Roots, Shoots, Fruits & Flowers: Southern Blight, Blue Wildflower, Robber Fly & Barklice


A tomato plant with Southern Blight, a fungal disease. Photo: Peggy Kessler, Master Gardener, Grant Parish.

Southern Blight

Peggy, a Master Gardener in Grant Parish, sent an email with a clear picture and asked, “This [disease] appeared on a friend's tomato plant and pepper plant right above soil line [and it] killed both plants. [Do you have] any ideas or suggestions?”

Peggy’s friend has a soil-borne, fungal disease call Southern Blight. The AgCenter has a factsheet titled, “Southern Blight,” and it is a free, downloadable document. This publication provides a few treatments to manage this disease:

  • Soil solarization –Cover and secure clear polyethylene plastic over moistened soil.
  • Deep plowing – Turning the soil before planting can reduce the amount of [fungal growth], in the upper soil layers and slow disease development. Soil depths of three inches are required to prevent [fungal] germination.
  • Soil amendments – Liming the soil to raise the pH or using calcium nitrate or other non-acidifying types of fertilizer will slow the germination of…fungal growth.
  • Plastic mulch – Plastic mulches can help to reduce disease by forming a physical barrier between the plant or fruit and the pathogen. For small plots, the same effect can be achieved by wrapping the lower 2-3 inches of the stem with aluminum foil from the soil line upward.
  • Fungicides for Southern blight control are not available for homeowners to purchase at retail centers.


Ovate false fiddleleaf, a native wetland plant. Photo: Larry Allain, USGS.

Blue Wildflower

Judy, a Master Gardener from Jena, shared an email with an image of a blue wildflower and a question, “Could you by any chance ID this weed? I have used several plant IDs and cannot find it. My son-in-law discovered it around a pond on his property. You cannot see it in the picture, but it also has small thorns.”

Judy’s wildflower is an ovate false fiddleleaf or hairy hydrolea, a native wetland plant in Arkansas, Louisiana, Mississippi, and Texas. The US Geological Survey shares a note about this plant, “The Prairie Acadians boiled the long roots of this plant with sugar to make cough medicine. Bumble bees and hawk moths are frequent visitors to its flowers.”


A robber fly or assassin fly, a beneficial insect. Photo: Pam Archer, DeRidder, LA

Robber Fly

Pam in DeRidder share an image and asked, “Can you ID this bug for me? Several [of them ] have come in the house lately. Do they bite or sting?”

This fierce-looking insect has a couple of violent names: robbery fly or assassin fly. Despite its appearance and name, it is a beneficial insect because it is a predator of insects. If it is mishandled, it can inflict a painful bite.


A tree covering webbing by barklice. Photo: LSU AgCenter


Violet, a landscape professional, sent a video of a tree with webbing and asked, “A friend of ours noticed this limb looked different in this tree. She says it looks like spider web! Should they be concerned?”

Junior Batty, a retired Extension Agent, wrote a blog about webbing on trees in 2012, “Barklice are small, most often wingless, soft bodied insects that are in the Psocoptera insect order. Although they resemble aphids and are called ‘lice,’ neither the webbing nor the insects cause any damage. The webbing is produced by the insect as protection from predators. The webbing typically covers only the bark on trees, the main trunk, branches, and the ground area of the roots. No leaves will be covered due to the barklice.

The insect feeds on decaying bark, algae, and lichen. The cob web materials usually appear in late August to early September. This year however the “ghostly” look has come early due to our early spring and lengthy periods of high humidity

The barklice and its webbing cause no harm, and no control is necessary. If webbing is a concern just brush it off with a broom or use a high-pressure stream of water. The insect is really ‘more bark, than bite.’”

If you want to contact Roots, Shoots, Fruits, and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337.284.5188 or or .

“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.”

6/28/2022 9:19:41 PM
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