers in biocontrol, and how best to substitute for chromolaena in a cropping system, "judicious guidance" emerges as the key term.

A series of papers on current biological control projects for chromolaena, in conjunction with the country reports, provides a useful accumulation of knowledge on which agents have been released where, and how they are performing. There are also contributions, for various natural enemy species, on host specificity testing, mass rearing, biology, and impact on flowering and foliage, and land management practices, following release. Significant issues include the potential for pathogens, and why Pareuchaetes spp. moths have failed to establish in some instances.

A report on the 6th International Workshop on Biological Control and Management of Chromolaena is in the `Conference Reports' section of this issue.

*Zachariades, C.; Muniappan, R.; Strathie, L.W. ( eds ) (2002) Proceedings of the 5th International Workshop on Biological Control and Management of Chromolaena odorata , Durban, South Africa, October 2000. Pretoria, South Africa; ARC-Plant Protection Research Institute, 186 pp.

Available from: ARC-PPRI, Publications,
Private Bag X134, Pretoria,
0001 South Africa
Email: nipblk@plant1.agric.za
Fax: +27 12 808 1489
Web: www.arc.agric.za

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