Due to food security issues and weeds problem in rice production, allelopathy is introduced as an alternative towards sustainable weeds management. One of Myrtacea plants known as Melaleuca cajuputi extract is studied to assess its herbicidal or allelopathic effect on notorious paddy weeds known as barnyard grass. The plant extract of Melaleuca cajuputi is extracted using supercritical carbon dioxide extraction and soxhlet extraction. The chemical composition of the extract is determined using gas chromatograph mass spectrometry analysis and it was reported that caryophyllene and humulene are detected as the two major sesquiterpenes present. The effectiveness of the inhibition of the weeds was also studied and compared with conventional herbicides and caryophyllene standards. It is determined that Melaleuca cajuputi extract of supercritical and soxhlet extraction induces visible injuries towards the weeds at bud stage of less than 0.75 cm. Thus, it is recommended to increase the concentration higher than 0.05 M to suppress the weeds that grown. Melaleuca cajuputi oil can be further studied to be a potential source for bio-herbicides. © 2018 Elsevier B.V.