Roots, Shoots, Fruits & Flowers: Crawfish Chimneys, Growing Avocados, & Azalea Dieback

A typical Louisiana crawfish chimney. Photo: LSU AgCenter.

Louisiana crawfish chimney

After all the rain this past spring, Vivian asks, “I have a question. Is the soil that crawfish chimneys are made of good to add to potting soil and use as soil for a large box planter? For vegetables to be grown in.”

Dr. Kiki Fontenot, the AgCenter’s vegetable specialist, responded to Vivian questions positively, “The crawfish chimney soil would probably be fine to add to large pots you are growing vegetables in. I probably would not use this soil to start seeds in. For example, if you plant on refilling a six pack or smaller containers to start your seeds, I would use fresh potting soil. My reasons are because the soil in the ground (crawfish chimney soil) has the potential for having bad bacteria and fungus in it, that would be harmful to seeds. Also, it probably has more clay in it, thus standing up like a chimney. Clay tends to crust over when wet and can form a hard layer that is not easy for seedling to penetrate. So, stick with potting soil for starting your seeds, but if you knock a few chimneys over, I see no problem adding that soil to large pots or to your garden or raised beds.”

420_fig_2_avocado_tree_in_potjpgjpgAn avocado in a pot.
Photo: LSU AgCenter

Avocado in a pot

David from Jena wants to help his wife with a gardening idea, “My wife sprouted some avocado hearts and subsequently potted them. Do these things have a chance of surviving and being productive in central LaSalle Parish? Anything special needed for them to survive the winter?”

Avocado is like citrus and will need protection from freezing temperatures. One practice that enables gardeners to grow citrus outside of its southern range is to plant on the south side of a building. The building offers protection from northern winds, and it probably radiates stored heat during the night.

Also, gardeners will use heat lights, flood lights, coverings and other creative ideas for protecting their citrus. These practices will help your wife to grow her avocado.

Also, there is a new fungal disease in Louisiana called laurel wilt (LW) and it is spread by the red bay ambrosia beetles (RBAB). Avocados, bay trees and sassafras trees are susceptible to LW. So far there is no treatment available. If you see your sassafras tree dying, then it is probably an LW infection so please report this complaint to your local Extension agent.

Finally, Dr. Joe Willis, an Area Horticulture Agent, wrote a detailed article entitled, “Growing Avocados”, with detailed information about growing avocados. Go to and search for “Growing Avocados” to read more about the culture of the “alligator pear” or avocado.

420_fig_3_Azalea_diebackjpegAzalea with dying branches. Photo: Tyler Geymann.

Azalea dieback

Tyler sent an email with several questions, and here are a couple of them, “Would you consider a sycamore planted 25’ from a house to be a potential problem tree? Your water oak article brought up the question, as it is also a fast-growing tree.

And lastly, I’m attaching a couple photos of azalea die back. Could you speculate what might be causing this problem?”

Tyler later shared that his sycamores are recently planted trees. The answer to Tyler’s question about hazard trees is that his sycamores are unlikely to be a potential hazard for many years. Because the American sycamore is a more substantial tree than the water oak, Tyler can enjoy his trees for a long time.

Dan Gill, retired AgCenter horticulturist, addressed this specific topic in one of his articles, “Dieback is a disease of azaleas caused by the fungus Phomopsis. Typically, dying branches (stem dieback) begin to appear on an otherwise healthy plant. The leaves die and remain attached to the plant. Usually a single branch or a few branches on an established plant are affected. Scraping away the bark with a knife reveals discolored wood under the bark that appears chocolate brown.

Dieback is difficult to control on azaleas in the landscape. Reduce stress to the plants by planting in partial shade and watering during dry periods. Drought stress and freeze injury may predispose azaleas to infection. Make sure you water the planting deeply once a week during hot, dry summer weather. Keep the bed mulched. It rarely gets cold enough in Louisiana to bother azaleas, particularly in the southern part of the state.

Prune infected branches well below all discolored wood and dispose of dead plant material. Clean pruning tools between cuts with a diluted solution of household bleach (1-part bleach to 9 parts water) or 70% rubbing alcohol. Fungicide sprays containing either thiophanate-methyl or mancozeb can be used after pruning to reduce the chance of additional symptoms.”

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.

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

4/16/2020 3:45:50 PM
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