Yes, the conditions resulting in "June Gloom" cause many of the PM issues. But, they also reduce the oppressive heat making it nicer for the rest of us to live. Yes, many of us deliberately avoid "mildew magnates". Yes, once it warms and dries up, many of the PM issues will go away, as long as they aren't due to 1. genetic mildew magnates; 2. other specific micro climate or cultural issues promoting the PM. I don't know what they use at The Tournament House for the issue, nor do I have any idea why they have few mauves and purples. Back when Bartje Miller was in charge, I could have easily been able to find out the answers to your questions. Kim

As my roses got really established, the PM pretty much vanished and never came back. June Gloom season sadly is about over. A warm up next week, the heat will be on. Gardening season is over and the watering season begins.

I thought of you yesterday Henry, at the Huntington. The rose garden looks fabulous again, if you get over there in the next few days before the heat really hits, maybe you'll be more pleased with it.

This post was edited by hoovb on Thu, Jun 20, 13 at 20:35

Over the years, we found there were some roses which were simply going to mildew in our coastal climate. (Here, the "June Gloom" is far more pervasive than it is further inland.)

So you divide between roses that outgrow PM as the plant matures, and roses that just mildew, no matter what.

We made a decision years ago not to spray -- after seeing the sprays cause our dog to seizure.

So, roses which stubbornly mildew are removed from our garden. (We will tolerate temporary small outbreaks.) That seems to us to be a sensible decision on all levels. Thus, we have a garden where disease is fairly rare, and which makes us happy.

Jeri

Between an overhanging tree and June gloom, I do have some mildew, Yves Piaget and Sharifa Asma being the worst, but the tree has been trimmed back and June gloom is on its way out, so things will get better in time. I've never sprayed for mildew.

The worst of all, though, is Tropicana. I tried to SP it, but it just came back, mildew and all.

Maybe the Tournament House sprays, or they could be in a little micro-zone which has good air circulation and less mildew-producing conditions.

Between an overhanging tree and June gloom, I do have some mildew, Yves Piaget and Sharifa Asma being the worst, but the tree has been trimmed back and June gloom is on its way out, so things will get better in time. I've never sprayed for mildew.

The worst of all, though, is Tropicana. I tried to SP it, but it just came back, mildew and all.

Maybe the Tournament House sprays, or they could be in a little micro-zone which has good air circulation and less mildew-producing conditions.

Coming from Connecticut I'm almost totally inexperienced with PM. The worst rose here with it is McCartney which never had PM problems back in CT. And I should say that half of the roses here don't even have a PM problem which means that something else must be going on. Where there is a problem it is mainly the new growth which seems like it can be killed or stunted by PM so I don't just want to ignore it. And BTW there is mildew on other things besides roses and it is not consistent. I seem to have smaller micro-climates within our main micro-climate.

Henry, you will find many micro climates in your garden. They are EASY to accidentally create. Roseblushlyn grew Sweet Chariot in her front garden here in SoCal where it mildewed badly. She moved it around to her back garden and it never mildewed again. Sometimes all it takes is cutting something near the plant back to provide less humidity and more air flow, or even more direct sun. Quite often, mildew problems arise because the rose isn't receiving sufficient water. I'd read in LeGrice and Harkness that water stress could cause mildew even when conditions didn't support the fungus. I never believed it until I DID it in nearly triple digit heat with near single digit humidity. You can also force many roses to rust badly due to insufficient water.

Penelope at a client's house mildews badly because of the reflected, radiated heat from the block wall it grows on. No matter how much water it's given, when the temps climb, the heat bakes out more water than the plant can absorb, so I have to use systemic fungicide on it to keep it clean.

t home, I will move a rose (and other plants) around to determine where they are going to be most satisfied, before planting them. You'll be surprised how many not only don't need, but actually suffer from as much sun as you're used to providing. Others stretch out in the heat like an old cat. The one constant though is, in this extreme heat, aridity, sun intensity, as long as your drainage is sufficient, you can NOT over water! You might also try overhead watering with an oscillating sprinkler. You will be amazed how huge,clean and bug free your foliage is when it really gets cooking here! Kim

Here in Livermore (hot and dry summers with occasional marine influence usually -- but a lot of marine influence for some strange reason this year), I cured the persistent powdery mildew on shrub-form Devoniensis by moving the plant from the east side of my back yard to the west side of my back yard. Like magic, no PM thereafter.

I have also (inadvertently) done the experiment with too little water and instigated PM. The same plants, if well-watered, do not get PM nearly as bad as when they are not watered well.

And, as said before, some roses get terrible PM no matter what you do. They are soon gone from this garden (so, the answer to your question about avoiding is "yes" in my case -- too many great roses that don't get PM to suffer with the blight and effort required with one that does. Every day I see my neighbor's 'Dorothy Perkins' peering over the fence as a reminder of what a dedicated mildew-er can achieve, blight-wise.)

This post was edited by catspa on Fri, Jun 21, 13 at 19:10

I've become ruthless about roses that insist on mildewing. If I can't prevent the problem by changing the location, I can live without that rose. Period.

Jeri