Tis true-the idea being you rinse off the spores and Mildew doesn't germinate in the presence of water. Wet leaves are good. It can also reduce Blackspot(really)by washing the spores off. I do it when Baron Girod L'Ain gets mildew-however you have to do it everyday for a week or so and it will do nothing for the poor contorted leaves that told you that you had Mildew in the first place-of course nothing else does either. You can prevent mildew by washing your roses. Now some people think it actually works because water stressed roses tend to get Mildew and by just watering more....what ever. It does seem to work-at least for me.

patricia

We find it helpful here on the SoCal coast.
The more we wash, the less-likely we are to see mildew or spider mites.
The more the roses are BLASTED with water, the fewer senile leaves hang on to rust.
Of course, in our part of the world, the COST of that water is going up rapidly.

Jeri

This is what I love about Gardenweb-- it's so neat to learn some of this very useful information! I did know that spraying with a hose (or even overhead watering) helps control spider mites. And I make it a regular practice to hit my roses with a good hard blast from the water hose every spring to knock the aphids off (that seems to be enough, around here, to do the trick . . . there's usually just one major onslaught in the spring, and spraying them down hard with the hose controls them pretty well.) But I never knew that water spraying would help with blackspot, rust, and mildew! Cool!

Mites (including spider mites) are like spiders, they hang out where it is dry and warm. They dislike water and moist conditions. So you can usually control them by spraying the foliage with water. But a better, less labor-intensive control is not to use "chemical" fertilizers/plant foods -- none of those aqua powders. Use compost, green sand, etc. to fertilize, or something organic like kelp meal or earthworm castings if you have to give roses a boost.

Mildew is another story -- I've always heard that spraying water will *spread* mildew. BUT, you can very effectively control *powdery* mildew by spraying a milk and water solution -- 9 parts water to one part milk. I have done this and it really works.

This is great - I'm trying this along with Cornell. The Cornell really reduced the appearance of mildew initially, and now I'm trying regular spraying with water. Some improvement along with getting rid of the bad ones has really made a difference - thanks so much Jeri for your advice. Did you see that thread about mildew that was just up on the Roses forum? I wonder if different oils have that much difference in result.

Thanks again for answering my question. I tried the washing method on an HT (Black baccara) and an Angel Face climber in the last few days and it really worked. The new leaves that are sprouting out from the last pruning are mildew free and the older leaves are looking clean with a substantial decrease in the powdery stuff. Both plants are looking really healthy. I noticed the watering also helps a lot with the aphids. I have purchased the ingredients for the Cornell mixture and will try that next.