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Rampant Weed Round Up

With our 62 year old house came an acre of yard that had not been tended in twelve years. One large problem is a southeast-facing bed of white irises that grow under the canopy of three pine trees. The bed is glorious in the spring until the vines (VA creeper, tie vine, and poison ivy) take over before the blooms are spent and die back at first frost. We tried pulling up the invasive vines by hand, but the root systems are heavily entrenched and I discovered I am highly allergic to the poison ivy. If and when would it be safe to spray a vine-killing product over the whole bed but not harm the irises?

Re: Rampant Weed Round Up

Never, anything that will kill the vines will kill the Irises. You can put Roundup in a container and brush it on the leaves of the vines being careful not to get any on the Irises.


A. Spruce
Re: Rampant Weed Round Up

When the iris goes dormant, dig up the bed and separate the bulbs from the vines and other unwanted vegetation. From there I would amend the soil, install or repair irrigation to the area, and then replant the iris when you've finished. Any new growth of poison ivy should be easy to pull with a gloved hand which will keep it from taking hold and spreading.

You can minimize your exposure by wearing long sleeves, long pants, and work gloves. If you're really worried you can duct tape your gloves and pant cuffs to prevent skin from peaking out. Once you're finished, put all your clothes into the washing machine, and take a bath with cool water and Fels-naptha soap. A cool bath willkeep your skins pores closed, preventing the oils of the poison ivy from causing irritation.

Don't forget to wash your gloves and shoes with your clothing, and you're going to want to wash down any tools you've used in the area as well.

Re: Rampant Weed Round Up

Irises have a waxy coating and spear shaped foliage which allows the use of the following technique:

Use roundup at 1/2 to 3/4 the recommended dosage. Spray on the vines. If you get some on the irises, it shouldn't hurt them too much as the waxy coating will help defend the irises. Since this is lower than the standard amount of roundup per gallon, it may take a few appilcations. Space the applications a week apart. Spray on dry, hot, afternoons onto dry foliage.

We have used this technique to rid ivy beds of weeds. It works well.

Re: Rampant Weed Round Up

Irises are monocot plants and should be immune to the effects of a 2-4-d type herbicide. But test it on one before you go crazy. I used this technique to rid a patch of dayliles from an Ailanthus (tree of heaven) infestation. The 2-4-d killed the ailanthus (which is a dicot) and harmed not one hair on the head of the daylilies (hemerocallis fulva). P/I is a dicot, but hard to kill even with repeated applications of roundup.
If nothing else, lift the irises and anything else of value, "nuke" the invasives, then replant.

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