Hello from an ex New Yorker living in the desert ...

First .. your post is about as misplaced as a post can get ... but no big deal.

"what is this white stuff-fungus? "

Well lets say it's not sugar. Sounds a lot like Fungus but being this is a pro section I won't guess via computer. Let's just say it is Fungus for the time being.

"I tend to over plant crowd "

Fungus like moist conditions .. overcrowding could mean too much shade for some of your plants. This combined with your overhead watering could be making some very moist conditions thats good for Fungus.

I chat rather often with a few New York gardeners and they all tell me this summer in NY has been very long .. hot AND humid .. more so then normal and that is very good for the fungus.

Keep in mind plants are in the photosynthesis business and so make food from light. Too much shade means business could be slow for some of your plants .. that is the plants energy budget may be too low. Unlike goverments when plants run low on energy they can't tax anyone so one department or another gets short changed .. but unlike goverments defense is one of the first areas to be cut. All this means that your plants may be sitting ducks for a Fungus attack.

Also .. plants close together compete for nutrients as well as light ... so this could also make matters worse.

So conditions are looking very good for Fungus.

"I go to the Botanical Gardens in the Bronx, NY and they crowd like crazy and the plants look soooo wonderful."

Another factor in the Fungus equation is that some plants are more prone to attack by certain Fungi then other plants. Where I live place Pittosporum ( Mock Orange ) in a shady spot and you are just asking for Fungus .. that shows up as a white powder all over the leaves. Sounds like your case ???

Here is what you do ... take a sample of the plant's with the white powdery stuff ( that sounds very much like Fungus but may not be Fungus ) to get identified by an extension agent or someone qualified at the Botanical garden or a local nursery.

"How do they get away with that "

No one gets away with anything in the garden world .. what may appear like over crowding to you may not be overcrowding at all .. plants have different growth requirements so one plants ceiling may be another plants floor ... or something like that.

In other words you can mix and match some plants and keep everyone happy .. and some plants are just complete trouble and in certain areas of the country always come down with one disese problem or another.

DON'T run out for a fungicide just yet ... if conditions are really good for Fungus it may not help much at all and some fungicides work on some Fungus and not others.

Anyway I just found out one of my kids has lice .. I'll take your Fungus anyday !!

Don't forget get someone qualified to look at your Fungus thats the key. " Don't forget that .. "

Good Day ...

What you are describing is powdery mildew, a very common fungal disease that is pretty much environmentally related. It is most prevalent late season, as warm, dry soils and high humidity combine to provide a fertile breeding ground for the pathogen. Some plants are particularly susceptible to the problem and tend to contract it regardless of conditions; others will evidence symptoms only when conditions are ripe.

Overcrowding and lack of air circulation can certainly exacerbate the problem - tends to increase humid conditions surrounding the plants. Overhead watering or spraying can also help to spread it. The water splashing distributes the spores and in overcrowded situations, insufficient moisture reaches the root zone. The good news is that except for a few annuals and curcubits, most plants are not seriously affected by PM, other than defoliation or other unsightliness.

Okay - how to prevent/control: first, select plants that tend to be resistant to this problem. Many plants which are prone to PM have been bred to offer mildew resistant cultivars. Allow sufficient spacing between plants so that overcrowding is not an issue. Water early in the day and avoid a lot of overhead sprinkling or spraying - water the root zone, not the foliage. Mulching will help. It will conserve soil moisture, preventing the dry soils that favor the development of PM, and it will prevent a certain amount of the fungal spores splashing back up to reinfect the foliage. Pulling affected annuals and destroying or cutting back other affected plants and removing fallen foliage will help. Various fungicides including the very popular and organic Cornell recipe can be effective in controlling PM, but at best they will be only preventative, not curative. Once you see it on the foliage, it is usually too late for effective treatment, except to keep it from spreading to unaffected foliage.

EDGAR SPRAY THE PLANTS WITH MILK. IVE USED ALL OF THE MAJOR BRANDS AND MOST OF THE HOME REMEDYS FOR THIS . JUST SPRAY WITH MILK EVERY OTHER DAY FOR A WEEK IT SHOULD GO AWAY MILK IS A NATURAL FUNGICIDE