Importance de la fusariose vasculaire du Pois (P isum sativum L.) dans l'ouest Algérien : pouvoir pathogène, races physiologiques et compatibilité végétative chez Fusarium oxysporum f.sp. pisi et essai de lutte biologique

Abstract

In the field, the cultivation of peas is attacked by many enemies including, fungal diseases are one of the main factors for the decrease in production. Surveys conducted in several fields of peas grown in four different agro-climatic zones in western Algeria (coastal plains, interior plains, plateaus and Sahara) at different phenological stages of the plant (seedling stage and flowering to pod formation) during agricultural companions (2007-2011), followed by laboratory analysis allowed the identification of a large number of fungal diseases and their geographical distribution. Among the pathogens we estimate: Ascochyta blight, root rot and crown rot, wilt-yellowing, mildew (Erysiphe sp.), Downy mildew (Peronospora pisi), we also note the presence of bacterial blight (Pseudomonas syringae), the Rust (Uromyces pisi) and (Botrytis cinerea). The laboratory analyse of the rhizosphere microflora showed the following range of fungi: Fusarium sp, Alternaria sp, Cladosporium sp, Epicoccum sp, Penicillium sp, Aspergillus sp, Pythium sp. Phoma sp, Phialophora sp, Helicomyces sp , Stemphylium sp, Gilmanila sp, Monilia sp, Rhizoctonia sp, Ascochyta pisi a diverse range of bacteria (Pseudomonas fluorescens /putida ,Pseudomonas aeruginosa ,Stenotrophomonas maltophilia, Xanthomonas sp., Erwinia sp.,Chryseobacterium meningoseptium, Enterobacter Cloacae , Chryseomonas luteola , Burkholderia cepacia , Photobacterium damsela , Serratia marcescens). The comparative study (quantitative and qualitative) frequencies of isolation, allowed us to distinguish significant differences. These results contribute significantly in improving knowledge of the interactions between the agents of the rhizosphere microflora and plant peas. From plants with visible symptoms of yellowing and wilting, sometimes associated with different aspects of rot, isolates from the crown and root, we were able to confirm the presence of Fusarium oxysporum f.sp.pisi. Results from this study revealed the existence of a significant morphological and pathogenic variability within the population of Fusarium oxysporum f.sp. pisi, we identified the existence of four physiological races (1, 2, 5 and 6) in west Algeria. The study of the organization of 21 isolates in the special form pisi from different geographical origin (western Algeria) and belonging to four races of FOP has revealed the existence of four VCGS, reflecting its genetic diversity. The biological test control against the FOP and FSP through the use of non-pathogenic isolates of Fusarium oxysporum native showed that they exert antagonistic activity "in vitro " by a fairly significant competition for occupation of space use and "in vivo " by a remarkable reduction of the index of the disease by induction of resistance in the pea plant. These results provide evidence of the antagonistic activity of non-pathogenic F. oxysporum isolated from the rhizosphere in the control of vascular wilt and fusarium foot Pea.