9. A useful approach to the biocontrol of cassava pathogens.
In: Proc. of a Workshop for Integrated Pest Management of Root and Tuber Crops in the Tropics; IITA, Ibadan, Nigeria; Eds. Hahn and Caveness; 1987, pp. 86-94
This paper summarizes the research results obtained during the past 12 years on cassava pathogens, with emphasis on the use of fluorescent pseudomonads as biocontrol agents in different cassava production systems.
Investigations on biocontrol of crop diseases are increasing and are being seriously considered in many plant pathology programs around the world.
Research on the biocontrol of cassava pathogens was initiated at CIAT in 1975. Preliminary results are very encouraging, suggesting a useful, practical tool for controlling several pathological problems of cassava.
Darluca filum reduces disease severity and economic losses caused by Uromyces spp., a rust pathogen. Spray treatments with suspensions of Pseudomonas putida and P. fluorescens have reduced both number of angular leaf spots and leaf blights on susceptible cassava clones, and increased yields 2.7 times over untreated controls. Similar control treatments protected cassava cuttings against Diplodia manihotis and roots against postharvest root rot for 15 days in storage.
More investigation is needed into the practical storage of strains of fluorescent pseudomonads and into the distribution and multiplication of inoculum. Effective strains of these beneficial bacteria are available, and the methodology for their identification is known. Inoculating cuttings with bacteria is feasible in special situations, such as planting fields for material production, in order to control pathogens infesting the cuttings, and to protect against pathogens in infested soils. This technology may not be useful in traditional cassava production systems because the treatment requires technical work and aseptic handling during the production of the inoculum. Further research is also needed on the use of beneficial bacterial suspensions to treat cassava roots before storage in order to identify effective strains and develop treatment systems, giving levels of control similar to those obtained with thiabedazole. A likely development in the near future will be the use of growth-stimulating strains of fluorescent pseudomonads to treat both cuttings or plantlets before planting, for the promotion of root system growth.
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Africa, Egypt, study, faba bean, Orobanche, trap crop, flax
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