Crop protective effects of formulated neem and karanja oils on cucumber and cannabis plants

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Agricultural crop plants require a range of intensive agricultural inputs, such as pesticides, growth regulators,fertilizers and other synthetic and organic products. The organic production of food plants requires a carefulassessment of all possible avenues for pest and disease control, and efficacy data and modes of action need tobe well studied. Sources of organically-certified products for disease control in Canada are currently limited toa few well-known and widely used materials that include formulations of bacteria and chelated chemicals.Plant extracts have attracted wide interest but the consistency and stability of the product has not enabled theirwidespread use. Plants naturally contain a wide range of phenolic compounds, terpenoids, flavonoids,phytoalexins and other chemicals that have potential antifungal properties. In this research, formulated extractsderived from the Indian neem tree (Azadirachta indica) and the Karanj tree (Pongamia pinnata) will be testedfor management of two important fungal pathogens affecting greenhouse cucumber plants, and which havebecome recent limiting factors to production of medical cannabis (Cannabis sativa L.) also grown ingreenhouses. These tree species contain high levels of tetranortriterpenoid (limonoids) in seeds, leaves and bark(neem) as well as high levels of flavonoids (karanja) in seeds. The invitro toxicity of these formulations will betested against mycelial growth and spore germination of the two pathogens. This will be followed byassessment of temperature and pH effects on product activity. Greenhouse experiments will evaluate whetherthe formulations have activity on plant growth (measured as height and dry weight) as well as disease reductionon the roots (Fusarium) and leaves (powdery mildew) of the two plant species. The research will investigatewhether induced levels of phenolic compounds, antioxidants and signalling molecules such as jasmonic acidand salicylic acid, are increased in treated plants. The results will provide additional insights into themechanisms of how these plant-derived products can affect plant growth and provide additional opportunitiesfor organic uses of plant extracts for protection of valuable horticultural crops in Canada.