Dr. Raj Singh, the Plant Doctor, at Plant Diagnostic Lab. Photo: Olivia McClure, LSU AgCenter

Soil Pathogens

Ranelle of Leesville, LA reached out to the LSU AgCenter with this question, “I have a small garden and need to see if the soil has bacterial wilt. Do you test soil samples for that? Thank you.” There are two types of soil testing. The most well-known test is for fertility by the Soil Testing & Plant Analysis Lab. Both farmers and gardeners use this lab frequently for recommendations about liming and fertilizing their fields and gardens. The other type of soil testing is for diagnosing soil-borne plant disease, and it occurs at the Plant Diagnostic Lab (PDL). Dr. Raj Singh, the AgCenter’s Plant Doctor, supervises this lab and directly participates in making diagnoses. Here is a link to contact the Plant Diagnostic Center.

Bracket fungi on a pecan tree. Photo: Mara Trotter, homeowner.

Bracket Fungi

Mara is a regular contributor to RSFF with respect to questions. She asked about fungi growing in her landscape, “I have two pecan [trees] in the backyard--this is the 2nd one. It is still alive, but [it] has lost several large limbs. The fungi that were growing on the… dead one, was edible (but I did not eat). This stuff [ in this picture] is hard, I would not dream of eating it, either. The amazing thing to me is--how do the fungi spores find the tree to start growing?! ”This first task at hand is identifying the fungus on her tree. She has a bracket fungus, a group of fungi that decomposes woody material. The fungi shown above is also native to Louisiana, and it decays woods and adds organic matter to soil. If there are conks on live trees, then there is decay inside of the trunk. In heavy wind conditions, a tree with this fungal infection may fail and cause damage to property. Sometimes these fungi will go from rubbery to hard in dry conditions.

Secondly, avoid eating any fungus unless a skilled mushroom expert has correctly identified the fungus and knows that it is safe to eat. Finally, these fungi produce millions of spores that are transported by wind. These spores are opportunistic and will infect a tree wound.

Raised bed and container garden. Photo: Mark Carriere, LSU AgCenter.

Raised Beds

Tom is helping a friend and wants to “to get recommendations on how to improve drainage in that soil. It is too heavy to support growth when it is rainy.” The most cost-effective way to improve garden drainage is to use raised beds, and the LSU AgCenter has a factsheet, “Home Garden Series: Raised Beds.” This publication is a fee-free, downloadable document for a gardener’s reference notebook. This factsheet covers the entire process of starting, designing, constructing, and using raised garden beds. There is also a narrative on creating a handicap accessible bed or a “salad table.”

Quince rust, a fungal disease on mayhaw fruit. Photo: Dick Rohlfs, DeRidder, LA

Quince Rust

Dickie has a home orchard and sent this message, “I was wondering if you or someone at the LSU AgCenter could know what is causing some of my mayhaw berries to develop this problem. I am not sure what I need to do to prevent this. Any help would be appreciated.”

These mayhaws are suffering from quince rust, and applications of fungicides will prevent infections. Another contributing factor is the presence of redcedar trees. Quince rust will infect a cedar tree, then a mayhaw, then a cedar tree and so on. Mayhaws and cedars are called alternative hosts because quince rust needs both plants for its life cycle.

The good news for gardeners is the wide variety of fungicides available at garden centers. These fungicides are labeled for a wide variety of fruits, vegetables and ornamentals and are labeled for a wide variety of fungal diseases. As always, read the label of your fungicide for safe and effective use.

Cranberry fruit worm on blueberry. Photo: Jerry Payne, USDA/ARS.

Cranberry Fruitworms

Todd, an Auburn fan, has a fruit question, too, “I am hoping you can advise me on how to treat CRANBERRY FRUIT WORM[CFW]. We have ten 3- to 4-foot-tall blueberry bushes to treat. Thank you! WAR EAGLE!!!!!!!!!!!!!!!!”Dr. Denisa Attaway wrote a narrative about treating for CFW for the AgCenter:

• Cultural Control: Elimination of weeds and trash around plants helps by cutting down on overwintering protection for fruitworm cocoons.
• Mechanical Control: Cranberry fruitworm was effectively controlled in the past by picking off infested berries, which are easily detected because of the webbing and their early ripening. This method is still practical in small plantings with light infestations.
• Insecticide Control: Clean cultivation will reduce the population of cranberry fruitworm within a field significantly, but insecticide treatments may still be needed to achieve satisfactory control of this pest. The Pest Management Guide for insect pest includes this insecticides:
  • Malathion® 57EC
  • Carbaryl® 50 W (Sevin®)
  • Spin Tor® 2SC