I have some privet trees in the back yard that I’m going to work to remove this fall. I am generally a no-herbicides guy, but I make some exceptions. Poison ivy is my first exception. I’m fine with it in the wild, but I don’t want it in my yard, and I’m not going to pull it up manually.

I suppose privet will be my second exception. I will pull the smaller saplings if I can, but the full-grown trees will need more. The Georgia Native Plant Society has this nuanced article on using herbicides as part of a plan to manage invasive species.

The main methods to control privet are:

• manual (pulling it up, roots and all)
• spraying the leaves with herbicide
• spraying the cut stump with herbicide (“cut-and-treat”)

Given the trees are big, I will not be able to pull them up. And I don’t want wind-blown herbicide from a leaf spraying. So I plan to cut them down and treat the stump. The cut-and-treat method.

These trees are in a currently unmanaged part of the yard dominated by english ivy and liriope, so I’m not concerned by the immediate collateral damage of treating the privet. I do worry a little about the herbicide being taken into the soil and affecting what I plant there in the future. From the information I’ve found, the commonly available glyphosate and triclopyr herbicides don’t have that problem, while imazapyr does. So I will avoid imazapyr and look for glyphosate or triclopyr.

The next big question was “ok, but at what concentration?” Below are a bunch of resources on privet and privet control, and I’ve pulled out each resource’s answer to that question.

The general idea seems to be a end solution of 20–50%. So that’s my plan. Cut and then immediately treat with 20–50% solution of glyphosate or triclopyr. For reference, Roundup Weed & Grass Killer 4 is 0.122% triclopyr. It’s hard to find a product in the recommended range, but I know I’ve seen something at my local Ace that is in the range.

Below are the resources I used to get to this plan.

Giant disclaimer: I’m just a dude on the internet. Please use expert advice in your own life.

• Trees Atlanta: How to Remove Privet

  Trees Atlanta has a good overview of methods of control. For privet cut-and-treat, they suggest a 20–50% glyphosate solution. They also have information on other invasive plants in the area.

• Invasive Plants of Georgia’s Forests: Identification and Control

  This is a 2006 publication from the Georgia Forestry Commission, University of Georgia, and USDA Forest Service. It has an overview of invasive plants in general as well as specific plants. It does not specify cut-and-treat. It seems to be geared towards larger areas of privet.

• Southeast Exotic Pest Plant Council Invasive Plant Manual: Privet

  I couldn’t find a clear date of this publication, but the introduction ends with “6 - 2003” which makes me think it’s from 2003. There’s a lot of information here. For privet cut-and-treat, it says to use a 25% glyphosate or triclopyr solution.

• Alabama Cooperative Extension System: Control Options for Chinese Privet

  Good info on privet control. For cut-and-treat, it recommends making a 25% solution of glyphosate or triclopyr amine.

• Northeast Georgia Invasive Plat Cooperative: Managing Invasive Plants in the Georgia Piedmont

  I didn’t see a date on this publication. It has good overall information on invasive plants and on chemical treatment. For privet cut-and-treat, it says to use a 21% (“half water and half 41% active ingredient”) glyphosate solution.

• Invasive.org: General Principles for Controling Nonnative Invasive Plants

  I found this from Invasive.org, but nothing on the publication itself identifies the source, and it is clearly part of a larger publication given the page numbers. It has good general information. For privet cut-and-treat, it recommends

  cut large stems and immediately treat the stumps with Arsenal AC* or Velpar L* as a 10-percent solution in water (1 quart per 3-gallon mix) with a surfactant. When safety to surrounding vegetation is desired, immediately treat stumps and cut stems with Garlon 3A or a glyphosate herbicide as a 20-percent solution in water (2.5 quarts per 3-gallon mix) with a surfactant.

  *Nontarget plants may be killed or injured by root uptake.

• PennState Extension: Privet

  Good overall information on privet and it’s control. For cut-and-treat, it recommends either “Pathfinder II or Garlon 4 Ultra (triclopyr ester)” as “Ready-to-use or 20%, 1:4 in basal oil” or “Aquaneat (glyphosate) or Garlon 3A or Vastlan (triclopyr)” at “50%, 1:1 mix with water.” Given the information from other resources, I think the “50%, 1:1 mix with water” means a 50% solution diluted by half, so 25% solution. Otherwise I think the differences between the two options here are oil-based vs water-based.

• UT Extension: Privet (Ligustrum spp.)

  This publication looks to be from 2009. For cut-and-treat, it recommends “2 to 4 oz ai/gal imazapyr”. This is the first I’ve seen imazapyr as an active ingredient.

• Illinois Extension: Invasive Privet

  An overview of privet (with some Illinois-specific context). For cut-and-treat, it recommends

  Apply triclopyr amine in water or ester in oil at a 20% to 25% v/v rate or glyphosate at a 25% to 50% v/v rate in water within 10 minutes of cutting.

• Missouri Invasive Plant Council: Invasive Privets

  A brief overview of privet with a cut-and-treat recommendation of 10–20% glyphosate solution.

• Ohio State University Extension: Controlling Non-Native Invasive Plants in Ohio Forests: Privet (Ligustrum spp.)

  This page has a lot of information and multiple options for cut-and-stump. It recommends any of:

  • Glyphosate for non-aquatic sites (Imitator Plus, Glyphosate 4 Plus, Roundup, Roundup Pro, or other glyphosate products with 41–54% active ingredient): 20–50% or 26–64 fl oz in enough water to make 1 gallon
  • Glyphosate for sites near water (Accord, Aquaneat, Rodeo, Roundup Custom, or other glyphosate products with 41–54% active ingredient labeled for use in or near aquatic sites): 20–50% or 26–64 fl oz in enough water to make 1 gallon
  • 2,4-D + Picloram (Pathway and Tordon RTU): ready-to-use
  • Triclopyr (Element 3A*, Garlon 3A*, Tahoe 3A*, Triclopyr 3*, Triclopyr 3A*, Vastlan*): undiluted
  • Triclopyr (Element 4, Garlon 4, Garlon 4 Ultrua, Relegate, Remedy Ultra, and Triclopyr 4): 20–30% or 26–28 fl oz in enough oil carrier to make 1 gallon
  • Imazapyr** (Arsenal, Chopper, Polaris SP): 6–8% or 8–10 fl oz in enough oil carrier to make 1 gallon

  * Label with “Danger” or “Warning” due to potential eye damage
  ** Imazapyr products are phytotoxic in small amounts and have soil activity that can cause injury to non-target plants.