Roots, Shoots, Fruits & Flowers: Louisiana Irises, Mosquito Dunks & Opium Lettuce


Louisiana iris. Photo: Dan Gill, LSU AgCenter.

Louisiana Irises

Lori is a fan of bearded irises and sent this message, “My husband and I are both native Louisianians but only recently moved back to Baton Rouge after nearly 30 years. That said, we are rediscovering Louisiana gardening and slowly cleaning up the existing plantings, building new beds and raised gardens. We would love to receive the… [RSFF] blog. I have one question for you . . . At our last home in Idaho, we had some beautiful, bearded iris and are thinking of planting some here too along with Louisiana iris. I know the Louisiana iris foliage remains green year-round. How do bearded iris compare? Are they dormant here also?”

Dan Gill, retired AgCenter horticulturist, writes this narrative about the Louisiana iris and its flower, “Blooming from late March to early May, the Louisiana iris is a floral ambassador that has carried our state’s name all over the world.”

Gill also share this point about establishing this iris,” The best time to plant Louisiana irises is in August and September when they are dormant, but you can buy and plant them in spring while they are in bloom with good success as well. When purchased and planted in spring, however, Louisiana irises need to be handled carefully to avoid damaging the foliage and flower buds, and you may need to stake the plants after planting to hold them upright after planting (established Louisiana irises do not need staking).”

Finally, the Society for Louisiana Irises (SLI) reports that the five species of Louisiana irises belong to a group of beardless irises called Apogon. The website for SLI is: .


Mosquito Dunks™ are a safe, organic treatment for mosquitos. Image: Home Depot™.

Mosquito Dunks

A homeowner with plenty of standing water after heavy rains complained about mosquitos and was looking for something to spray. Spraying may be difficult, but another possible treatment would be Mosquito Dunks™ (MD). Mosquito Dunks™ are an organic larvicide, and it prevents mosquito larva from reaching the adult stage. The active ingredient in MD is a pathogen, Bacillus thuringiensis subspecies ‘Israelensis’ or BTI. BTI is a bacterium that is deadly to mosquito larvae but harmless to other living things.

A single MD are shaped like a doughnut and is placed in standing water. MD will float until it completely dissolves. Dr. Kristen Healy, Insect Specialist with the LSU AgCenter, tested this product on honeybees, and MD had no toxic effects on honeybees. Really, she was trying to kill bees with MD and could not. MD is also safe for people and pets.

A single MD can treat 100 square feet regardless of depth of water, and a treatment lasts 30 days. Mosquito Dunks are available online and at retail stores.


Wild, or opium, lettuce. Image: NC Extension.

Opium Lettuce

John D. from Dry Creek asked AHA about “opium lettuce” and possible benefits. Opium lettuce also goes by the name of wild lettuce, and its botanical name is Lactuca virosa. Botanists from Europe report that wild lettuce is native to Great Britain and central and southern Europe. Flora of North America have documented this plant in California, Alabama, Iowa and Washington, DC.

According to WebMD website, Wild lettuce is used for whooping cough, asthma, urinary tract problems, cough, trouble sleeping (insomnia), restlessness, excitability in children, painful menstrual periods, excessive sex drive in women (nymphomania), muscular or joint pains, poor circulation, swollen genitals in men (priapism), and as an opium substitute in cough preparations.

Also, WebMD reports these “Special Precautions & Warnings”:

  • Pregnancy and breast-feeding: Not enough are known about the use of wild lettuce during pregnancy and breast-feeding. Stay on the safe side and avoid use.
  • Enlarged prostate (benign prostatic hyperplasia, BPH): Do not use wild lettuce if you have this condition. It contains a chemical that can harm people who have trouble urinating.
  • Allergy to ragweed and related plants: Wild lettuce may cause an allergic reaction in people who are sensitive to the Asteraceae/Compositae family. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many others. If you have allergies, be sure to check with your healthcare provider before taking wild lettuce.
  • Narrow-angle glaucoma: Do not use wild lettuce if you have this eye condition. It contains a chemical that might make glaucoma worse.
  • Surgery: Wild lettuce can affect the central nervous system. There is a concern that it might cause too much sleepiness if it is taken along with anesthesia and other nerve-numbing medications used during and after surgery. Stop using wild lettuce at least 2 weeks before a scheduled surgery.

On balance, the use of wild lettuce seems risky, and its use should be avoided until more information about its safe use is published.

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 Also, you can be on the “green thumbs” email list by emailing your request to the address above.

“Before you buy or use an insecticide product, first read the label, and strictly follow label recommendations. Mention of trade names or commercial products in this article is for informational purposes only and does not constitute endorsement by Louisiana State University AgCenter.”

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

2/25/2021 2:06:23 PM
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