Is poison ivy getting the best of you? Are you afraid that English ivy, crawling up the trunks of your trees, is going to kill them?
Trying to kill them by digging the roots out of the ground is futile. Allowing even a small piece of root to remain in the ground will result in the sprouting of a new plant.
The sure method of killing poison ivy and English ivy vines clinging to tree trunks or telephone poles is to inject a herbicide into the stem. The weed killer that I find most effective is either Weed-B-Gone or Trimex. Mix either of the above with an equal amount of water. Using a hatchet or a sharp knife, make a small notch halfway through the stem of the vine near the ground. Using a small disposal paintbrush, dab the mixture into the notched area. I actually use an oilcan that allows me to place several drops of the solution into the cut area. Take extra care not to spill the weed killer on the trunk of the tree.
Spraying the foliage of English and poison ivy this time of year is like spraying water on a duck’s back. Because both poison ivy and English ivy have leaves covered with an oily or waxy coating, killing them by spraying the foliage with a weed killer requires special attention. Both are impossible to kill this way until mid summer, when they have many fully matured leaves.
By using this technique, after the vines have developed many mature-sized leaves, you are assured that the weed killer will be trans-located down and kill the root system.
If the poison ivy or English ivy is crawling on the ground, you have to use a foliage spray to obtain control. Foliar applications of weed killers on either species are most effective applied from July into late September.
Since both species have glossy oil or wax covered foliage, either Weed-B-Gone, Trimex or RoundUp must be amended with ammonium sulfate. Mix two tablespoons of either weed killer and one teaspoon of ammonium sulfate in one gallon of water. The ammonium sulfate is added to dissolve the oils and waxes on the leaves, thus allowing the weed killer to penetrate the leaf tissues. Do not spray the plants if they are stressed due to drought. Spray the foliage only to wet.
If you are using RoundUp, the spray will kill grasses as well. However, Weed-B-Gone or Trimex will only kill the broadleaf plants but not the grasses.
For maximum effectiveness, this treatment must be repeated within 10 to 14 days for poison ivy. To wipe out English ivy, three applications must be made at weekly intervals. The oils and waxes that cover the leaves of these species inhibit maximum penetration into leaf tissues. The ammonium sulfate added to the spray helps in dissolving the protective covering and promotes penetration of the weed killers into leaf tissues.
Killing this year’s crop of poison ivy does not mean your problem is solved. Most likely there are seeds that will sprout new plants. You will have to be diligent and inspect the area yearly and spray as needed.
To do this job, wear protective clothing like rubber boots and gloves. If you must walk through tall plants, I strongly recommend you wear Tyvex coveralls.