Roots, Shoots, Fruits & Flowers: Plants Diseases in the Landscape and in the Vegetable Garden

513_fig_1_dying_bayjpegA bay laurel intended for seasoning for food shows wilt symptoms. Photo: Tammy Cecil, Master Gardener.

Fungal disease in bay and sassafras trees

In May, a couple of homeowners, who live parishes apart, shared very similar complaints. Tammy, from Anacoco, wrote this note, “I read with interest the recent questions [about laurel wilt] in [a local newspaper], and I believe I'm losing a bay tree to [laurel] wilt. We lost 2 sassafras trees over the last year on the family land, but we already cut down and burned those trees.”

Robert, of Reeves, LA, shared a similar concern, “All my sassafras trees are dying. Not just the leaves but the branches too. I mean all of them.”

For both cases, the symptoms point to laurel wilt (LW), a fungal disease spread by the red bay ambrosia beetle (RBAB). Native trees like sassafras and bay are susceptible to LW. If any gardeners are trying to grow avocados, their plants are also at risk of infection. Currently, there is no treatment for either the disease or for the insect.


A native sassafras tree with both wilted and dead leaves. Photo: Robert Johnson.

513_fig_3_wilting_peppersjpgOne of two pepper plants with wilt symptoms. Photo: Ethel Smith, Master Gardener.

Pepper plants are wilting

Ethel of Jena also is complaining about wilt in her garden pepper plants, “[Do you have] any idea of what’s wrong with these two bell pepper plants? My other three look fine.”

There are two wilt diseases able to attack peppers. One possible disease is southern bacterial wilt (SBW), a fungal soil-borne disease. Dr. Don Ferrin, a plant disease specialist, wrote in an AgCenter factsheet on how to manage SBW, “Recommendations for the management of southern bacterial wilt include avoid planting susceptible crops in infested fields, avoid late plantings of tomatoes in areas know to be infested and use of long-term rotations with non-host crops (such as corn, beans and cabbage).”

The other disease may be tomato spotted virus wilt (TSVW), a viral disease spread by insects. An article on the AgCenter website makes these points:

  1. “Spotted wilt is difficult to control. Unfortunately, there is nothing to do but pull the plant once the plant becomes infected.”
  2. “The easiest way to prevent this virus is to grow TSWV-resistant cultivars.”
    1. “Resistant beefsteak tomato cultivars in the Southeast are BHN 640, Amelia, Bella Rosa (hot set), Crista, Mountain Glory, Quincy and Talladega (hot set).”
    2. “Resistant Roma types are BHN 685, Muriel and Picus.”


Bean seedling with damping off disease. Photo: Darlene Ray, Master Gardener.

"Damping off" fungal disease

Darlene is also complaining about her ailing vegetable seedlings, “These peas and beans came up looking good. We had some hail damage a couple weeks ago. Now, leaves are turning brown on many plants and they are curling up. We dug a plant and there is not a good root growing. Please advise if this is just a loss or if anything can be done.”

First, Darlene examined the roots of her plants, and it is a good idea to examine roots of dead or dying plants because sometimes the condition of the roots can help with diagnosis. Gently dig up a plant to avoid pulling up it up. Pulling a plant up may leave some diagnostic tissue in the ground and make diagnosis more difficult.

Darlene probably has “damping off disease”. This fungal disease takes advantage of cool, damp soil conditions. Dr. Raj Singh, a Plant Pathologist with the AgCenter, makes these recommendations, “Good cultural practices — including proper soil preparation, use of raised beds to provide adequate water drainage, proper planting depth and plant spacing, and planting in fertile soils with proper soil pH — play key roles in growing healthy seedlings.

‘Avoid sowing seeds or transplanting seedlings in cool, wet soils,’ Singh said. ‘Overwatering before or during the germination process may adversely affect seedling stand.’

Using fungicide-treated seeds or transplants also may be beneficial, he said.”

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.”

5/13/2020 4:27:09 PM
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