Daniel Gill, Merrill, Thomas A. | 6/29/2007 11:58:50 PM
By Dan Gill
LSU AgCenter Horticulturist
I recently came across some poison ivy as I was working in an out-of-the-way area of my landscape.
Poison ivy is very abundant in urban, suburban and rural landscapes. I keep a sharp eye out for this plant, since I’m quite allergic, and I promptly and ruthlessly deal with any as soon as I see it.
Recognizing Poison Ivy
Poison ivy is a tall-climbing vine that is leafless in winter (deciduous). As it climbs tree trunks, wood fences or other flat structures, the stem produces many small roots that cling to the surface. This is a good identifiable characteristic of the vine in case you can’t easily see the leaves.
Poison ivy plants are very common along fence and at the base of trees, and seedlings often are found in garden beds.
Poison ivy has a characteristic compound leaf consisting of three leaflets (Hence the saying, "Leaves of three, let it be!"). The leaves are 2 inches to 4 inches long and dull or glossy green with pointed tips. The middle leaflet generally is larger than the two laterals. The margins of the leaflets are variable, appearing irregularly toothed, lobed or smooth. The leaves are arranged alternately on the stems. Young foliage often is shiny or oily-looking with a reddish tint.
Mature poison ivy vines growing up trees flower and produce a white fruit, which is readily eaten by birds. The birds spread the seeds through their droppings, thus creating the wide occurrence of this plant. New seedlings of poison ivy are easily overlooked. They may have a reddish tint to their foliage and will appear upright. As they get older they will begin to vine and grow up nearby shrubs or trees. It is easy to come into contact with young poison ivy seedlings when weeding flower beds, so you need to be observant.
Another common vine in our area, Virginia creeper (Parthenocissus quinquefolia), is a non-poisonous vine that is often mistaken for poison ivy. It has five leaflets radiating from one point of attachment on mature leaves, which distinguishes it from poison ivy, which has three. The leaflets also have a different marginal appearance.
Controlling Poison Ivy
In controlling poison ivy, one of the most important things to do is to periodically check your landscape carefully for seedlings or vines. Look for the three leaflet leaves in out-of-the-way areas, under shrubs, along back fences and by trees.
Three methods can be effective in eradicating poison ivy in the landscape.
The first is hand pulling or digging out when the soil is moist – getting out as much of the roots as possible. Use long gauntlet rubber gloves, which are available at local hardware stores, or dishwashing gloves when handling the vines. Place the plants into a plastic bag, seal it (in consideration for trash collectors) and throw it away. Be sure to wash your gloves with soap and water after handling poison ivy.
The second eradication method is to carefully spray the foliage with a systemic herbicide. This is only possible when the spray will not get on the foliage of desirable plants. If needed, nearby desirable plants can be covered with plastic sheets or bags to protect them while you do the spraying.
Be sure to wet the foliage of the poison ivy vine thoroughly. Systemic herbicides are absorbed by the foliage and enter the plant’s circulatory system, which sends the material into the vine’s roots and kills them as well. Glyphosate (Roundup, Eraser, Hi-Yield Killzall and other brands) or triclopyr (Brush-B-Gon, Brush Killer and other brands) are commonly recommended for poison ivy control. Herbicides that contain a combination of dicamba (banvel) and 2,4-D also work well.
With this method, once the vine dies it may be removed. Just remember that the dead leaves still contain the catechols and should be handled cautiously with gloves.
The third method to get rid of poison ivy is for larger, more established vines that growing up in trees or intertwined in the landscape. Spraying the vine foliage is not practical in these situations because of the potential to injure desirable trees and surrounding landscape plants.
Poison ivy control in such sensitive areas can be best achieved by the "cut vine" method. Cut off the vine a few inches from the ground with loppers and immediately treat the fresh-cut stump with undiluted triclopyr (Greenlight Cut Vine and Stump Killer). The vine in the tree or landscape will die because it has no root system. The treated stump will die because the herbicide gets absorbed by the freshly cut surface and translocates to the roots. Applying the herbicide to the fresh cut is necessary because it prevents the stump from sprouting again. This method is very effective and may be used any time of the year.
Getting poison ivy off your property will probably take repeated herbicide applications. Older vines in neighboring yards may continue to drop seeds in your landscape that will sprout and bring poison ivy back to your yard again. So watch out for this unwelcome plant and be prompt and aggressive in your efforts to control it.
Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com . A wide range of publications and a variety of other resources are available.