Hello. I have a very large, old, and sentimental jade plant. Over this winter it has developed a powdery mildew infestation. I have searched articles and read a lot about how to treat, and everything I read is saying to remove the infected leaves/stems, and then spray to prevent further spread. The problem is, if I remove all the infected leaves, it will greatly reduce the size and shape of the plant. Has anyone successfully conquered an infection like this by just spraying with Neem oil or another fungicide? Do you think I have to remove all the infected leaves/stems? I hate to destroy it. Its in a sunroom, gets lots of light, plenty of air, so I am not sure how it even got mildew, but if anyone has advice on that I'll take that too. Thanks!

Tebuconazole is a systemic fungicide that acts both as a prophylactic and curative. It's very effective on powdery mildew. You can find it over the counter in several forms. I use it as a topical spray (Bayer 3-in-1 for insects disease and mites). The product also contains a systemic insecticide (imidacloprid) and a miticide (tau-valfluvinate [sp?]). Read instructions carefully, spray outdoors, and wait until the spray has dried to bring the plant indoors. Do not use more than the instructions direct.

Al

I'm seeing pm as the first probable cause, followed by salt/mineral deposits.

Not familiar enough w/pm on jades in particular, so not disagreeing.

But what kind of water do you have?

We are on well water, its neither hard nor soft. I really don't think its the water. I have another jade, a child of this one, that is also covered. These pics may be easier to see. Its like a layer of fuzzy white stuff. I think this one is a total loss.

I'm going to try and spray it. I am in the northeast, so I can't bring it outside to spray just yet, its much too cold. So will try something i can spray inside and see what happens.

I would remove all older damaged leaves and also trim the tips a lot! It really needs to get denser. Then spray what's left. It'll regrow, don't worry and look better than ever. Once it is above 40F at night you can put it outside.
I would also remove lower horizontal branches to the main trunk: so you have more of a tree look.