Etiologia do damping-off na cultura do coentro no município de Arapiraca-AL e efeito na interação dos patógenos na incidência da doença

Abstract

Coriander is a native culture of the eastern Mediterranean and southern Europe, it is used as a medicinal and aromatic plant. In Brazil, coriander has a great economic importance, generating income for many families, particularly for the Northeast Region, which now accounts for more than half of the national production. Coriander farming is an activity that still presents risks, for being a sensitive crop to attack disease-causing microorganisms, mainly those of fungal origin. Nowadays, one of the main phytossanitary problems for coriander is the occurrence of damping-off causing a significant reduction in production, by be levied on plant tissues young and newly planted seeds, causing necrosis in the roots, soaked lesions and yellowing. Consequently, the objective of this study was: identify the etiological agents responsible for "damping off" of Coriander culture in the city of Arapiraca - AL. Soils were collected in four producing areas, and it were used for planting coriander in pots with a capacity of 250 ml to display symptoms. From the symptomatic plants were performed isolations of pathogens and their identifications, through molecular analysis with specific primers for RBP2 genes, ITS, TEF and “Morphocultural” analysis. Tests were conducted to evaluate the interactions between pathogens Fusarium, Pythium and Rhizoctonia in the germination and seedling damping, as well as the effect of the incorporation of infected coriander seedlings incorporated into the soil after the first test. Seven pathogenic isolates were obtained from three genus Fusarium, Pythium and Rhizoctonia. The species, Fusarium inflexum, F. lacertarum, F. falciforme, Pythium irregulare and Rhizoctonia solani, were identified as responsible for coriander seedling damping-off in Arapiraca-AL region. This is the first report of F. inflexum, F. lacertarum, F. falcifome and P. irregulare causing damping-off in coriander seedlings in the world. This is the first report of R. solani causing coriander seedling damping-off in Brazil. The simultaneous inoculation F. inflexum, P. irregulare and R. solani, increased incidence of damping off and reduced stand coriander seedlings. The incorporation of infected coriander seedlings and subsequent coriander cultivation decreased the germination percentage and increased the incidence of tipping.