It happens every year. By the end of July, my zucchini plants have bit the dust. I know of some gardeners who do not like to grow zucchini because they find themselves overwhelmed by the plant’s productivity. But that is not a problem I face because of two little “friends” who call my garden home – Erwinia tracheiphila (a bacterium) and the cucumber beetle.
It is clear that the cucumber beetles in my garden have an E. tracheiphila infestation. This bacterium lives in the digestive tract of some cucumber beetles. When the infected beetles nibble on the leaves of my zucchini, they leave behind droppings swarming with this bacterium. The bacteria get into the plant, multiply, clog up the xylem (the plant tissue that carries water from the roots to the stems and leaves) and the next thing you know, the zucchini plants are wilted and their stems are a soft, stinky mess! (The other major cause of wilting in zucchini is the squash stem bore. This wasp-like insect lays eggs at the base of the plant and the larvae bore into the stem and cause the plant to wilt. A close examination of the stem will show a small pile of green or yellow sawdust like material. Thankfully, squash stem bores do not appear to have made my garden their home!)
Knowing the biology and pathology of what is happening does help to explain the problem and make sense of it, but I miss my zucchini. Over the years I have tried all kinds of things: different mulches, pesticides (in my pre-organic days), garlic spray, floating row covers and interplanting the squash with onions. Nothing has really worked. One web site recommends commercial growers with a wilt problem to not growing cucurbits (squash, pumpkins, cucumbers and melons) for six years to break the insect/disease cycle!
That probably would be the best thing to do. I have learned that once my zucchini die, the cucumbers will soon be doing the same. And I cannot grow winter squash at all because the fruit does not mature before the wilt takes over.
But I am not sure that I am ready to give up on zucchini. I think there are some other options. I could just accept the fact that zucchini is a short-lived vegetable in my garden and plant a new hill every few weeks until mid-July, knowing that as one planting dies, a new one will be coming into maturity. I have read about the organic use of kaolin clay (Surround WP) as a foliar spray that renders the plants unrecognizable to cucumber beetles. That sounds interesting. Another idea is to try growing some zucchini in a large pot or whiskey barrel far away from the vegetable garden. If I use artificial soil there will not be any beetle larvae or eggs in it and it will probably take some time for the cucumber beetles in the garden to find this lone, isolated plant. I have grown zucchini in a barrel before and it grew very well.
Dealing with problems like this can be frustrating but it is part of what I love about gardening. Sure it would be nice if everything grew perfectly with no insects or diseases but I know that is unlikely to happen. Instead of cursing the insects and diseases, I can face these setbacks and enjoy learning the biology of them. I can experiment with new tricks and techniques to control and/or manage the problem. If I cannot control the disease or insect, I can learn to live with it and work around it. And if nothing works, there are a lot of farmer’s markets around that will gladly sell me zucchini from their fields that do not have an E. tracheiphila infected cucumber beetle problem!
So, rest in peace zucchini. You fought the good fight and produced a number of fruit for my enjoyment. I now have ten months to think about how I can keep you alive next year. After all, I think that is the gardener’s motto – next year...!
About the Author
Michael C. Podlesny is the owner and a contributing writer for Mike the Gardener Enterprises, LLC the exclusive home for the Seeds of the Month Club.
I feel your pain, I too have this problem. I've resorted to planting prodigious amounts of cucumbers at intervals in all corners of my garden, hoping that somehow one will survive when the bacterium takes hold. So far, the beetles are more interested in the cucumbers and beetles - so I'll keep my fingers crossed for my zucchini (round two - borers got the first batch). As for not planting cucurbits for several years - I think that would be fruitless and disappointing advice to follow - both beetles and bacterium appeared in my garden the very first year I started and cucurbits had never been planted there before that.
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