Preliminary evaluation of Septoria urticae Rob et Desm as a biological control agent of Urtica urens L

Abstract

Summary — Plants of Urtica urens L (annual nettle) showing symptoms of severe foliar necrosis were collected in the horticultural belt of the city of La Plata (Province of Buenos Aires, Argentina). The agent causing the disease was identified as Septoria urticae Rob et Desm. Due to the severe lesions caused by the pathogen, its potential as a biocontrol agent of U urens was studied. Routine phytopathological techniques were used in order to evaluate the bioherbicide potential of the pathogen in the greenhouse on plants of U urens and other species of the Urticaceae family, such as Boehmeria nivea (L) Gaud, Pilea cadierei Gagn et Guil and Parietaria officinalis L. Using variance analysis it was shown that the pathogen caused a high percentage of defoliation and a reduction in dry weight (DW) of nettle plants, apart from significantly diminishing the seed production (number and DW) in the greenhouse. B nivea and P cadierei did not show any symptoms of the disease, whereas P officinalis was slightly affected by the fungus. This study suggests that the pathogen could play an important role as a biocontrol agent since it reduces U urens production.