Weedy Types Converge on Brazil

The III International Weed Science Congress (IWSC), held at Foz do Iguaçu, Brazil on 6-11 June 2000 was attended by 600-700 scientists. There were 53 scientific sessions and 16 specialist workshops. Of these, six were devoted to biocontrol and three to invasive weeds; in addition, one of the five all-Congress lectures had invasive weeds as the theme.

There were two sessions on classical biological control of weeds. One, chaired by L. Morin, reviewed the issues and provided an update on actual and potential classical biocontrol projects, particularly relating to pathogens, and how to create a framework for their implementation based on Australian experiences. The second session, chaired by J. Hoffmann, concentrated on `The impacts of classical biocontrol', especially the economic as well as the ecological benefits, with biocontrol of ragweed (Senecio jacobea) in the USA being used as an example (15:1 benefit cost ratio). Of all the projects analysed, 25% were regarded as successful with benefit cost ratios varying from 112:1 to 2:1. The negative impacts of classical biocontrol were also addressed.

There followed sessions on `Inundative biocontrol using fungal pathogens' (chaired by B. Auld), which involved an overview of bioherbicide research developments, with specific papers on Striga biocontrol, phytotoxins and formulation; and `Promising developments in bioherbicide research' (D. Sands), which covered novel formulations to enhance efficiency and also risk analysis relating to broad spectrum pathogens. A final session was devoted to `Synergy and the interaction of biocontrol agents with other methods' (C. Quimby), which concentrated on the integration of biological control and management systems using leafy spurge (Euphorbia esula) control in the USA as a model system. Earlier, a specialist session on `Modelling biocontrol effects' (M. Smith) had included presentations on the use of models for problem solving and assessing the impact of biocontrol, as well as in the dynamics of weed populations.

Weeders in Waders

A workshop on invasive species in aquatic ecosystems held during the Congress on 6 June, was attended by approximately 25 people from institutes, universities, governmental and non-governmental agencies from countries all over the world, including Brazil, Argentina, the USA, Italy, New Zealand, the UK and South Africa. The meeting was chaired by Dr. R. Charudattan from the University of Florida, USA, and two formal presentations were given. R. Pitelli (University of Sao Paulo, Jaboticabal) discussed the impact of native aquatic plant species, in particular submerged species, on hydroelectric power generation schemes in Brazil. H. Evans (CABI Bioscience) introduced a new project to identify pathogens from water hyacinth which are native to Africa for development into a mycoherbicide. He also presented data on a recent survey trip to the Upper Amazon River in Peru which, based on the diversity of insect natural enemies collected there, appears to be the centre of origin of the weed, from where the plant radiated throughout South America initially and then to the rest of the world. However, the diversity of pathogen species was poor in this area.

These papers were followed by an informal discussion on a range of topics, which included: the role of eutrophication in a aquatic weed problems; the role of changes in hydrology in aquatic weed problems; the success of biological control of water hyacinth on Lake Victoria; the need for new natural enemy species; sometimes weeds escape their natural enemies even in their region of origin and there might be a need to introduce natural enemies from another area; and the need for better integration of biological and other control options for aquatic plant species.

While water hyacinth formed the major topic of discussion at this workshop, other aquatic were also discussed, including Salvinia molesta, Myriophyllum aquaticum, several submerged aquatic plants and algae.

Pathological Weeders

The Congress was preceded by the V International Bioherbicide Group (IBG) Workshop on 5-6 June. Sixteen papers were presented during this 2-day workshop, which was attended by 35-40 scientists and organized by R. Barreto (Federal University of Viçosa). Encouraging advances in weed-pathogen targeting and product development were reported, ranging from new pathogens of rice weeds in the Philippines and Vietnam, to the potential commercialization of Fusarium tumidum as a bioherbicide against gorse and broom in New Zealand and Ralstonia solanacearum against tropical soda apple in Florida, USA, to the relaunch of BioMal (under the new name Mallet) against malvaceous weeds in North America. Canada, in particular, seems to be putting considerably more resources into bioherbicide research, especially as new weed problems arise and old ones are exacerbated by herbicide resistance and changing agricultural practices (e.g. zero tillage). A further stimulus is the government policy to ban all chemical herbicides from amenity areas, public rights-of-way and forestry. At the Agriculture and Agri-Food Canada Research Centre at Saskatoon, research is focusing on trying to exploit indigenous pathogens, even for alien weeds, but collaboration is also being sought in Europe for certain weed species against which no local pathogens have been found.

Several bioherbicide projects under development were discussed including those targeting Alternanthera philoxeroides, Amaranthus spp., Cyperus rotundus, Eichhornia crassipes (in USA and African countries), Matricaria perforata, Prosopis spp. and Striga hermonthica.

