"The synthetic compounds were so powerful that we stopped looking for natural pesticides."
Some modify the plant's ability to produce natural pesticides while others affect the nutritional value of the crops themselves.
The city is using Anvil, similar to a natural pesticide produced by chrysanthemum flowers.
Finally, natural pesticides, though potentially harmful, do not build up in the environment.
For them, natural pesticides - which can control as many as 38 plant and animal pests, according to their proponents - are an answer.
Plant pesticides, fly ash and lime have also shown promise as a natural pesticide.
Where kusimanses live near human populations, they are "seen as natural pesticides."
But organic farmers do indeed apply toxic natural pesticides.
How do they test for the thousands of natural and synthetic pesticides on each product?
It has shown antifungal activity and was tested as a natural pesticide.