For years on the GardenLine program, I’ve said that if you want to control the dreaded vines of poison ivy and poison oak, you need to use a brush killer herbicide. That usually meant something with the active ingredient triclopyr.
But a problem I and many unsuspecting homeowners have found is 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), not a woody-vine or semi-hardwood herbicide.
I get countless calls and e-mails from those who’ve tried Roundup and found it didn’t work. Or that it burned the top leaves but didn’t kill the vine.
Now, I 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 when used on BRAND NEW GROWTH … before it can become a woody vine. That means to use Roundup effectively, you have to physically remove as much of the poison ivy as possible, and then be on the lookout for new growth.
What if you are allergic to poison Ivy? So allergic that just the thought of trying to remove the vine makes you itch? Well, here are all the control methods I found on the sites:
- Amitrol-T or Weedazol (amitrole) work in the same manner as glyphosate, but remain active in the soil for several weeks after application. This soil activity would delay planting new vegetation in the treated location. Do 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 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 nozzle, hose, reservoir, etc.) to remove all traces of 2,4-D and 2,4-DP.
- Brush Beater, Redeem, and Brush-B-Gone (triclopyr) work in a manner similar to 2,4-D, but have a longer soil activity. They do not affect grasses, but you should not plant trees in treated soil for a period of at least six months.
- Crossbow (a mixture of 2,4-D and triclopyr) is one of several herbicide mixtures that may control poison ivy. Read the label carefully for the effects of such mixtures, as well as for any herbicide applied around the home.
- Roundup and Kleenup (both are glyphosate which has no soil activity) may be 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. Remember that dead poison ivy still contains poisonous oils. 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 of 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 of choices. 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, for example.
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.