Of particular interest is the on-going research of A. Watson's group at McGill University, which is developing a `low-tech' product for use against Striga in Mali. Based on a strain of Fusarium oxysporum, chlamydospore powder formulations applied to the soil at sowing or to the seed completely inhibit weed emergence. The control strategy is geared to local needs and operates at a cottage industry level, utilizing a simple liquid fermentation process and cheap, easily available substrates such as sorghum straw. Women prepare the starter cultures in traditional cooking pots, using centrally produced primary inoculum (as gelatine capsules) to assure quality control, and then harvest, dry and store the powder. Prior to planting, the crop seeds are covered with an arabic gum-spore coating. This is being linked with a tree planting programme not only to provide arabic gum locally, but also to address the regional deforestation problem. This will give women in rural communities more socio-economic power. After further testing and refining, it is planned to transfer this technology to other countries in Africa affected by Striga weed.

J. Gressel (Israel) discussed some novel approaches to improve the efficacy and safety of bioherbicide agents by physiological and transgenic methods. M. Vurro (Italy) reviewed the prospects for using phytotoxins produced by fungi to improve the efficacy of bioherbicide agents through additive or synergistic effects.

The abstracts of the Congress have been published*. The next International Weed Science Congress will be held in Durban, South Africa in 2004. The next meeting of the International Bioherbicide Group will be held in 2003 in conjunction with either the International Symposium on Biological Control of Weeds in Canberra, Australia or the International Congress of Plant Pathology in Christchurch, New Zealand (to be decided).

*Anon. (2000) Abstracts of the III International Weed Science Congress, Foz do Iguaçu, Brazil, June 2000. Corvallis, OR, USA; International Weed Science Society, 301 pp. ISBN 1 891276 16 6.
Contact: International Weed Science Society, 107 Crop Science Building, Oregon State University, Corvallis,
OR 97331-3002, USA.

Challenges for Augmentative Biological Control

Understanding constraints to the adoption of augmentative biological control is a key issue in making it a success. The Indian Council of Agricultural Research (ICAR) and CAB International (CABI) Workshop on Augmentative Biocontrol, held in Bangalore from 29 June to 1 July 2000, addressed the problem by tackling a wide range of issues in depth. Discussions ranged from policy matters to details of research and production, to constraints in quality control and distribution and through to extension issues.

The workshop was funded by the Partnership Facility of CABI, organized by the Project Directorate of Biological Control (PDBC - Director, Dr S. P. Singh), jointly with CABI Bioscience, UK and was facilitated by Mans Lanting of Agriculture Man Ecology, (AME, Bangalore; AME is a bilateral programme between the governments of the Netherlands and India and works on sustainable livelihoods in the southern states). `Macrobials' and microbials (insect and pathogen biocontrol agents, respectively) were covered and the main purpose was to assess opportunities and constraints in the development of implementation. Thus a broad spectrum of stakeholders attended including government and university research staff, government extension staff, biocontrol specialists, commercial producers and NGO and government biocontrol laboratory representatives. The workshop consisted of day and a half of presentations and nearly the same on working groups for the production of recommendations.

An overview on the Indian scenario for augmentative biocontrol was given by S. P. Singh, and covered aspects relating to selection of superior strains, economical methods of mass production and application of bioagents, quality control, storage, shipment, safety issues, registration and identification of niche markets. Overviews of the global situation for augmentation, quality control and regulations were given for macrobials by S. Murphy, and for microbials by N. Jenkins, both of CABI Bioscience. Further presentations were grouped under sessions on: augmentation within the BIPM (Bio-Intensive Pest Management) system (with models from cotton, rice and vegetables), the role of extension, quality control, registration procedures, the role of NGOs, and commercial production.

In general, apart from the sugarcane industry, uptake of augmentative biocontrol in India is patchy. There is, however, good general support and in a few areas/crops, good demonstration (e.g. cotton in Andhra Pradesh and Gujarat; tobacco in Andhra Pradesh; and tomato and cabbage in Karnataka). The extent of uptake was found to be related to major factors such as extent of linkages (between research, extension and NGOs, for example), extent of government infrastructure, effectiveness of distribution, lack of biocontrol knowledge of farmers, and variability in the quality of products between commercial and also government producers. Attempts are now being made to address the last of these points: all the major microbials are now gazetted, and PDBC has begun to assess the quality of Trichogramma spp. used for the management of Helicoverpa in cotton. Despite these moves there is still need for methodology. Another major constraint identified was the availability of funding at the farm and village levels. Securing this for either purchase or production is frequently a problem. It was agreed that the relationships between, and importance of, all these issues is far from clear and needs further analysis.

A series of recommendations was drawn up by the working groups. These covered: policy matters; research and production (priority crops and research priorities); quality control (both general recommendations and specific ones for microbials and macrobials); industrial production (product quality, staff competence, extension and training, distribution and product availability, cost effectiveness of production, storage and shelf-life, packaging, simplification of registration regulations, the interface between research and commercialization, the government purchase system, tax exemption, health and safety in production, and patenting); and extension (production of biocontrol agents at different levels, distribution and promotional activities, hygiene, and impact assessment).

Although there is clearly much work still needed, this workshop was a landmark. Its real strength lay in the fact that it happened and that all sectors are beginning to speak with one voice. This was the first formal interaction between all the different parties involved in augmentative biocontrol in India, and the significance of this was acknowledged during the workshop.

Contact: Dr S. P. Singh, PDBC,
Post Bag No. 2491, H. A. Farm Post,
Bellary Road, Bangalore 560 024, India.
Email:
Fax: +91 80 3411961