Weather forecasts drive me nuts.

Basically, I avoid spraying in full sun like I'm avoiding the plague, reason number one is that I do not want the invaluable spray to dry on the foliage too fast before it can be fully absorbed. Therefore, on a predicted full sunny day, I schedule spraying late in the day, or preferably, early in the morning before sunlight hits the foliage, but yet enough light is provided by the sun so that I can see adequately to not trip all over myself.

Secondly, I do not want a photo reaction to occur by the spray negatively effecting the foliage from the full sun beating down on it. Therefore I avoid spraying in full sunlight for this reason, too.

Then there's daytime temperatures. If the temperature is above 75-80°F, except on overcast conditions, I wait until the temps are below that marker to spray.

My goal is for the spray applied to do the best job it can do. So allowing it to be absorbed/dry as slowly as possible, and not cause foliage damage, or dry too fast because of full sun/hot temperatures is always in my mind set come time to spray.

Everything I spray: systemic insecticide to control the dreaded Rose Midge Fly, fungicide for black spot (still have to spray a little in spite of trying to maintain a policy of black spot resistant roses only in my garden), and miticide for the two spotted devil, is supposed to be for the most part, at its peak effectiveness at the prescribed application rate ONCE THE FOLIAGE HAS COMPLETELY DRIED AFTER SPRAYING.

Moses.

bart bart when I sprayed my garden regularly, I just picked whatever time of the day seemed further from the rain and sprayed. I felt like as long as the spray got time to dry on the plants it was fine and not really stressed on counting 24 hours or anything like that.

We stopped spraying when I realized that my husband, who dragged the spray cart around, was not wearing goggles and a paint-spray level respirator. We didn't really discuss it, I just stopped mixing the chemicals.

OK, now that I can think to type some more caveats. Some roses may have such a bad case of Black Spot that they not only can't be cured, but they will infect and affect any roses downwind of them.

I bought over a hundred roses for a dollar each frm Park Wayside one summer. I got to see a lot of things. One was a rose with "Perfume" in the title and I really wanted it do do well. All it did well was get massive black spot and drop leaves continuously I thought to treat it with twice weekly fungicide. Its black spot ignored my efforts. Finally after four months it was dug up and taken to our burn pile and its adjacent roses recovered.

The drying time often varies with what you are spraying. I don't know what the EU is allowing this year. One thing that makes a difference is using a spreader-sticker in the spray. Sometimes it is used to adjust the pH of the spray (one of the much loved in North America fungicides works much better with a partiicular pH)

An Herbicide we use on the Grass from H.... aka Johnson Grass, dries in two hours and that's with a particular spreader that comes with the herbicide from one manufacturer, but not with a more dilute version sold for home gardens. We had bought the home version and it was worthless and our problem became so invasive I talked to people until I found out what did work.

Thank you all for your comments and help. I've been spraying only organic things that are supposed to stimulate the plants' natural defenses-lecithin,this Rocksil thing which is some kind of powder from rocks (?), etc. I'd like to do maybe one systemic fungicide of the nasty sort, but am kind of scared, even though I do have and intend to use my respirator mask, goggles and gloves. This is only on the new implants; the established roses don't need it. I'm not trying to fight bspot or PM; my goal is to keep the plants as strong as possible and clean as possible in the hopes that they will not succumb to the "creeping black finger of death" sindrome that has been tormenting my new implants these past few seasons. The plants look fine until the beginning of August, when suddenly these black lesions appear near the base of some of the canes,and said canes then die. The roses in question are all supposed to be pretty disease-resistant,yet still this happens. At this point I think it's probably bacterial,since I have been shading them and watering as best as I can. Of course, fungicides won't help with bacterial issues per se; the goal is merely to keep the new young plants as healthy as I can in the hopes that they will resist this die-back.