This week at Nourish the Planet I continued my research into bio pesticides. Pest management is an integral part of growing plants and especially so when we need them to nourish us. Many plants contain compounds which they continued my research into bio pesticides. Pest management is an integral part of growing plants and especially so when we need them to nourish us. Many plants contain compounds which they use to deter herbivory; humans can extract these compounds and apply them to plant bodies to help eliminate pests. Last week I described the use of Neem oil as a natural insecticide, and this week I will discuss the use of garlic/onion extracts to manage pests.
Garlic is widely recognized as a useful pesticide, and is in fact an active ingredient in some commercial pesticides. There are several components of garlic oil which are biologically active and many contain sulfur. The sulfur-containing compounds present in garlic (and related plants including onion) have been shown to exhibit antimicrobial and antifungal properties as well as insecticidal properties and this seems to be due to the cytotoxic effects of the sulfur compounds.
Garlic has been shown to deter a variety of insects at all stages of their life cycle including aphids, white flies and mites, as well as disease-causing pathogens and nematodes. Unlike Neem oil; which is generally safe for beneficial insects like ladybugs garlic is not selective. It will kill beneficial insects as well as pests and the consulted literature implied that garlic should not be used against aphids because it will kill ladybugs and other natural predators.
Since beneficial insects are generally absent in an indoor Aquaponics or Hydroponics systems, garlic oil has the potential to be a particularly potent and appropriate biological pesticide here at Nourish the Planet. Also, Neem oil is toxic to fish and so has very limited use in Aquaponics systems whereas garlic oil has traditionally been used in aquaculture.
Garlic can be applied alone but most of the information I found involved boiling it with pepper and sometimes onion. The chopped mixture is then strained and the resulting liquid is applied to the plants.
Since Nourish the Planet is in the process of moving many of our systems have been temporarily taken down. I am planning to whip up a batch of garlic/onion/pepper spray to have ready if we need it once things are up and running again!
Emily Hanna – 6/16/2014