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Sunday, April 16, 2017

Aphids Versus Soap and Water: a Never Ending Battle

Q. First year with my apricot and I spray with soapy water to control aphids. Every day I check leaves but they never stop. Is this good to spray to use?
Adult aphid. These are about the size of a large grain of salt. There are about 200 different aphid types and most of them only prefer a specific plant. A few of them are general feeders but most are very specific to what they like to eat.

A. Soap sprays are good to make an immediate kill of an insect and don't expect them to reestablish themselves after you're finished. The problem with aphids this time of year is that they will come back, usually in just a few days, after soap sprays have been applied.

Aphid feeding on plum leaves can cause the leaves to curl over time, thus protecting them from sprays.

Dr. Bronner'sOrganic Castile Liquid Soap Almond
I am not a big fan of soap and water sprays for insect control
but if you decide to make your own please use a
Castile type soap free of any scents or lotions.

Use a decent soap

The good thing about soap sprays is that they are very safe for humans, pets and other large animals. The bad thing about soap sprays is they do not discriminate between good bugs and bad bugs. If it's a bug and you spray it, it will die, good or bad.

Soap and water is a killer

            The second negative about soap sprays is they have no residual. That means that soap sprays leave nothing behind to kill bugs after the spraying is done. They have no residual. You are the residual. Soap sprays rely on you, the applicator, re-spraying when needed.
            You must be knowledgeable enough to spray the bad bugs but not the good bugs. It also requires that you find most, or all of the bad bugs when you spray. If you don't, they reestablish in a few days and you must spray them again, and continue to spray them as long as you need to, over and over, until the problem is gone.

More about aphids

            Aphids began infesting new growth, making more babies, as soon as the leaves popped out. Females that survived and made it through the winter on landscape plants had wings. They flew to the soft, succulent, sugary new growth and started laying eggs as soon as it came out and as fast as they could. What a good mother!
Ladybird beetle with aphid

            Mature female aphids that make it through the winter have wings. They can fly short distances to the new growth. These mother aphids never need a male aphid to produce their young and they produce young very rapidly.
Aphids on developing pomegranate fruit. The fruit tissue is pretty hard for them to feed through but they will certainly like the much softer leaves and flower petals

            It just so happens that many ants like the sugary residue that aphids leave behind when they are feeding. Those ants which use sugar for raising their young absolutely love aphids and move them to different locations on plants so that they can "farm" them. Controlling ants colonies also helps to control aphid populations.

Chemical controls

            Moving up the line of toxicity to aphids and comparing it to the toxicity toward humans and the environment, next try some of the oils such as neem oil, rosemary oil, mint etc. next moved to the so-called "organic" or "natural" sprays like pyrethrins.

            Pyrethrins are made from a type of chrysanthemum. If you feel safe with pyrethrins, you may choose to move to the synthetic pyrethrins which are everywhere in garden stores but are not considered "natural" or organic. They leave behind a residual and continue to kill insects after they have been sprayed.

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