English Ivy

You might want to file the following under "stuff I already know" but I thought I should share this with you anyway. It comes from comments on the speakers circuit this winter as well as conversations last week in Charlotte at the meeting of the NC Exotic Pest Plant Council (EPPC) by people who I thought should know better.

The topic was English Ivy. I was told it had been outlawed. This is not true in NC. It is still perfectly legal to plant English Ivy in North Carolina. The state of Oregon has put English Ivy on its noxious weed list, not NC. Oregon is a very different place from NC with different problems and a different climate.

Next I was told that English Ivy is invasive and out of control and taking over the woodlands. I showed pictures of English Ivy cloaking trees in my talk, in fact, and talked about the responsibility of gardeners to be stewards and to try to keep their pets, plant or animal, from causing problems to the neighborhood.

My first response, when folks talk about an out of control garden plant, is "Have you tried to control it?" If the answer is yes, I ask what they have done.

I've talked this over with Dr. Joe Neal and he suggested I share the contents of HIL 648 (NCSU Horticultural information leaflet #648) via this in-house Extension newsletter as a reminder . . . this is the time of year for a teachable moment. TIMING is critical when trying to control English Ivy. Table 2 of HIL 648 is entitled Optimum application rates and timing of Roundup-Pro (glyphosate). It is subtitled Amount of Roundup-Pro to Obtain 90% or Better Weedy Species Control One Season Later, Application Timing for Best Control. Joe writes that English Ivy should be sprayed with a 2 or 3% solution when 3 to 5 fully expanded new leaves exist (early spring). This is based on his research and is not on the product label.

I know from personal experience that this approach works and spraying when we go after blackberries in fall and early winter is almost completely ineffective. Joe also points out that a 3 % solution when there are five fully expanded leaves is also the time to control Greenbrier (Smilax spp). Early spring is the time for control of this plant with Roundup, not fall.

From a horticulturists point of view, I know the 90% control depends on coverage. Even then, in old stands where there are multiple layers of vines and roots, full control . . . if ever achieved . . . will require at least two or three years of persistence and respraying each spring. The 10% that remains will regrow if it is not sprayed or physically removed.

English ivy plants that are up in trees should have stems cut to separate most of the growth from roots. New growth from the roots can be much more easily and safely sprayed than vines in trees. Please do not recommend that folks spray Roundup into the canopy or up the trunk of trees. Eventually, nature will take its course and the vines will die but the vines will not die quickly and they will be unsightly unless removed.

In a personal communication on the subject, Dr. Neal offered the additional advice: An alternative which often works better than spraying the foliage is to treat the freshly cut stems with Roundup or a brush killer containing triclopyr (sold as Ortho Brush B Gon, Brush Killer, Poison Ivy / Oak Killer, & others). For Roundup -- a 50% (by volume) solution is recommended for cut stump applications. Check the label of the herbicide you choose for cut-stem application directions. Again, this is best done in the spring for English Ivy. Cut the stem close to the ground and apply the herbicide solution to the fresh cut.

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