For years on GardenLine, I've said that you need a brush-killer herbicide to control dreaded poison ivy and poison oak vines.

That means using something with the active ingredient triclopyr.

Lately, I've been getting questions about other unwanted vines as well, and I've been telling those folks to go with the solution for poison ivy. But after a flurry of related calls to the radio show last weekend, I'm providing the overview I promised and an update on killing unwanted vines.

Getting advice on this topic has been a problem, because I and many unsuspecting homeowners have found that the product Roundup (a glyphosate-based herbicide) is often recommended by nurseries and garden centers. Glyphosate is a "weed and grass herbicide" originally invented to control Johnson grass, but it's not really intended for woody or semi-hardwood vines. I get countless calls and emails from people who've tried Roundup and found it didn't work on their vine. Or that it burned the top leaves but didn't kill the plant.

treeI think I've discovered why Roundup is so often wrongly recommended. I've researched over 50 websites associated with the eradication of poison ivy, and apparently Roundup (glyphosate) does work pretty well, but only when used on brand new growth ... before it can become a woody vine. So for Roundup to be effective, you have to physically remove as much of the vine as possible, then be on the lookout for new growth.

So triclopyr-based products are really the way to go. There are several on the market these days that are applied sort of like you'd use a glue bottle — first, cut everything away, then ooze the herbicide on the fresh-cut stumps.

treeBut when I think about poison ivy control, I always envision just spraying the leaves, which means it's critical to add a surfactant to the mix so the herbicide will adhere and not drip to the ground. I also have used a "wicking" method with triclopyr-based controls. Wear a rubber glove covered with a cloth-style gardening glove, and dip your gloved hand into the control solution. You can then use the wet glove to hand-treat individual leaves or clusters.

Finally, there's the "baggie" method with triclopyr-based herbicides. Fill a thick freezer-type ziplock-style bag about 1/10 full of undiluted herbicide and, wearing gloves, stuff into it as much live poison ivy vine as possible. Close the zipper as far as possible and swirl the herbicide around so it coats most of the leaves. Use a clothes pin to hang it upright, so the herbicide won't leak out. The plant will absorb all the herbicide down into itself. You should still remove all the dead poison ivy eventually, especially if you are highly allergic. (I know many are so allergic that just the thought of trying to remove the vine makes them itch.) Remember that dead poison ivy still contains poisonous oils.

Meanwhile, here are all the control methods I found on various websites:

Amitrol-T or Weedazol (amitrole) - They work in the same manner as glyphosate, but remain active in the soil for several weeks after application. That means you can't plant new vegetation in the treated location for awhile, and you should not use these products in soil where food crops will be grown or in animal grazing areas. Amitrole may be listed on a label as "3-Amino-1,2,4-triazole."

Weed-B-Gone, Jet Weeder - These and other products containing 2,4-D are not the most effective solutions for controlling poison ivy, but 2,4-D does not kill grass. It may be mixed with 2,4-DP when used on larger "woody" poison ivy plants for increased effectiveness. Repeated treatments will probably be required, as it usually will not kill the root system through a single application. Apply at least 6-12 hours before watering or anticipated rainfall. The active ingredient may be listed on the label as "diethanolamine salt of 2,4-Dichlorophenoxyacetic acid" (for 2,4-D) or "diethanolamine salt of 2,4-Dichlorophenoxypropionic acid" (for 2,4-DP). Note: Some plants are very sensitive to extremely small amounts of 2,4-D and 2,4-DP. If you must use the sprayer later for the application of other materials, rinse it carefully several times with an ammonia solution (including the nozzle, hose, reservoir, etc.) to remove all traces of 2,4-D and 2,4-DP.

Brush Beater, Redeem, and Brush-B-Gone - These are triclopyr and work in a manner similar to 2,4-D, but have longer soil activity. They do not affect grasses, but you should not plant trees in treated soil for at least six months.

Crossbow - This is a mixture of 2,4-D and triclopyr and is one of several herbicide mixtures that may be the best at poison ivy control. But good luck finding it. Read the label carefully for the effects of such mixtures.

Roundup and Kleenup - Both are glyphosate which has no soil activity. Applied to the leaves of brand-new poison ivy growth, it is absorbed through the leaves and carried throughout the entire plant. After spraying, do not try to remove the plants for several days so the absorption is complete. (Don't forget that the dead vine still contains the oils that cause irritation.) Avoid over-spraying as glyphosate will kill adjacent plants, including grasses. Glyphosate may be listed on a label as "isopropylamine salt of glyphosate."

Not all the listed products may be available in your area, and some may not be allowed for homeowner use without special licensing. In fact, there's little chance that anything more than glyphosate, and possibly triclopyr, are available at most nurseries and garden centers. However, good old-fashioned feed stores and specialty chemical shops will have a wider variety. There, you may also find products for non-residential control of poison ivy, like along fence lines. Banvel, Velpar, 2,4-D ester+2,4-Dp ester, Tordon, and Oust are examples.

If you're just itchin' to learn more about poison ivy, poison oak or poison sumac, there are a number of websites focused on the plants' irritating aspects. A couple to see: and