Rosemary Oil Effective against Spider Mites

This is an interesting piece of research done in British Columbia using Rosemary oil against spider mites.The two spotted spider mite is a very common pest of ornamentals like Italian Cypress and tomatoes.

Researchers in British Columbia found that pure Rosemary oil and a rosemary oil-based pesticide was totally effective (100% mortality) against the two spotted spider mite, a common pest of many ornamentals, fruit trees and vegetables. Not only did it kill two spotted spider mites, Rosemary oil repels spider mites and makes it less likely for them to deposit their eggs on plants sprayed with this oil. It was demonstrated that a predatory mite, one that attacks two spotted spider mites, is more tolerant of rosemary oil. 

Spider mite, webbing and leaf miner damage on tomato

The big advantages to the use of rosemary oil is that fruit that was just sprayed can be harvested immediately with no waiting time. This is not true of conventional pesticides where there is a waiting time between the application of the pesticide and before you can pick the fruit. Laboratory bioassay results indicated that pure rosemary oil caused complete mortality of spider mites at concentrations that are not phytotoxic to the host plant. Moreover, rosemary oil and rosemary oil-based pesticides are nonpersistent in the environment. 

Journal of Economic Entomology 99(6):2015-2023. 2006 
doi: http://dx.doi.org/10.1603/0022-0493-99.6.2015
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