Plant Pest Control

Plant paracites are inevitable in the garden and may result in leaf damage and defoliation of the plant. In the past I used chemical agents such as Chlordane, DDT and Sevin. Subsequently I have seen the light and use much less toxic agents such as soap. The active ingredients are potassium salts of fatty acids also known as soap salts. This solution is not toxic to the plant and breaks down without leaving toxic residue in the soil. The soap works only when wet and loses its effectiveness after it dries. Plant watering washes away most of the residual soap. As you will see it is effective in controlling soft bodied insects and pests like these mealybugs. Mealybugs are insects of the Pseudococcidae family.

Croton leaf with mealybugs overwhelming the plant.

Plant mealybugs terminated after one application of soap solution. (~ 40X magnification, incident lighting)

How to make soap insecticide for insect control at home:

Make your own solution at home. Purchase a bar of unscented lye soap. (About $3.50) Grate about one third of the bar and add it to about double the volume of hot water. Gently stir until dissolved as much as possible. This makes 12 oz (1200 ml) of saturated solution. Don’t be surprised if it doesn’t all dissolve. Place this into a storage container with a cover for further dilution down to 1 to 2% solution. For application use an 8 oz (700 ml) hand held spray bottle fill it nearly full of water and add a teaspoon (5 ml) of the saturated soap solution. Spray the plant on all sides with the diluted soap solution once per week or as needed. Repeat once per month for maintenance. Replace equal volume of tap water into the concentrated solution as it is deleted until any undissolved soap disappears. Remake the concentrated solution when the supply is exhausted. Depending on the amount used, this supply of solution from one bar may take years to deplete. There are numerous home recipes on the internet but the main ingredient is soap.

This shows the soap bar wrapper.

Discussion:

Before treatment look to see if the problem is the result of a soft bodied pest. I use the microscope. You can use a magnifying glass. This observation is made because the soap will do nothing against bacterial, fungal, viral or other parasites. The first line of defense may be to hand remove the pest. Trimming a leaf with early signs is easy. When hand removal is not possible then other agents may be used. Horticultural soaps also known as biorational pesticides can be used. These include horticultural oil and insecticidal soap sprays. Biorational insecticides are typically used to target soft-bodied pests like caterpillars, mealybugs, whiteflies, spider mites or aphids. They provide a relatively non-toxic alternative to conventional insecticides, with few ecological side effects.They can be used on indoor and outdoor plants, including vegetables. Before eating be sure to wash your produce. There are commercially available plant-derived insecticides like neem oil and pyrethrum, and microbial pesticides like Bt.  Even with commercial agents, repeat applications may be necessary to get the best results. Obviously I can check the leaves with microscopic observation to see the efficacy of the application. Again, you can use a simple magnifying lens. Be attentive to the weather conditions and the time of year. Cold will also act to control these insects.

Pesticides in home gardens

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#biorational #pesticide #soap #pests #aphids

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