by Mort Mather

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The Organic Gardener's Handbook of Natural Insect and Disease ControlFor Christmas I received two similar garden books—The Organic Gardener's Handbook of Natural Insect and Disease Control and Rodale's successful Organic Gardening Controlling Pests and Diseases (both Rodale Press, Emmaus, PA). Sometime last summer I mentioned that I needed a good book on disease identification. Barbara remembered.

In the realm of insect and disease identification there are two important things to look for. First, is it easy to find the problem you are trying it identify? To do that you should be able to look up the plant on which you found the problem and that should lead quickly to the problem. It is like translating from one language to another. We know the names of our plants—can translate the physical plant that we are looking at in the garden to a word. We then take that word and, with words, identify the condition we find on the plant, its possible causes, and then find pictures of the possible causes which we can then relate back to our own plants. The Handbook does that well.

Sometimes we don't need a translation—we see an insect or condition and we want to find that insect or condition and learn about it. The Controlling book is organized best for this type of search and the pictures are excellent.

In my case last summer my potato plants died an early death leaving me with small potatoes. My problem looked to me like a disease. The leaves turned brown and curled. Since I thought it was a disease and I had no books on plant disease I just talked about it with other gardeners. In conversation I learned that leafhoppers had invaded the state on warm winds from the south and they were the cause of the trouble. Without questioning further I assumed that the leafhoppers had brought some disease with them that had killed the plants.

Assumptions are always dangerous. They are a major factor in causing wars, the most frequent root of marital discord and, in general, the underlying reason for misunderstandings and disputes. In this case my assumption kept me from learning the truth when information was available.

First, I assumed that a brown leaf-hopping insect that I have seen in the garden numerous times was a leafhopper. I have never identified this insect as it does no apparent harm. The potato leafhopper is 1/8 inch long (barely visible) and bright yellow-green. I don't think I ever saw one. If I had looked up leafhoppers in my favorite insect identification book, The Gardener's Bug Book by Cynthia Westcott, I could have gone back to the potato patch and tried to see the critter.

Second, I assumed the browning of the leaves was due to disease brought by the insect. Wrong again, maybe. Leafhoppers not only suck juices from the leaves, their toxic saliva causes leaves to turn brown and curl which is called "hopper burn" or "tip burn". Maybe hopper burn was my problem but it could also have been a disease. Again, I can't go back to the plants to try and figure it out.

I will have no excuse for making wrong assumptions on plant disease in the future now that my library on the subject is comprehensive. Next week, unless I am distracted by a world issue, I'll answer a readers question on how to control leafhoppers.

©December 29, 1997

Mort is a husband and father. He authored a book, Gardening For Independence and was named Environmentalist of the Year by Down East Magazine in 1987. He is a consultant for organizations. His address is 802 Bald Hill Road, Wells, ME 04090.


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