Jan
08
2013

Least Toxic Pest and Disease Control Sprays

When looking at spray options in relation to pest management, it is important to look at what you are trying to achieve.  If you are growing fruits, vegetables, or greens; the least “toxic” approach is always best.  Over the years a number of products have been developed to combat the various pests in the garden, with some having more successful than others.  With all the choices these days on the shelf, here is a breakdown of some of the least ”toxic”, successful alternatives…

 Neem:

Neem Tree

Neem Tree

Neem is a botanical insecticide derived from a tree native to India.  Azadirachtin is the active constituent of neem, and is the substance responsible for its growth inhibiting properties.  This compound disrupts the insects reproductive life-cycle, and decreases the insect population.  It does work a little slower than other pesticides, and needs repeated application.  Most folks use neem in conjunction with another pesticide because it shows little effect when applied alone directly on insects; except in mixed oil formulations. It is important to note that most insects are affected only after consuming foliage that has been treated.  This is one reason many folks have begun using Azadirachtin for its systemic properties, as part of a successful preventative strategy.  There are several potent Azadirachtin products that work great for this application.  While the main use of neem is to fight insect pests, it has the ancillary effect of preventing powdery mildew.  It is not the best option for combating mildew alone, but used regularly should help keep powdery at bay.  Neem is a great option because it safe for mammals, it doesn’t disrupt beneficial insects and has a long history of safe use.   It is called the miracle tree for a reason.

Here is a great preventative spray recipe that works!  Used once a week until fruiting starts:

Safer Insect Killing Soap @ 45 ml/gal
Einsteins Oil (or other cold pressed neem oil) @ 15 ml/gal

Insecticidal Soap:

Safer Insect Killing Soap

Safer Insect Killing Soap

Soaps can be used to control a wide range of plant pests. Small, soft-bodied insects such as aphids, mealy bugs, thrips and spider mites are most susceptible to soaps. In most cases,
control results from disruption of the cell membranes of the insect. Soaps and detergents may also remove the protective waxes that cover the insect, causing death through excess loss of water. Insecticidal soaps act strictly as contact insecticides, with no residual effect. To be effective, sprays must be applied directly to, and thoroughly cover, the insect. Insecticidal soaps are considered selective insecticides because of their minimal adverse effects on other organisms. Ladybugs, green lacewings, pollinating bees and most other beneficial insects are not susceptible to soap sprays. Predatory mites, however, are vulnerable to insecticidal soaps.

Insecticidal soap is another great non-toxic option, that is effective when used properly.  It is important that the soap make contact with all the pests because it is only effective on contact. Make sure to spray when the lights are off and make sure the leaf surface is dry before the lights come back on.  Do not use with sulfur.

Horticultural Oils:

Various oils have been used for years to manage certain pest problems (e.g., scale, aphids, mites) on fruit trees, shade trees and woody ornamental plants. Several recently developed oils extend this usefulness to flowers, vegetables and can control some plant diseases, such as powdery mildew, and insect pests like spider mites.  Horticultural oils block the air holes through which insects breathe, causing them to die via asphyxiation.  They may also act as poisons, killing them.

Einstein Oil

Einstein Oil

Some of the latest advancements in pest management have come in the development of horticultural oils.  Gardeners are finding success with clove, rosemary, thyme, geranium, and citronella oils to name a few.  Two companies to look out for our Sierra Natural Science and Greenway Nutrients, both companies have developed effective, non-toxic horticultural oils that can fight insect pests, powdery mildew, and other fungal pathogens.  All of their products have been tested in the field and they work.

Oils pose few risks to people or beneficial insects, however, be warned when applying horticultural oils, they quickly dissipate through evaporation, leaving little residue. Oils also are easy to apply with existing pesticides to extend and enhance their performance.  The main limitation of horticultural oils is their potential to cause plant injury (phytotoxicity -  a toxic effect by a compound on plant growth. Such damage may be caused by a wide variety of compounds, including trace metals, pesticides, salinity, phytotoxins or allelopathy), in some situations, especially when used in conjunction with sulfur products; such as vaporizers or sprays.

The most successful gardeners have found that a solid, regular, preventative practice is the best option to keep pests at bay.  By making the environment inhospitable to pests, your likelihood of succumbing to a pest outbreak diminishes.  Switch between types of spray so the pests and diseases don’t become resistant and don’t get lazy.  These are safe, non-toxic, and effective tools for the discerning garden.

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