Monday, May 4, 2009

Pest Control: Cucumber Pickleworms

Planting time is a good time to think about pest control, so I looked up the UGA fact-sheet on growing cucumbers and found a warning about cucumber beetles—keep them under control (through unspecified means) because they spread disease. That could be a useful warning, but I am pretty sure I have never had a problem with cucumber beetles. My pest problem in cucumbers is cucumber pickleworms .

Last year, the cucumber pickleworms had a very good year, and my cucumbers had a correspondingly bad year. Almost all of my cucumbers had the little shot-holes that show where a larva has eaten its way into the fruit. The little pests were also worse than usual at the Plant a Row for the Hungry garden where I volunteer, so I know the problem was not just in my yard.

I have a copy of The Organic Gardener’s Handbook of Natural Insect and Disease Control , and when I realized the cucumber harvest was in serious jeopardy I checked the pickleworm section for advice. One suggestion was to plant a “trap crop” of yellow squash, since the pickleworm likes those even better than it likes cucumbers. The other advice was to plant early maturing varieties of cucumbers so that a good harvest could be brought in before the pickleworms totally demolished the crop.

This advice might have been useful a couple of months earlier (at planting time!), but it didn’t help much at the time. However, spring has come around again, and I have another chance. I am not changing my cucumber varieties, though, because they already are varieties that mature fairly early, and I don’t really have the space for trap-crops, other than the zucchini that usually keels over before the onslaught of the pickleworm, so I am hoping for a different solution.

The Pickleworm Management page from North Carolina State University, recommends the use of Sevin (carbaryl) to manage pickleworms. People who are averse to using pesticides (even this one which is a relatively safe chemical for home gardeners to use), are going to hope for another option.

According to the fact sheet Cucumber, Squash, Melon & Other Cucurbit Insect Pests from Clemson University, pickleworms don’t survive winter freezing, and the adults fly up from Florida each year:

“In South Carolina, pickleworms starve or freeze to death during the winter. They overwinter in Florida and spread northward each spring. Severe damage usually does not occur before summer in South Carolina. Heavy populations generally do not build up before the first flower buds open; however, late crops may be destroyed before blossoming.”

It seems reasonable that when the Southeast has an early or unusually warm spring, or early, strong winds heading north out of Florida, the pickleworm damage might start earlier than usual, like it did last year.

A couple of those linked resources also mention that the parent of the pickleworm is a night-flying moth. This seems like information that could be used to thwart those pickleworms. I am thinking about covering some of my plants at night, to keep the moths from laying eggs on my plants, then uncovering the plants in the morning, so bees and other pollinators can get to the flowers.

This sounds like work, I know, and some of my cucumbers will be trellised and a serious hassle to cover up each night. So, I will leave the trellised vines uncovered and only cover the pickling cucumbers that will be sprawling on the ground this year. This way I will have both an experimental plot--covered-- and a control plot--uncovered-- (ignoring that they are different kinds of cucumbers), so the experiment may be able to tell me whether the nighttime covering makes a difference in pickleworm infestation.

I’ll let you know how the experiment turns out.


  1. How did the covering of the cucumbers go?

  2. I had trouble remembering to cover and uncover the cucumbers, even though they were right outside the front door. Ironically, 2009 turned out to be a good year for cucumbers--the pickleworms didn't show up until very late. This (2010) is the year I should have covered the vines! Live and learn...


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