Start with a gallon of white vinegar. The “average” vinegar is 5% acidic and will work just fine, but if you can find one that’s 10% or 20% your mixture will be more potent. Pour the vinegar into a pot and heat it over the stove. Add 1 cup of salt and stir until the salt dissolves. Let it cool, then add 2 tablespoons of liquid dish soap.
Vinegar, when diluted with a gallon of water makes a good fertilizer for acid-loving plants like azaleas, rhododendrons and blueberries. When mixed full strength with salt, it works very much like Round-Up. The dish soap helps the mixture to stick to the leaves.
Pour the mixture into a spray bottle. Set the sprayer to stream (not mist) to for better control. Once again, be careful where you spray because it will damage any leaf that it hits.
Be Patient
Spraying your plants with a systemic herbicide or the vinegar mixture will not work overnight. After its absorbed into the leaves it takes time before it destroys the root system. Give it 2 weeks, then spray the plant again if necessary. It may take more than one application to do the job. Poison ivy is a tough plant with strong roots.
= new reply since forum marked as read