Organic Pest Control: Part 2


This month’s theme is Organic Pest Management!  There are dozens of pests out there that want to munch on your veggies as much as you do!  However, not all bugs in your garden are bad.  In fact, most of the bugs you will see will either be neutral or even beneficial for your garden.  Before killing a bug or spraying your plants, it’s a best practice to identify the insect in question.  Try these resources:

In the last newsletter, I discussed preventative measures for pest control.  This week, I will go over organic pest control sprays for gardeners.  This list will go from least toxic to most toxic.  While we tend to think of organic gardening as very safe, please keep in mind that any insecticide, even an organic one, can have impacts on the environment and human health.  Always read the full instructions and safety precautions before spraying anything!

Insecticidal Soaps & Horticultural Oils: Both options are relatively non-toxic and non-persistent, meaning they only work on direct contact with the insect.  These products work by clogging up the breathing pores on the bodies of insects like aphids, earwigs, grasshoppers, leafhoppers, mealybugs, sawfly larvae, scales, spider mites, and whiteflies.  Generally, this is a good option for soft bodied insects, but pests with thick shells are often not affected.

Neem Oil: This is a specific type of horticultural oil that works as described above, however, it is also a mild fungicide and is worth noting for this double effect.  It can be used in rotation with liquid copper and/or Serenade.

Bt (Bacillus Thuringiensis): This is a type of bacteria that only kills caterpillars.  This means that it will not harm other types insects in the garden, but you do need to be careful to spray when there is no wind to avoid drift onto plants that host friendly caterpillars.  This is very effective for cabbage worms, tomato horn worms, corn borers, squash vine borers, and other caterpillar pests.  The caterpillars must ingest the Bt, so you can spray the plant leaves and not worry about directly hitting the insects.

Spinosad: This is the next level of organic spraying, where the chemical becomes more broad spectrum (meaning it is more likely to kill beneficial insects if misused).  Spinosad is an insect neurotoxin derived from a bacteria that is effective against Colorado potato beetles, corn borers, ants, fire ants, beetles, caterpillars, worms, fleas, leafminers, spider mites, thrips, codling moth, and other insects.  It is best used in rotation with Bt to control caterpillar infestations.  Spinosad can only be sprayed a limited number of times per year and does have a re-entry period of 4 hours.  Spinosad breaks down in sunlight, so is best sprayed at night.

Pyrethrin: Derived from chrysanthemums, this is a broad spectrum insecticide labeled for use against hundreds of pests.  Consider this your “nuclear option” when all other preventative measures and sprays have failed.  In my opinion, if you need a “nuclear option” then you are probably better off removing the infested plants from your garden.  Something is wrong, the plants are either old or stressed in some way and you are better off getting them out of your garden entirely.  Wait a few weeks and replant, if it’s the appropriate season for it.

Again, whatever you decide to use in your garden, read the labels before spraying, wear protective clothing, and take measures to prevent killing beneficial insects!

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