Roots, Shoots, Fruits & Flowers: Cow Ant, Banded Cucumber Beetle, and Downy Mildew

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A cow ant. Photo: Darrell Powers.

Cow ant

Clayton shared an essay admiring an unusual insect, the “cow ant”. He wrote, “Consider the cow ant.

A few days ago, a half grown one was in my garage. Now, the cow ant is number 10 on my top ten list of “noble insects”, which I don’t kill or bother: rhino beetle, 1; Praying mantis, 2; the large dragon fly, 3; so on and so forth.

We had cow ants in Florida, but [they] were rarely seen. I maybe saw a handful in the nine years I was there. Not common, but not uncommon here [in Louisiana, but] I see one or two a year right in my back yard.

I was watching a show on strange North American animals, and the cow ant was profiled. [It was] supposed to have a very painful bite. Well, it turns out the cow ant is not an ant at all. It is a wasp! [It] belongs to a family of wingless wasps. Who knew? Not I!!! Bite [hades], it has a [heck] of a sting. Even so, I will leave them alone…unless while wearing slippers in the yard and get stung. That [sting] may change my view.”

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A banded cucumber beetle (BCB). Photo: Melissa Becker, Master Gardener.

Banded Cucumber Beetle

Melissa, a Master Gardener, sent her email and picture, “Is this a banded cucumber beetle? They are on my daughter’s tomatoes and peppers in grant parish.

Melissa wanted to confirm her identification of the banded cucumber beetle (BCB), and she was correct. According to the LSU AgCenter, the cucumber beetle is a pest of sweet potatoes because their larvae are rootworms and feed on the tubers to cause blemishes. For commercial growers, these blemishes reduce the value of the crop. These beetles can damage corn, bean, squash, and other vegetables.

Texas Agrilife Extension share this information, “In addition to the plant damage caused by their feeding, the beetles carry viruses and bacterial wilt. Larval form known as Southern Corn Rootworm.”

Mississippi State University Extension recommends this control treatment, “Control adult cucumber beetles in home vegetable gardens with sprays containing permethrin, bifenthrin, or carbaryl. Check young plants and emerging seedlings regularly and spray promptly if necessary. Older plants can tolerate higher numbers of beetles. Before spraying edible plants with any pesticide, always be sure to note the pre-harvest interval for the product you are using and the crop you are using it on.”

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A squash leaf with downy mildew, possibly. Photo: Rose Schmidt, Country Gardens.

Downy Mildew

Rose sent this message and email on behalf of a client, “I had a customer call me this morning asking about a problem she is having with her squash. The plant is growing great and it is putting on lots of blooms.

But the blooms either fall off or the ones that are putting squash on, the squash gets about 2-3” long and then drops off. What may be the problem?”

Dr. Raj Singh, the “plant doctor” with the LSU AgCenter sent his assessment of this condition, “The angular leaf spots and leaf necrosis (dead tissue) is most probably caused by downy mildew.”

Dr. Don Ferrin, disease specialist, wrote in an AgCenter publication, Downy Mildew of Cucurbits, “Disease control relies primarily on the use of fungicides since resistant varieties are available only for cucumbers and some melons (but not watermelons). Fungicides are most effective when they are applied before the onset of disease, and they must be applied repeatedly if environmental conditions are suitable for disease development. Because this pathogen can develop resistance to fungicides quite readily, it is important to follow label instructions regarding their use.”

If you want to contact Roots, Shoots, Fruits and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337-463-7006 or khawkins@agcenter.lsu.edu. Also, you can be on the “green thumbs” email list by emailing your request to the address above.

“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”

5/26/2020 8:34:08 PM
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