yep, sometimes they blister up.... It did that last time on my Sourapples , they close for a couple weeks after that treatment and blister up. after that they're back to their usual. I had some type of clear feathery type fungus starting to appear on them. Furan2 didn't do the job so I did the peroxide treatment. Haven't seen it since and the SourApples looking real good now. I've also used this treatment on PE's as well. Im trying it on polyp pinching to see if it helps, right now when I have some polyps pinching bad, they usually don't make it on me. I've since started dipping the polyps in peroxide and it's lengthening its longevity but still pinching a little but not as bad.