​Roots, Shoots, Fruits & Flowers: Lawn Burweed, Citrus Scab & Lichens (Again)


Red circles enclose tiny burweed plants which will produce stickers in the spring.
Photo: Keith Hawkins, LSU AgCenter.

Lawn Burweed

Last week AHA went into his backyard to scout for lawn burweed (LBW) or stickerweed and found LBW. The reason for this activity is to avoid stickers in the spring.

Treatment of stickerweed or burweed needs to occur before March. If you can feel the stickers in the spring, then it is too late to effectively treat LBW. AHA has used Spectracide ® with 2,4-D successfully to control this weed. Another effective treatment is Image® with atrazine. A homeowner may need to check regularly for more germination even after successful control of early LBW. In general, LBW will occur where there is thin turf and in areas with foot traffic. Place like gates, shed entrances and patio edges may have LBW.


An orange with citrus scab.
Photo: Keith Hawkins, LSU AgCenter

Citrus Scab

Jerry brought in a couple of specimens for examination. One item is a warty orange.

This orange is infected with a fungal disease called citrus scab. Mr. Robert Turley, an AgCenter horticulture agent in Lake Charles, shared these recommendations, “Spray trees with a chlorothalonil fungicide such as Daconil or Fertilome Liquid Fungicide on May 1st and again May 15th and June 1st. This should help control the scab. Thorough coverage is essential.

Fruit trees should always be planted in full sun in the best drain soil you can provide to maintain a long live healthy tree.” Another practice is to gather infected fruit and leaves and destroy the infected material to avoid fungal spores from spreading to next year’s crop.


"Reindeer" lichens commonly found on plants.
Photo: Keith Hawkins, LSU AgCenter.


The other specimen Jerry brought were branches from fruit trees covered in lichens.

Lichens on trees and other woody plants are a symptom of a thin canopy and not a cause of a problem. A plant’s health is impaired by conditions like compacted soil or poor soil fertility. Practices can include Clorox treatment to kill the lichens, but the lichens will eventually return. Also, fertilizing with a composted manure as a top dressing can address low fertility, and soil aerifying can loosen compacted soils. A healthy, shady canopy is the best control of lichens.

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 email: khawkins@agcenter.lsu.edu. Also, you can be on the “green thumbs” email list by emailing your request to the same email address.

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

1/23/2020 5:06:58 PM
Rate This Article:

Have a question or comment about the information on this page?

Innovate . Educate . Improve Lives

The LSU AgCenter and the LSU College of Agriculture