Ask OGS: Organic Herbicide for Poison Ivy
Dear OGS,
Is there a “safer” more organic version of Roundup to kill poison ivy? Handling it with hands and goats inevitably ends up in someone getting a bad rash.
Thanks,
Lee at Earthaven in WNC
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Poison ivy plant
Lee,
Looking at couple catalogs that supply WNC, I see several products which may be useful:
Burnout II Weed and Grass Killer (gallon about $41)
St. Gabriel Poison Ivy Defoliant (gallon about $39)
Final San-O (2.5 gallons for about $84)
McGeary Corn Gluten (40# covers about 2000 sq ft for $32)
Corn gluten is unlikely to help with poison ivy since it affects seed germination and established plants are unlikely to be damaged. The other three products are defoliants, meaning that the spray affects green leaves but none of these products suggests that they will systemically kill perennial weeds like poison ivy. They may be useful in temporarily reducing exposure to oily leaves. They may also be useful if the grower has patience enough to spray repeatedly.
Each time a poison ivy plant produces a new set of leaves it uses up energy reserves which the green leaves restore over time. I have heard that trees defoliated by insects can tolerate about three years of defoliation before they give up. I imagine that small vines have fewer reserves than trees so repeated defoliation might work. I suspect that more than one season of repeated spraying may be needed but I have not tried this approach.
Flame weeders, high pressure steam, and concentrated vinegars are other approaches that I have heard mentioned for “organic” weed defoliation. I suggest extreme caution in burning ivy, even if it is just the leaves. Airborne oils are likely to be a more serious problem than exposure to the leaves. Homemade spray recipes exist, for example, but they may not be allowed for certified farms.
From gemplers.com
I know from experience that mowing works to “wear out” poison ivy. When perennial crops make mowing impossible, shoulder length rubber gloves are my tool of choice. After a rain or irrigation is a great time to pull poison ivy. I am only moderately sensitive to poison ivy oils and rarely see a reaction even after an hour or so of pulling vines. Some crew members in the past have been so sensitive that they cannot even be near poison ivy so use this method with caution if you are particularly sensitive. Most suppliers of spray equipment will have a variety of heavy duty gloves.
Outside crop areas, Roundup or similar products can be effective. Organic rules require a fifty foot buffer between areas where prohibited materials are used and organic crops. Ecosystem restoration experts that need to control invasive plants suggest poisoning stumps with herbicides designed for that purpose. A beauty parlor hair color applicator seems to work well with no opportunity for spray drift. For giant ivy vines outside your certified growing areas, this approach may be worth considering. A chain around the base of a large vine and a tractor might also work. For medium size plants consider a product called a Root Jack. Prevention is an important part of a farm-wide strategy since birds seem to like the poison ivy berries and spread them around.
Root jack
I mention rubbing alcohol in my earlier poison ivy post, but don’t forget thorough clean-up after any work with poison ivy. Rubbing alcohol is far better for exposed skin treatment than soap and water in my experience. I read somewhere that it can unhook the oils from their otherwise very strong attachment to skin. Alcohol dissolves in water too so it can be rinsed away after a liberal application. Alcohol can work to some extent even after a rash appears. Showers are better than baths after using alcohol since ivy oils float on bath water.
Good luck.
All the best,
OGS
This blog post, written and copyrighted by Ruth Gonzalez, was originally published as part of a previous Organic Growers School article series called "Ask Ruth," which addressed the gardening concerns of home growers. Some updates may have been made by OGS staff to keep the content current.