No abstract

In this study we tested the possibility that foliar-applied caraway or peppermint essential oils (EOs) can selectively inhibit the growth of Echinochloa crus-galli (a typical maize weed) but not that of maize plants, attempting to develop an eco-friendly botanical herbicide.We tested the phytotoxic potential of oil-in-water emulsions of each EO with addition of commercial adjuvant mainly composed of fatty acids methyl esters, studying their effect on 2 visible plants injuries, biomass accumulation, chlorophyll a fluorescence and changes to biochemical patterns of both the main crop (maize) and the weed (E. crus-galli) via an untargeted metabolomic approach. We found that oil-in-water emulsion containing 2.5% of adjuvant and of caraway EO did not affect significantly the growth of maize plants, did not induce foliar symptoms and did not alter the status of the photosynthetic apparatus, as revealed by chlorophyll a fluorescence. On the contrary, this emulsion exerted significantly negative effects against E. crus-galli growth, inducing foliar injuries and reducing the photosynthetic efficiency of photosystem II. We also found that the studied emulsions caused a series of biochemical changes in the plant tissues, with caraway emulsion being more phytotoxic, as compared to the peppermint EO-emulsion. We conclude that oil-in-water emulsion containing 2.5% of caraway EO could be used in future as a foliar-applied botanical herbicide against E. crus-galli in maize cultivation.

No abstract

This review article discusses the active constituents and potential of two menthol mint oils, Mentha piperita (MPEO) and Mentha arvensis (MAEO), as natural sources for botanical pesticides. The biological activities of these menthol mint oils, which can be useful in agriculture, have been broadly researched, especially toward phytotoxic microorganisms. To a lesser extent, the insecticidal and herbicidal activities of mint EOs have also been studied. It is apparent that the prospect of using menthol mint oils in agriculture is increasing in popularity. A number of investigations showed that the in vitro efficacy of MPEO and MAEO, as well as that of their main constituent, menthol, is pronounced. The results of in vitro research are useful for choosing EOs for further investigations. However, it is clear that in situ experiments are crucial and should be more extensively developed. At the same time, known techniques are to be applied to this area and new methods should be worked out, aiming at the improvement of EOs’ pesticidal efficacy and cost-effectiveness, for future implementation in agricultural pest control.