Nonchemical weeding of medicinal and aromatic plants

Medicinal and aromatic plants are major crops of domestic and industrial interest. Medicinal and aromatic plants are increasingly organically grown to enhance profitability. However, the presence of weeds may lead to a decrease in both yield and quality. Therefore, nonchemical methods of weed control are needed. In this study, mechanical weeding, flaming, stale seedbed, and biodegradable mulch were tested from 2003/2004 to 2006/2007 on coriander, fennel, and psyllium. Biomass and seed yield were measured. The biomass of weeds remaining at harvest was also measured. Results show a high sensitivity of coriander, fennel, and psyllium crops to the presence of weeds. Stale seedbed excessively delayed sowing time, thus inducing negative effects on crop seed yields. As a consequence, seed yield was 40–90 % lower than in the untreated plots. On the other hand, mechanical weeding, flaming, and biodegradable mulch reduced weeds by 50–95 %.