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by Michael O’Brien, Extension Master Gardener
Cold temperatures have been with us for a while. This causes our furnaces to run more frequently and that makes our homes less humid. That combination makes houseplants’ soil dry out quickly. All these factors put together make a perfect environment for spider mites.
These little mites are part of the arachnid family and a closely related species in the Tetranychus genus. Spider mites live in colonies and are generally found on the underside of leaves. They are less than 1/20 of an inch long which makes them very difficult to see with the naked eye. Cloudy days make it even more difficult to notice them when inspecting plants.
Spider mites cause damage by puncturing the plant’s cells and sucking out the contents. Spider mites also create webs. A generation of mites can complete a lifecycle in less than a week when food and temperatures are conducive. Many times, when spider mites are discovered on plants it’s already become an epidemic.
There are some indicators to look for that help determine whether a plant has spider mites. One of the first signs is stippling on leaves. The term stippling means there are little white dots appearing on leaves. Next, the plant begins to develop many bronze leaves that quickly turn yellow, followed by leaf drop. The third phase, webbing, is noticeable on the leaves and stems as seen in the picture above. It is very important to wash your hands before touching any other plants. As these mites are very small and can appear transparent, it’s a good idea to have a 10x magnifier loupe, or greater, to see these pests. Click here to see an inexpensive loupe.
Spider mites can be very damaging to a plant and in extreme cases can kill the plant. When it comes to treating the plant, there is a difference between outdoor plants versus an indoor plant. There are many beneficial insects outdoors that will feed on the mites. Indoor plants don’t have these beneficial insects to keep the mite’s life cycle in check. These mites can be passed on to another plant quickly and easily just by touching the plant, clothing rubbing against leaves or a pet coming into contact with your plants.
Before treating an indoor plant it’s a good idea to use a loupe to gauge the extent of the outbreak. This way it is easier to see if the treatment is effective. To treat this problem, it’s recommended using insecticidal soap or insecticidal oil. Both petroleum-based horticultural oils and plant-based oils such as neem, canola or cottonseed oils are also acceptable. Be sure to read the manufacturer’s label first and use proper IPM principles.
by Nancy Denison, Advanced Extension Master Gardener
I acquired Volumes 1 & 2 of 10,000 Garden Questions Answered by 20 Experts, edited by Marjorie Dietz, from my mother-in-law. She was cleaning out her four very large bookcases in preparation for moving west more than 10 years ago. I look at them every once in a while, but then I close them up just as fast. With each volume containing over 700 pages AND 10,000 questions, it was a bit mind boggling to even begin to search for an answer to anything.
So, with winter slowly moving along, I thought I’d dive in to see what I might find. This set was first published in 1944 by Doubleday, with new editions in 1959 and 1974, and was an American Garden Guild Book. There are 10 garden experts, such as Bebe Miles, Helen Van Pelt Wilson and Donald Wyman, listed as contributors, with many more listed as advisors, editors or artists.
In the Introduction to the third edition, Marjorie Dietz called it the “family bible” of garden information. The questions are divided into 16 general areas from “Soils and Fertilizers” to “Roses and Houseplants” to “Regional Gardening Problems.” In this edition, botanical names were updated to conform to the International Code for the Nomenclature of Cultivated Plants. Under the first editor, F.F. Rockwell, these books were first begun in response to many requests from readers of The Home Garden Magazine. It was hoped to give the home gardener practical information for personal gardening issues.
There is a small section on how the books are put together and how best to use them most effectively. Each of the sections begins with basic information about that subject and then how to utilize the index for more specificity. I find the sheer amount of questions a bit distracting. For example, in the “Soils and Fertilizers” section there are questions about soil problems…eroded soil, depleted soil, neglected soil, poor soil… and on and on. So, the questions and answers do cover just about everything on each particular topic. Beneficial in some ways, annoying in others.
Topics covered in Vol. 1 include “Planning and Landscaping,” “Tree and Shrub Selection,” “Design Principles,” “Herb Gardens” and more. Vol. 2 continues with the “Home Vegetable Garden,” “House Plants,” “Weeds,” and “Regional Garden Problems,” with “Sources for Further Information” concluding the book.
I had hoped, a little, that the books might be of value. But alas, on Amazon they could be found for $6 and under, except for a couple of listings for much more. I guess I’ll just be happy with the sentimental value and the “historical” perspective of gardening they present.