Parthenium hysterophorus, commonly known as Santa-Maria weed, is a notorious invasive species globally. It is toxic to crop germination and growth, leading to a nearly 25% reduction in crop yields in the least developed countries. This weed has significant socioeconomic impacts on human health, soil fertility, biodiversity, and agricultural productivity in Ethiopia. Currently, synthetic chemicals are widely employed to manage this weed. However, their frequent use poses numerous risks to human health and the environment. Herbicides like Roundup® are non-selective and affect all plant types. Conversely, allelopathic plants and their derivatives are emerging as promising sources for natural herbicide development. In this study, the root of Echinops kebericho was selected for its rich history of diverse biological activities against Santa-Maria weed. The crude ethanol extract of E. kebericho root completely inhibited the seed germination of Santa-Maria weed at a concentration of 0.05 mg/ml in vitro. Following a bioassay-guided protocol, the crude ethanol extract was further partitioned using hexane, CHCl3, and MeOH, and screened against the weed. The hexane and CHCl3 extracts exhibited 100% inhibition of Santa-Maria weed seed germination. Dehydrocostus lactone, isolated as an active compound from the nonpolar fractions, achieved 100% inhibition of the weed's germination and growth

Dehydrocostus lactone, Parthenium hysterophorus, phytotoxicity

In conclusion, organic agriculture needs natural herbicides that are nontoxic, easily biodegradable, and environmentally friendly. This study investigated the herbicidal potential of E. kebericho against the allelopathic Santa-Maria weed. The in vitro results showed that the CHCl3-soluble portion of the ethanol extracts from E. kebericho completely inhibited seed germination at a 0.05% concentration. When tested on 15-day-old seedlings under greenhouse conditions, only the CHCl3 extract of E. kebericho effectively suppressed the growth of Santa-Maria weed seedlings by 92%. Dehydrocostus lactone, isolated from the root of E. kebericho, was identified as the active principle against the target weed. It demonstrated comparable phytotoxic activity (92%) to the well-known herbicide Roundup®. In our efforts to study its selectivity towards various cereal crops, including pea, chickpea, niger, linseed, maize, wheat, tef, barley, sorghum, common bean, and faba bean, we concluded that Dehydrocostus lactone is selective to all these cereal crops. However, it showed minimal phytotoxicity on common bean, faba bean, maize, and wheat at an early stage after application. Therefore, Dehydrocostus lactone stands out as a promising natural herbicide candidate for managing P. hysterophorus weed

Zelalem Gizachew, Negasa Dechasa, Shashitu Bedada, Takele Gudeta, Melaku Alemu and Suh Christopher (2024). Dehydrocostus lactone: A natural herbicide against the Invasive Weed Parthenium hysterophorus. International Journal on Emerging Technologies, 15(2): 19–25.