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I've been running into a fairly significant problem this summer.  I've encountered a great deal of POISON IVY (Toxicodendron Radicans)lately.  I’ll also include in this discussion poison oak and poison sumac.  All of this stuff is mean.  My wife came in contact with some in our yard.  I had a coworker who almost had to go to the hospital because of it.  I am just as susceptible.  It is some terrible stuff.  Some horticulturalists are saying the cultivars of poison ivy out there now have become MORE toxic than in earlier years, citing increased carbon dioxide in the atmosphere.  And, the poison ivy is not just along some remote fence line, way in the back, behind a shed.  The poison ivy is right there, in a front yard bed, growing through the existing landscape.  How do we deal with, and hopefully get rid of, poison ivy? 



The first method would involve what we call “cultural” methods or controls.  That is the practice of modifying the growing environment to reduce the prevalence of unwanted pests or plants.  First of all, this method may expose you to the toxin.  If you are susceptible, you would need to wear protective gear (gloves, long sleeve shirt, breather/mask, etc.).  No gaps in clothing.  You can also get exposed to the toxic oil “Urushiol”, the plant’s sap, from clothing, tools, or other objects that have been in contact with the plant.  You will have to “disinfect” anything that comes in contact with the plant.  That is, anything you want to use again.  Even dead plants can get you scratching.  When it is hot out, you’re perspiring and your pores are open, you are really vulnerable.  



Repeated cutting of the plant back to the ground surface will eventually starve the root system and the plant will die.  However, repeated cutting increases the chances of exposure to the toxic oil.


Hand-pulling, grubbing or hoeing poison ivy out of the ground are difficult, but can work with small infestations.  These techniques are rarely successful on infestations that have been established for two years or more.  Best results will be achieved when soils are wet.  Pulling roots from dry soil is futile.  Eradication will only be achieved if all portions of the underground rootstocks (rhizomes) are removed from the soil.


Then there is “chemical” control.  Remember what I said earlier in this blog about SELECTIVE herbicides?  Selective herbicides kill specific targets, while leaving the desired plants relatively unharmed.  BLUF (Army talk for: Bottom Line Up Front): There is NO selective herbicide that kills poison ivy and does not harm anything else.  That selective herbicide simply does not exist.  There are some “old wives’ tales” out there regarding treatment; vinegar, coffee, hot water.  I’m going to try to keep this somewhat scientific.



Several herbicides can be used to eradicate poison ivy over time.  One of the most effective active ingredients is “Triclopyr”, a selective herbicide that kills broadleaf plants but does not harm grasses.  But, I say again, it is not FULLY SELECTIVE.  It is also good with conifers but it may harm other plants.  One common example is Ortho's “Brush-B-Gon” Poison Ivy Killer or Ortho's “Kleeraway Grass & Weed Killer”.  The best tactic is to look on the herbicide label for the active ingredient triclopyr.  Another selective herbicide possibility for poison ivy control includes products that contain combinations of the active ingredients dicamba and 2,4-D.  These are two out of three of the main selective herbicides for broadleaf weed control in lawns (the third being Mecoprop-p).  These two active ingredients are commonly packaged together in a variety of broadleaf lawn herbicide mixtures.  Each of these active ingredients (triclopyr, dicamba, and 2,4-D) is a selective herbicide that can be used safely on grasses to control or suppress broadleaf plants like poison ivy.  However, due to the potential for volatilization and off-site movement, these herbicides should not be applied in locations where other sensitive species grow in close proximity to poison ivy.  The other sensitive species could be any woody ornamentals; from azaleas to boxwood. 


Glyphosate is another active ingredient that is effective on poison ivy.  That is the active ingredient in “RoundUp”.  But, glyphosate is a NONSELECTIVE herbicide unlike triclopyr, dicamba and 2,4-D.  A nonselective herbicide kills everything and anything.  Glyphosate can kill both grass and broadleaf plants, so care must be taken when using this product near trees, shrubs, flowers or other desirable species.


Either selective or nonselective herbicides should be applied during periods of rapid poison ivy growth to ensure maximum kill.  One of the best times to apply herbicides to poison ivy is just before the plants are blooming.  Although you may apply any of these herbicides at the right time and in the right amount, keep in mind that poison ivy is a tough perennial plant with thick, woody rootstocks, and therefore re-growth and new sprouts are likely to occur.  If this is the case, be sure to make repeat applications during the same season or in the following year to achieve complete eradication.  Whenever you use any herbicide, be sure to read and understand instructions on the herbicide label before making an application.


I talked about this before, but here’s a review.  You may need to know these definitions:  Contact herbicides destroy only the plant tissue in contact with the chemical.   Generally, these are the fastest acting herbicides.  They are less effective on perennial plants, which are able to re-grow from rhizomes, roots or tubers.  Systemic herbicides are translocated through the plant, either from foliar application down to the roots, or from soil application up to the leaves.  They are capable of controlling perennial plants and may be slower-acting, but ultimately more effective than contact herbicides.


Glyphosate is a systemic herbicide.  So is triclopyr, dicamba, and 2,4-D.


A couple more trade names are “Crossbow” (a 2,4-D/triclopyr combo), “Triple Threat Broadleaf Weed Killer” (2,4-D & Mecoprop-p), “Weedmaster” (a dicamba plus 2,4-D mixture) and “KLEENUP” (Glyphosate)


Some of the more “earthy” horticulturists use “St. Gabriel Labs' Poison Ivy Defoliant” (Clove Oil, Sodium Laurel Sulphate, Vinegar, Lecithin, Water, Citric Acid, and Mineral Oil).


You could do a “mix” of cultural and chemical control.  Like cut the main stem just above the ground and try to pour the herbicide right down on to or immediately adjacent to the main stem.  Try not to pour too much so it leaches into the root systems of nearby plants.


Herbicide application by “painting” (like with a brush) on to the leaves is suitable for some locations.


Never burn poison ivy.  If the smoke gets in your lungs, that’s a trip to the emergency room.


Finally, there is a radical solution.  But, I guess it is not that radical if you have a real severe infestation.  You could transplant your all of the desirable plants out to another location, really nuke the area with an herbicide, and then bring the plants back to their original location.  Fortunately, the herbicides I mentioned do not have a long life in the soil.  It is not like you’d have to keep your plants elsewhere for several months.  Obviously, this has to be done during the growing season wherever you are and there must be ample time for the plants to re-establish themselves. 


I guess there is one more possible method of eradication.  Goats love poison ivy.  You could get a goat.


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