I don't know if I "sterilized" it, but I was given a potted
rose bush that had Black Spot really bad & I took it out of the pot & THOROUGHLY washed the roots off (in my driveway, away from other
plants). I sprayed straight #### on the roots & re-potted it in a fresh pot with new soil, then kept it watered (with #### solution only for about 2 weeks). I took the pot, all the diseased leaves, & the soil that the
plant came in, to the dump... which may have been an extreme move, but I didn't want the contamination anywhere in my yard! The
rose didn't seem to root-shock from my harsh treatment, & it perked right up & flourished in a short time! I'll be transplanting it to a permanent location, now that I know it's healthy.
If I have a
plant that shows symptoms of a disease or is sick from over-fertilizing or other chemical mistreatment, I have the attitude that if I lose it by doing something harsh to it, "OH WELL! If the
plants in my yard can't be healthy & happy I don't want them here anyway!"
But then again, what do I know?... I'm so new at this stuff that maybe the success in my methods has been dumb beginners luck & might not work ever again, once I know all the "rules"!