Roots, Shoots, Fruits & Flowers: Lichens Again, Bacterial Leaf Scorch, Birdfeeder Habits & Ailing Muscadine Vine


Two types of lichens on a plum branch.
Photo: Ashley Midkiff, LSU AgCenter.

Lichens Again

Mr. Darrian from Vernon Parish brought in some growth samples from his yard trees to identify. Mr. Darrian has harmless lichens on his trees. The stringy lichens on the left of the photo are called “fruticose” lichens, but AHA calls them “reindeer” lichens because they resemble antlers. The flat, leafy lichens on the right side are called “foliose” or leafy lichens.

Homeowners are often concerned when they see lichens. However, Dr. Raj Singh, a plant pathologist, wrote this line in the “Lichens” publications, “So the question is: Are lichens plant pathogens? And the answer is: No! Lichens are not plant pathogens. They use a tree or another surface as a substrate to grow epiphytically [and derives its moisture and nutrients from the air, rain…]. Lichens are not parasites and do not derive any nutrients from the host they are growing on. Lichens may grow on healthy as well as stressed trees. They are more noticeable on stressed trees because of the open or thinner canopy.”

If your tree’s canopy is thin during the growing season and if you can see the lichens easily, then your tree is having other issues, perhaps related to fertilization, drought, root damage, etc.


An oak street tree with a possible diagnosis of bacterial leaf scorch.
Photo: Carolyn Barber, Mandeville, LA.

Bacterial Leaf Scorch

Earlier in the growing season, Carolyn and Ed sent a very concerning email, “Please tell us what to do to save our oak tree. We are guessing too much water. We are thinking that we should not had our sprinkler system on this month after the monsoon rain in May in Mandeville.”

Based on this image, AHA suspects that this tree has bacterial leaf scorch (BLS). The LSU AgCenter has a publication, “Bacterial Leaf Scorch of Landscape Trees”, and it lists the tree species susceptible to BLS. Leafhoppers or spittlebugs are the main insects spreading this disease. Currently, there is no treatment. However, pruning out infected branches may extend the life of the tree.


Pine siskins.
Photo: LA Master Naturalist of Greater Baton Rouge.

Birdfeeder Habits

A recent RSFF discussed the possible effects of bird droppings on soil pH under a bird feeder. Christy, a Master Gardener from Pineville, shared her comments about the feeding habits of some birds, “[I read RSFF] about the bird droppings near a feeder: I have seen what appears to be growth inhibiting effects of sunflower hulls below my bird feeders. However, I think the myth about toxins from hulls may not be substantiated. But the mold I have seen associated with a thick layer of hulls is real….and without the mold a hull layer seems to perform like a mulch.

I have never seen much effect from bird droppings since most birds I am attracting with oil sunflower don’t hang around the feeder and usually fly off with a seed. That is NOT the case with feeder hogs like American goldfinches and pine siskins who will be parking on thistle and sunflower feeders soon with arrival of the cold weather.

However, my bird feeding observations are limited to oil sunflower. Others may see different bird behavior, including more droppings with other seed mixes and what those mixes attract or cause when any hulls or seeds fall to the ground. Mixes for “wild birds” are generally a waste in my opinion, but many people use them.”


Yellowing or chlorotic leaves of a muscadine vine.
Photo: Tom Avant, Sugartown, LA.

Ailing Muscadine Vine

Again, AHA went into the inbox and found a complaint from Tom about one of his muscadine vines, “This muscadine is chlorotic and has almost no fruit. Can you tell me what is wrong? All others are fine.”

The yellowing or chlorotic leaves seems to indicate a lack of nitrogen and perhaps other nutrient deficiencies. A soil test can help with adjusting the nutritional needs of this plant.

The lack of fruit may because some muscadine plants have only female flowers and will need another muscadine plant with both female and male flowers. These male flowers can help with pollination of all muscadine vines.

If you want to contact Roots, Shoots, Fruits and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 318-264-2448 or Also, please share the name of your parish.

“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.”

12/16/2021 9:47:32 PM
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