I've had this prickley pear outside for 1 1/2 years now. It made it through last winter fine. It is not our typical opuntia that is native to Ohio as it is more upright. Anyway, please see my photos for my problem. We recently have had cool nights with heavy dew. The white spots have begun to appear on the parts of the plant that are more shaded. They easily wipe off, but is is yellow underneath. The photo of the prickley pear shows this ?fungus? that has appeared. My question is, Is it harmful? What is it? and What can I do about it? Daconil?? Also, if anyone knows what kind of prickley pear it is, that would be great. Thank you. Todd

Here is a link that might be useful: cacti picture