Onion (Allium cepa L.) purple blotch caused by Alternaria porri (Ellis) Cif. is a disease of world-wide importance. The aim of this study is to evaluate the effectiveness of treatment combinations with fungicides and plant-based pesticides in the control of A. porri, onion growth and bulb production. To do so, the effect of aqueous extracts (5%, 10%, 15%) of Lippia multiflora, Azadirachta indica and the fungicides Mancozeb 80 WP (1g/L) and Azoxystrobin 250 SC (0.2%) on the radial growth of A. porri on Potato Dextrose Agar (PDA) medium was assessed. Furthermore, the onion variety «Prema» was used in field in a Fisher block design with four replicates. The treatments included the following: (i) the application of foliar sprays with distilled water (control), Mancozeb at 2 kg/ha and Azoxystrobin (1L/ha); (ii) the ground application of plant leaf powder (400 g/m2) at seven days before transplanting, which was then followed by the application of aqueous plant extracts and fungicides as foliar sprays. Sprays were carried out at 60, 80 and 100 days after transplanting. The results show that treatments inhibited the growth of A. porri from 25.35 to 100%. Furthermore, bulb yields in the plots treated with plant powders, ranging from 35 to 43.25 t/ha, exceeded that of the fungicide Mancozeb, which was 28.75 t/ha. From these findings, soil and leaf treatments with plant extracts may be used in the control of onion purple blotch disease. Nevertheless, it is essential to study the effects of plant extracts on soil fauna and microorganisms.