Pest Control

How Natural Pesticides Work and Can Help Your Garden

Let’s face it, if you are growing anything, indoors or out, you will eventually have to deal with pests. There are many organic growers with whom I work that insist they do not use any pesticides. However, when I finish explaining what a pesticide is, they realize they do use pesticides, just not synthetic ones. The misuse of terms occurs on both the organic and conventional (non-organic) sides of growing. Many conventional growers think that organic growers just let their plants grow and do not use any pesticides; hoping nature will run its course.

It is a bit frustrating to see tests at universities where plots are labeled “organic”, meaning they did absolutely nothing (sometimes not even fertilizer!), and one plot “treated” where they applied various pesticides, fertilizers, etc. It is hard to believe that this myth about organic agriculture is still perpetuated by universities today. There are many natural pesticides that organic and conventional growers can use. In reality, good organic growers don’t just sit there and watch their plants die because of a pest infestation, they do something about it! I contacted several organic growers and asked them what they use for pests. Below are some of the most common approaches they take when they have problems.

Prevention Through Management

Like humans, plants have several growing requirements. These include proper nutrition, proper amounts of water, sun or light exposure and proper temperature. If any of these go out of whack, the chances of getting sick increase and the ability to fight off the sickness decreases exponentially. Simple things like planting a shade-loving plant in direct sun and not giving it enough water will stress the plant so much it become more susceptible to pests. Likewise, over-watering plants (tomatoes for instance) will result in fusarium wilt and white fly outbreaks. Changing temperatures in a greenhouse too quickly or slowly will result in leaf minor. Adding too much or too little nutrition will also result in a sick plant. Sick plants emit a different color spectrum, enabling pests to see them resulting in various pest infestations. Prevention of problems such as these are possible by paying attention to the plant’s needs for watering, nutrition, light and air movement, allowing for you to avoid having to use pesticides in the first place.

Managing for optimal plant health also includes preparing the soils properly. This often involves incorporating organic matter to help achieve the highest possible levels in the soil. Soil health has an amazing impact on the health of the plants. High levels of organic matter create a chain reaction of benefits for plants. Organic matter is increased through biology (worms, microbes, fungi, etc.), carbon materials (compost, humic acids) and plant materials. By managing soil health, you are preventing/mitigating many potential problems that would be caused by stressed plants.

When pest outbreaks do occur, there are several options; some are safe and some are not. Pesticides are not all highly toxic to people or the environment. There are safe alternatives. Here are some of the less-toxic solutions that are effective and require little or no safety precautions when used. Carefully read the labels before you purchase or use these products. Even though they are natural, some of them can still get people or animals sick if used improperly.

Insecticidal Soaps & Oils

Insecticidal soaps work on soft bodied insects but only by coming into direct contact with an insect. The soaps use fatty acids to disrupt the structure and permeability of the insects’ cell membranes. The cell contents leak from the damaged cells and the insect quickly dies. Soaps are diluted in water and sprayed on soils and on plants.

The following essential oils all have known pesticidal properties: Rosemary, Peppermint, Clove, Lavender, Tea Tree, Pine oil, Thyme oil, Orange oil, Cedarwood, Hyssop, and Cintronella. There are also two oils from trees in India that have pesticidal properties that have been known for hundreds (if not thousands) of years. They are Karanja and Neem. Neem oil contains azadirachtin as an active ingredient. Azadirachtin has been found to be very effective for over 600 species of insects. Karanja Oil is extracted from seeds of the Karanja Tree (Pongamia glabra) which is commonly found in India. Karanja Oil is used in agriculture and pharmacy just like neem oil. It has similar insecticidal properties as neem oil and acts against a number of pests and insects. Some oils, such as orange oil, can eat through the exoskeleton of hard bodied insects, leading to their demise. The oils are mixed with soap, witch hazel, or alcohol and water and sprayed on the plants and soils to control pests. Applications are made on a regular basis during the growing season.

Integrated Pest Management

Biological intervention is an option for controlling pests through a process known as Integrated Pest Management (IPM). Common IPM strategies use beneficial insects such as lady bugs for aphid control or parasitic wasps for whitefly control.  IPM programs are in use in many farms, golf courses and public areas. These programs involve using insects, plants, birds and other organisms to control pest populations.

Many beneficial microorganism products also make great biological pesticides. The Bacillus species is well-known as an anti-fungal for several types of fungal problems both on soils and plant leaves. Trichoderma is a fungus that is colonizes roots and is a potent anti-fungal. Some other lactobacillus species are effective controls for various fungal problems such as Rhizoctonia, Pythium, and Fusarium. There are hundreds of naturally-occurring, NON GMO microbes that have a variety of pesticide applications. After all, the natural way microbes work is through a process known as competitive exclusion. Microbes can come in powders or liquids and can be spread on soils or sprayed on leaves. Many can be mixed with oils and soaps as well. Due to their short life span, it is best to apply them on a regular basis. And, it is often a good idea to mix diverse species to get broader effects.

Diatomaceous Earth (DE) is a well-known pesticide. It is the skeletons of microscope organisms. The sharp edges cut into soft-sided insects that rub against it, causing them to bleed to death. DE is great for grubs. It can be applied in a liquid through a sprayer or spread out dry using a fertilizer spreader.

Management is best form of prevention. However, when problems arise, it is good to know there are several options, especially safe and effective ones.

Eric Lancaster is Executive Vice President of TeraGanix, Inc.

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