You could probably spray Bayer, Immunox, or Banner, if mixed correctly, in full sun at 10 A.M. If the label doesn't contain a caution, I wouldn't be anxious. I feel we have some folklore on this issue that is passed down from the time that growers sprayed a mixture of several phytotoxic chemicals such as Phaltan, Plictran, and Sevin. Nowadays, once in a while somebody forgets to swirl the tank or sprays drought-stricken plants, and that provides an anecdote about the dangers of spraying in daylight.

I use relatively phytotoxic materials such as sulfur, soap, and occasionally Daconil. I'm not afraid of sunlight as long as the plants are not stressed by heat and drought (which mine never are).

Hi Deb,
I don't particularly worry about sun because I always spray relatively early in the morning or very late in the afternoon.

What I pay special attention to is how much wind there is. I try to pick the most windless day I can. Interestingly, earlier morning and later afternoon is when there is often a period of time when the wind disappears--a period of calm. That's probably why I got into the habit of spraying at those times. Let's face it--I really don't want to be breathing in any spray the wind wants to direct back at ME!

Kate

I try to do it early in the am. So even if it is sunny, it wont be enough to burn the leaves.

I agree with Michael's and Kate's comments regarding spraying & sunlight. As Michael indicated, it's always a very good idea to water your roses well a day or two before you spray.

I consider late afternoon to be the ideal time to spray. I generally have lots of dew on my plants early in the morning, especially during the hottest months. I think the spray is more effective when it's applied to dry foliage -- plus there's the problem of not being able to tell where you've sprayed & where you haven't when the foliage is already moist.

Like Kate, I pay attention to predictions of wind conditions. I just don't spray on really breezy days.

I spray usually before 10 AM as michaelg notes. My garden is south facing and in full sun from early in the morning. I have no choice. I also try to water the evening before when I get home, but if I don't, then the drip irrigation is on while I'm spraying.

We had a talk at the last RS meeting, and a CR from Philly says that he's moved to spraying in late afternoon/early evening too. Allows for sleeping in..., ur, getting those weekend errands done.

It rained here over 3 inches in the last 5 days. Otherwise, I typically do water right before spraying or the day before.

But, are you saying it is okay, assuming proper hydration, to spray at 10 AM in full sun? Of course early evening there is no sun/little sun left and that is when I usually spray out of necessity. But I don't like spraying then!

What do you consider early morning? With small kids we are usually up by 7ish on the weekend, sometimes before, ugh, but I have not considered doing it then just because I thought it was too sunny.

Years back, Cindi's friend George in SE Texas said he sprayed Banner + mancozeb at midday in hot summer weather every two weeks with no problems. One of my points is that many modern chemicals are not phytotoxic except under conditions of extreme negligence. Read the label and see if there is a caution about temperature. If not, there's nothing to worry about if you have watered, measured carefully, and agitated the tank.

Michael, you always taught me to add water to the tank and then the chemical so I do. (See, I do remember what you say =-). What is the reason for that, just curious?

Redsox, some materials will stick to the bottom of the tank and resist mixing. Then a glaze builds up in the tank. Thanks for remembering ;)

What exactly are you spraying? I spray with the Bayer Advanced stuff and I spray rather randomly so I have sprayed even at noon on hot days and it's been fine. I try to avoid spraying when it is too hot and sunny, but that's more for my health than for the roses.

I'm spraying the Bayer Advanced Disease Control also.

I was a spray person for long time. It can be quite hot here in summer. 90-95 can be for weeks and 100 for days. When I sprayed sulfur, I learned that it will burn at temp higher then 80, no matter what, sun or shade. When I sprayed Banner Maxx I NEVER payed any attention on what is temperature, how sunny it is or what time of the day I spray. I did spray at noon, at 2-3 pm, etc. Never got even the slightest burn. I always have my plants watered well day before spraying.
Olga

Fill the tank halfway, add the spay and finish filling the tank. I don't like to spray when there are honey bees and ladybugs about so I spray in the evening or even after dark. (The garden has floodlights.) Also it is usually calm at night. And BTW, another reason not to use pesticide is that there are many harmless bugs that you might kill that you don't even know about. There are many kinds of moths including some really big ones, lightning bugs and june bugs which sit on the leaves but don't do any harm. You also occasionally see bumble bees sleeping in the blooms. I always think sleep little bumble bee. I wont hurt you.

Not mentioned specifically above, but hidden in the comment from MichaelG about Cindi's friend George:
I do know George and he gardens in southeastern most Texas. Mid day works for him. What y'all may not know about that part of the Gulf Coast is that in the morning, summer (all eight months of it), the humidity when you wake up is often 100%. It stays 100% until 9 or 10 in the morning. Were he to spray then, the spray on the leaves wouldn't dry and when the sun hit it, it would be more likely to burn where there were droplets. But by waiting till noon, the humidity drops, the temperature rises, and the spray dries fast on the leaves. And that's what you want.

Leaving the leaves wet in some some temperature ranges is a way to encourage Black Spot.