The fertilizer won't do anything to correct a disease or other health issue, it will only correct low fertility so not helpful unless a nutrient deficiency caused the problem.

Rhododendrons have low nutritional requirements compared to many shrubs and trees - more issues are likely caused by too much fertilizer rather than not enough.

You need to go back to your first question, first post, and try to identify which disease or environmental issue is affecting your shrubs. Treat or correct the condition only after that...

Thanks for the reply. I know what the environmental issue is - when my roof was emergency roof raked in the winter, the rhodie were left in an overly moist environment for too long, which weakened the plant. That won't happen again, unless we continue to get record snow falls.

Regarding the JOBE spikes - the ship has already sailed there. I had some spikes and wanted to get rid of them anyway, so as long as the fertilizer formula for citrus/fruit isn't that far from rhodies, I think I'll be ok.

Okay, so according to your other post, where you link to images, the plant isn't diseased. The problem is environmental stress.

see
http://forums.gardenweb.com/forums/load/azalea/msg0612120929734.html?3http://forums.gardenweb.com/forums/load/azalea/msg0612120929734.html?3

Here is a link that might be useful: not a disesae

Jobe Spikes are a waste of time in my opinion, especially on rhododendrons. As Morz8 says, they don't need much fert, if any, and too much causes problems. You get weak, soft, new growth suseptible to bugs and early frost. Since Rhodies have a fibrous root system, grinding up the spikes and lightly sprinkling them on the mulch above the roots would have been a better way to do it, rather than a concentrated spike.......if you do decide to fertilize them. I know, you already did. Fert will not help any fungus problems and may cause it on new growth.
I have a lot of rhododendrons and have never fertilized them while in the ground and they are very healthy. Of course, I'm in a different climate and don't shovel snow from the roof on them either.
Mike