Not sure what you mean by webby stuff, unless it's actual spider webs, in which case, it's not a problem. Spiders eat bugs, so they're your buddy :)
Is the fungus on the rose of sharon on the leaves or on the wood? If it's on the wood, you could possibly prune out and destroy the affected wood, then see what happens from there.
I have a lot of ants in the garden, but they've never caused me a problem. However, some folks have fire ants, and massive infestations of ants that they have to deal with, I'll let one of them address your ant situation.
The first step to dealing with any pest or problem in the garden is to identify it. Once you've identified it, you can find out what your options are. It's not usually a good idea to treat anything until you know exactly what it is, and if it's a pest/problem or not.
For what it's worth, I don't use anything stronger than an occasional dose of round-up on a particularly hard to kill weed. For the rest, Mother Nature seems to be keeping things in balance. I see a chewed leaf here and there, but nothing major.

Is it powdery mildew?

You can spray it with a solution of epsom salts (I forget the ratio, but I'd bet someone on the Organic Gardening Forum would know.)

I've also heard that milk is effective as a spray.

I've got powdery mildew this year, never had it before in the 12 years I've been gardening at this place.

I suspect lots of us have things "never seen before" due to last year's weird, wet, cool weather.

Best luck!

sylvia

it's hard to tell exact problem you have. most obvious assumption of webbing might be spider, or spidermite, if it's spider it's friend, if it's spidermite, it's your enemy. with out picture's it'll be hard to tell. ants are the same way. most ants doesn't creat any problem in your garden, some spieces do. again,hard to tell which is which. also there are tone of different fungal disease. some are quite natural for a plant to get it and they do very minimal damage that you don't really have to worry about. some can kill a plant right a way, definatly more serious epidemic. long and short of it is that it is hard to know which is which and what or what not to worry about. the best is in prevention- if you have fungal problem, exam bed, is it too crowded? you need good air circulation so the moist don't get traped in between. watering should be done early part of the day. replacement of the fungacides.... it'll depends on what fugal disease you have. one solution doesn't work for everything. but it starts from getting rid of infected leave. or branch . make sure you don't leave any infected part on the ground, and disinfect the tool in between cuts. if they withstand losing some leaves and branches , then this fungal disease is nothing to worry about. it's ok to have some pest and disease in the garden as long as it's not out of control.