Striga asiatica : a driving-force for dissemination of conservation agriculture systems based on Stylosanthes guianensis in Madagascar

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The high adaptability and practicality of these systems based on S. guianensis make that they are easily adopted by farmers. They represent 60 to 70 % of the CA/DMC systems extended in the middle-west of Madagascar, which disseminate rapidly (figure 2).

Mots-clés : Arachis pintoï, petite agriculture familiale, scv, systèmes agraires

Le contrôle du striga par les systèmes SCV

 ouvrage de vulgarisation | |    

Ce chapitre du manuel SCV en cours de rédaction à Madagascar décrit les moyens de contrôler le striga, plante parasite des cultures, grâce aux systèmes de culture SCV. Au sein des systèmes SCV la culture en association de plantes piégeuses du striga (qui déclenchent sa germination mais ne sont pas parasitées), des températures du sol moindres, la meilleure fertilité du sol, les conditions globalement favorables au développement des parasites du striga permettent de contrôler ce parasite. Les systèmes SCV les plus intéressants en zones infestées sont décrits.

Mots-clés : sorgho, désertification, agriculture durable, Adventices, gestion du sol

Impact of a DMC rainfed rice-based system on soil pest and Striga infestation and damage in Madagascar

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Direct seeding, Mulch-based, Conservation agriculture (DMC) systems are being extended in Madagascar in view of reducing erosion and loss of fertility of hill slope soils observed in conventional rainfed systems. However, little is known on their effects on infestation and damage to crops (particularly rice) by soil insect pests and Striga. While in the regions around Lake Alaotra and Manakara, dramatic damage by black beetles (Heteronychus spp.: Coleoptera, Scarabaeidae) was observed on rice cropped on mulch , attacks by these pests were reduced after a few years of DMC management in the Highlands of the Vakinankaratra region . On the other hand, in the Middle-West of Vakinankaratra, where Striga asiatica (Scrophulariaceae)has become a major constraint to staple cereal crop cultivation in rainfed systems, infestation of rice and maize by this parasite was drastically reduced after just one year of DMC management based on dead or live mulches, compared to the traditional plough-based system . The objective of the studies presented was to elucidate the factors accountable for reduction in infestation and damage by soil insect pests and Striga in DMC rainfed rice/soybean-based systems, with particular emphasis on its effect on natural enemies of pests.

Mots-clés : Riz, Arachis pintoï, Les Hautes Terres , Adventices, petite agriculture familiale, scv