Your method is exactly what I would do, reducing the root mass and the plant - makes perfect sense and should work out for you. Also, you don't need a special tool. any saw, garden lopper, etc... for that type of root removal. For the record a lopper is easiest to clean - I use 91 % Isopropyl or Clorox Clean-Up whichever is handy at the time.
As a follow up and a preventative I would strongly recommend dosing those two after cleanup and potting with Sulfur. It is inexpensive and I have read several studies that indicate it does a real nice job of stopping root gall from occurring when plants were exposed on purpose to the infection. It is also an effective product to use on a wide variety of plants that have cedar rust. I would also treat other plants in close proximity as a precaution.
This pound of powder costs 10ish USD. I mix two tablespoons with 1 gallon of water and soak it through after watering once a week during Spring and Summer. After leaf drop I give the plants heavy soak once in Fall and another just prior to Spring bud break. This pound container will make many gallons, most likely enough to last at least a few seasons. -
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Grimmy
but hopefully someone else can chime in on this resurrected thread.
