|A December cold front with overnight lows in the 20s has blasted these English Marigold (Calendula officinalis) blooms, but the real peril here are the leafhoppers that are far too small to see in this picture.|
And then, as they say in the U.K., it all went pear-shaped.
(Love the expression, but more prosaically, let's just say that I felt the experiment had run its course and was not a roaring success.)
What went wrong?
In a word: Leafhoppers!
In two words: Leafhoppers, argh!
I tend not to spray pesticides in the garden. Mostly I adhere to a survival of the fittest rule and if a plant can't take care of itself, I'm not going to coddle it along.
Well, I had forgotten just how susceptible the English marigolds are to leafhoppers. These insects are not terribly obvious until you brush against a plant and a little cloud of light green insects goes hopping off onto neighboring plants, only to quickly jump back to the Marigolds when your back is turned.
Leafhoppers suck the sap of vascular plants. In other words, they'll gradually weaken and then kill the host plant as their numbers increase. According to the Illinois Natural History Survey (INHS), leafhoppers do have many natural predators, but those predators do not seem able to keep the leafhoppers under control in my garden on this particular English Marigold crop. In fact, I now remember how I had to pull most of the English Marigold crop in mid-summer due to a leafhopper infestation (plus the fact that the Marigolds were baking in the heat and humidity of July and August).
I believe that English Marigolds must be particularly susceptible to leafhopper infestations, because I cannot recall having problems with them on any other plants this past year, except for the zinnias, which only became infested as they were already declining and reaching the end of their life cycle.
Now part of me, wanting to be a super eco-friendly gardener, supposes that it might be best to leave the English Marigolds. After all, the Marigolds do attract some bees and presumably the predatory wasps, spiders and birds that INHS says feed on leafhoppers would prefer to have a robust prey population.
Well, that may be the case, but I've never seen any birds browsing the marigolds for leafhoppers. Perhaps there are different birds that eat different leafhoppers elsewhere, since INHS says there are an estimated 100,000 species of leafhoppers around the world.
And besides, one major problem is that I don't want to provide an environment for the leafhoppers to breed and flourish. While my gardenia or my camellias for instance may not naturally support loads of leafhoppers, when the Marigolds foster massive populations, I think some of the little critters hop onto other nearby plants and do some damage there.
In any case, once the leafhopper population builds sufficiently on the Marigolds, many of the younger Calendula plants are overwhelmed early in their lifecycle, staying stunted and small, growing yellow and dying before they can flower, which sort of defeats the purpose of growing them as a cover crop.
So, gardening is a learning process and I'm certainly not above admitting my mistakes. (Mea culpa!) Even this late in 2012 I'm still learning and still making mistakes! And that's why at this point, I disavow the post I made just a week ago singing the praises of English Marigolds and revert to my earlier position that English Marigolds are more trouble than they are worth.
Now French Marigolds on the other hand, I endorse without reservations! :) (But obviously I've been wrong before and may some day have to eat my words on this recommendation too!)
PS - What would you have done? Would you have sprayed? Pulled the plants like I did? Let events run their natural course?
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