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close this bookAbstracts on Sustainable Agriculture (GTZ; 1992; 423 pages)
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View the documentAcknowledgements
View the document1. Designing integrated pest management for sustainable and productive futures.
View the document2. Biotechnology's bitter harvest: herbicide-tolerant crops and the threat to sustainable agriculture.
View the document3. Chemistry, agriculture and the environment.
View the document4. Mise au point de techniques appropriées de lir qui seront utilisés par les petits agriculteurs traditionnels d'Afrique tropicale.(developing appropriate ipm technology for the traditional small-scale farmer in tropical Africa).
View the document5. Biological control in developing countries: towards its wider application in sustainable pest management.
View the document6. Transforming plants as a means of crop protection against insects.
View the document7. Utilization of va-mycorrhiza as a factor in integrated plant protection.
View the document8. Activity of four plant leaf extracts against three fungal pathogens of rice.
View the document9. A useful approach to the biocontrol of cassava pathogens.
View the document10. Evaluation of the biological activity of flax as a trap crop against orobanche parasitism of vicia faba.
View the document11. Insect pest management.
View the document12. Economic contributions of pest management to agricultural development.
View the document13. The effects of intercropping and mixed varieties of predators and parasitoids of cassava whiteflies (hemiptera: aleyrodidae) in Colombia.
View the document14. Prospects for traditional and cultural practices in integrated pest management of some root crop diseases in rivers state, Nigeria.
View the document15. Studies on cowpea farming practices in nigeria, with emphasis on insect pest control.
View the document16. Effect of various fertilizers and rates on insect pest/pearl millet relationship in Senegal.
View the document17. Insect pests of intercrops and their potential to infest oil palm in an oil-palm-based agroforestry system in India.
View the document18. Using weather data to forecast insect pest outbreaks.
View the document19. Insect pest management and socio-economic circumstances of small-scale farmers for food crop production in western Kenya: a case study.
View the document20. Rodent communities associated with three traditional agroecosystems in the San Luis potosi plateau, Mexico.
View the document21. Grain storage losses in Zimbabwe.
View the document22. Controlling weeds without chemicals.
View the document23. Weed management in agroecosystems: ecological approaches.
View the document24. Manual on the prevention of post-harvest grain losses.
View the document25. Evaluation of efficient weed management systems in pigeonpea (cajanus cajan l.)
View the document26. Weed management in a low-input cropping system in the Peruvian Amazon region.
View the document27. Poblaciones, biomasa y banco de semillas de arvenses en cultivos de maiz zea mays l. Y frijol phaseolus vulgaris l. Efecto de m+todos de control y rotaciones. (Weed population, biomass, and seed bank in maize and bean crops. Effects of control methods and crop rotations).
View the document28. Effects of groundnut, cowpea and melon on weed control and yields of intercropped cassava and maize.
View the document29. Intercropping and weeding: effects on some natural enemies of African bollworm, heliothis armigera (hbn.) (lep., Noctuidae), in bean fields.
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7. Utilization of va-mycorrhiza as a factor in integrated plant protection.

Agriculture, Ecosystems and Environment, 29, 1989, pp. 131-135

The natural growth area of rubber trees is the tropical rainforest of Brazil in which very poor soils are present. In preliminary studies it was shown that rubber trees form a VA-mycorrhiza under natural growth conditions. The influence of VAM on plant pathogen interactions has been studied for a number of plants but rarely on woody plant species and therefore no conclusive data for trees like Hevea brasiliensis are available. Young Hevea trees reveal a rhythmical growth pattern, in which leaf flushing occurs. Leaves are produced every 6 to 8 weeks and need about 4 weeks for maturation. Within this phase four developmental stages (A to D) can be distinguished by morphological characteristics.

The leaves are showing an expressed leaf age resistance to fungal attack. Stages A and B are generally susceptible to a high number of fungal pathogens, stage C is of intermediate resistance and stage D is not infectible by biotrophic leaf pathogens. In this study the influence of VAM inoculation, additionally to the indigenous VAM populations, plant growth, leaf development and resistance behaviour against Microcyclus ulei,the causal agent of the South American Leaf Blight, was evaluatd.

VA-mycorrhiza infected rubber trees reveal an increase in resistance against a foliar disease (South American Leaf Blight) caused by the ascomycete Microcyclus ulei. The lesion size and the production of spores of the pathogen were significantly lowered in VAM inoculated plants, whereas the number of lesions remained unchanged. This suggests that the resistance response of the plant is significantly influenced by VAM treatment and demonstrates that enhanced resistance is not due to inhibition of penetration or early growing phases of the pathogen but to the modification of late resistance responses.

The data presented here unequivocally show that the VAM-association causes physiological changes relevant to the resistance reactions in the leaves, even when no macroscopic modification of the plant can be seen.

The enhancement of the resistance of the plant along with the reduction of the pathogens spore production, here caused by a VAM-fungus, is an important epidemiological factor for the control of the South American Leaf Blight in rubber plantations of Brazil. The combination of VAM-inoculum with well designed plant management measures, crown budding, mixed cropping and the use of hyperparasites can lead to a complex system of integrated plant protection in Brazilian rubber cultivation.

1201 92 - 10/128

Plant protection

Asia, India, study, glasshouse, rice, leaf extracts, fungal pathogens

TEWARI, S.N. and M. NAYAK

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