Alternative control of littleseed canary grass using eucalypt oil

Abstract

Globally, huge amounts of synthetic herbicides are used to manage weeds in arable lands. However, their widespread use has resulted in various toxicological effects on the environment and human health, besides resulting in the emergence of herbicide-resistant weed biotypes. To overcome these problems, there is an urgent need to search for novel compounds, particularly natural plant products, with potential herbicidal activity. In this area, we studied the phytotoxic effect of volatile oil from lemon-scented eucalypt on littleseed canary grass, a noxious weed of wheat fields. Our findings show that under laboratory conditions the emergence and earlier growth of the weed decreased and completely ceased using a very low concentration of eucalypt oil (0.0714%, v/v). Treatment with eucalypt oil of the 4-week-old pot-raised weeds caused visible damage such as chlorosis and necrosis, wilting and even plant death. The effect was concentration-dependent. At low concentrations, 2.5 and 5%, v/v of eucalypt oil, plants were damaged but recovered later, whereas at concentrations higher than 5%, v/v, of eucalypt oil plants showed severe injury with little or no sign of recovery, and death. There was a severe effect on the photosynthetic and respiratory ability of treated plants 7 and 21 days after treatment. Eucalypt oil treatment caused a rapid electrolyte leakage in the P. minor leaf tissues, indicating a loss of membrane integrity. The study concludes that lemon-scented eucalypt oil offers a good option for control of littleseed canary grass and could be included as a viable component of integrated weed management under sustainable agricultural practices.