Roots, Shoots, Fruits & Flowers: Pond Weed, Ornamental Shrub, and Black Turpentine Beetle

39_Fig_1_pond_weedjpgEither Alligatorweed or water primrose. Photo: Darren Smith.

It's either alligatorweed or water primrose

Darren sent an email and a picture and went straight to the point, “What is it?” He was asking about an aquatic weed in a pond. Also, the implied question is “What do I use to treat this weed?”

AHA consulted with Kevin Savoie, an area agent in fisheries, and Savoie sent this message, “[This weed is] either alligatorweed or water primrose. Treatment is the same for both. Spray glyphosate and 2,4-D (1 oz per gallon each plus 1/2 oz. per gallon surfactant).” A surfactant reduces the water tension and enables the herbicide to treat a target plant more effectively.

39_fig_2_photiniajpgLeaves and flowers of Photinia. Image: Wood Johnson.

Photinia

Wood J. of Pineville also sent a concise question and some images, “Can you identify this plant? … There are several of these shrubs on the side of the road near Pineville. My former coworker collected the samples. He said he thought they may be escapes from nearby neighborhoods.”

Again, AHA consulted with horticultural specialists at the Hammond Research Station, and they think this specimen in the image is photinia. Sometimes this shrub is also called red-tipped photinia because of its red foliage during the growing season.

According to an extension horticulturist with the University of Arkansas, “The Redtip Photinia is a large evergreen shrub that can reach 15 feet with a spread of 10 feet or more. In the spring, and during the summer as new flushes of growth appear, shoots emerge in a blaze of red leaves. The 5-inch long leaves remain red for two to three weeks and then turn a glossy green.”

39_fig_3_black_turpentinejpgPitch tube by black turpentine beetle. Photo: Jason Gresham.

Pitch tube from a yellow pine tree

Silas sent in this image of a pitch tube from a yellow pine tree in LaSalle Parish:

The pitch tube shown in the image occurs on the bottom eight feet of a trunk of a southern yellow pine, and the black turpentine beetle (BTB) is the pest causing this damage. According to the US Forest Service, BTB attacks southern pines during stressful periods like a drought.

To prevent infestation by BTB in the landscape, the University of Florida shared these recommendations:

  • avoiding compaction of, physical damage to, or pavement over the root zones of pines,
  • avoiding trunk wounds,
  • providing adequate spacing (4-6 m) between trees,
  • minimizing competing vegetation beneath pines,
  • maintaining proper soil nutrient status through an acidic needle or pine bark mulch over the root zone, and by not routinely watering turf grasses beneath pines, and
  • providing supplemental deep watering during extended drought periods.

Homeowners can also treat the trunk with permethrin or bifenthrin insecticides. Dr. Dale Pollet, retired AgCenter insect specialist, makes this recommendation, “When treating, one should use either diesel fuel or an oil with the insecticide to help it penetrate the bark to provide better management.”

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 khawkins@agcenter.lsu.edu. 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.”

3/10/2020 7:24:48 PM
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