Saturday, July 14, 2012

Saturday Short Subjects: DIY Insecticidal Soap

For much of this year, as a member of the 2012 Class of the U Conn Extension Master Gardener Program, I have been immersed in the study of plants, their habits, their uses, and their problems. Having completed the course work requirement of my training, I am out in the field volunteering as an intern, and staffing the county extension office under the supervision of my mentor Rachel. In the extension office, Master Gardeners (and supervised interns) answer questions, study samples mailed in or dropped off by clients, report suspected outbreaks to the proper authorities, and dispense advice.

The other day I submitted some sample cuttings from my friend’s rose bush, which were covered with some lively little critters and lots of white fluffy-looking matter. Many other plants in the yard, of several different species, had the same problem. Rachel and I looked under the microscope and, after consulting a number of books and then googling for images, determined that the critters were clearly aphids, soft-bodied sucking insects. Also known as “plant lice,” their most distinguishing identifying feature is the two short cornicles, or tubes, which extend from the end of their body. The ones on the rose sample were of the wooly aphid variety. There are over 1,375 species of aphids in the U.S. and Canada.

Rachel suggested that my friend spray the affected plants with insecticidal soap, repeating every few days, until the aphids disappeared. The soap works by drying out the aphid’s protective outer membrane, or cuticle, and entering their vulnerable cells.

There are a number of products commercially available, but many home gardeners make their own. Here is one such recipe: Nearly fill a clean 1-qt. spray bottle with water. Add 4 tablespoons of Ivory liquid (or some other very mild soap) and mix well. That’s it.

This recipe has many variations. Some call for the addition of other ingredients. Several recommend Dr. Bronner’s, but those recipes call for less soap. The key is to use MILD liquid Soap, NOT detergent, and not too much, or you might harm the plant or the neighboring vegetation. Watch for any damage to the plant, and cut the amount of soap by half immediately if you find some.

This soap is effective on any aphids (including the bright red ones we also saw in huge quantities in my friend’s yard) and other soft-bodied insects. 

Go get ’em, my friends. Happy hunting. 

Stay cool. And have a great weekend.

Why Saturday Short Subjects? Some readers may recall  being dropped at the movie theater for the Saturday matinee — two action-packed feature films with a series of short subjects (cartoons or short movies, sometimes a serial cliffhanger) sandwiched in between. Often the short subjects were the most memorable, and enjoyable, part of the morning. That explains the name. The reason behind these particular posts is that we are all short on time. My Short Subject posts should not take me as long to write or you as long to read (or try).

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