Epidemiologia de doenças radiculares na cultura do coentro no Município de Arapiraca-AL

Abstract

Coriander is one of the most cultivated vegetable crops in Arapiraca region-AL, Brazil. Its crop is widely accepted on the market and it provides the return of the capital invested between 30 and 40 days after planting. In recent years, producers have reported a drop in the coriander production due to the plant death, especially during the first days after seedling emergence. It is observed necrotic lesions on the roots and on the stem rot portions. It has been suspected that the problem is a biotic disease caused by a complex of microorganisms; however its etiology is still unknown. There’s no estimation about the importance of this disease, since in severe cases it can lead to the abandonment of production areas, causing a socioeconomic problem. Thus, this study aimed to estimate the importance of this disease in the countryside of Arapiraca city through the study of the prevalence, incidence, and spatial spread of this disease in the beds and in the temporal progress. Different coriander fields were survey between February and December, 2012 in order to estimate the incidence. All plants presenting necrotic lesions in the portion of the stem and/or damping off was considered a sick plant. Three beds were examined in each field for sick plants. The number of fields assessed in each plot was according to the parameter evaluated: prevalence = 50 fields; incidence and distribution space = 10 fields and areas temporal progress = 2 fields. It was observed that the root rot and stem rot is widespread and has been found in 84% of the fields. The average incidence in the beds was 23% (5% to 58%). The spatial pattern of the disease was regular within the beds. It was observed a raised of 275% in the disease progress rate between the first and the third cycle when it was used successive cycles of culture.