Roses should never be sprayed when their roots are dry. i.e., water well the previous day.

And in real heat, you risk spray burn.

Jeri

South Florida doesn't really have extreme heat. If you are using modern chemicals such as Bayer, Banner, or Rose Pride, it should be OK to continue spraying through the summer. Morning is safest, and be sure the plants are well hydrated.

When I first began spraying I was told not to spray when the temperature was over 85. That has been many, many years ago and whether it had to do with the product I was using (Fungunex) or its components (surfactant) I can't remember. All I know is that if I spray when it's over 85 (with well hydrated roses being a given) I usually end up with some spray damage. Now we have very humid heat so that may play a factor. Again, this is my personal experience and while I've heard that others in the south ignore the over 85 advice, I still adhere to it. These are your roses however so you are free to do what you wish.

You should water deeply before spraying anything. BUT, once that spray program has started, you MUST continue it. Water deeply and spray.

Funny, I was just reading a recommendation in the Houston Rose Society newsletter that you CONTINUE TO SPRAY on a regular schedule. Folks, it has been over 100 every day for the past 6 weeks or so and DRY. On the weather at 10:00 at night, many times is still in the mid 90's! They do say to spray in the early morning or late evening but it is still very warm then.

This went against everything I thought about spraying (i.e. DON'T spray when it is really hot). I haven't been spraying anything anyway but I was very surprised by this recommendation.

Lynn

My experience is that when really HOT weather arrives, I do not need to spray. I'm talking about regular temps in the 95-100+ range--which often is most of our July and August here in Zone 6 Kansas. BS doesn't seem to develop in those temps--too hot for me and for the BS, I guess. Anyway, I don't spray during that time period.

But, of course, I'm kinda lazy and probably like finding excuses not to spray. As long as not spraying works, that's fine with me. : )

Kate

People are still repeating slogans from 30-50 years ago when a majority of common rose sprays were fairly phytotoxic. It depends on what you spray. I haven't seen any evidence that Banner or Bayer cause problems if sprayed correctly.

On the other hand, you probably don't need to spray when temperature lows are 80 or highs are 100, because it's just too hot for fungi to flourish.

I find spraying my least favorite thing to do with roses. When summer heats up Powdery Mildew is not a problem so I don't have to spray for that. When it comes to Blackspot in summer it's not the day time highs you need to look at, but the night time lows. It can get awful dewy over night if the temperatures fall enough. For me if nighttime temps are around 80 or upwards I skip spraying in the summer heat and drought (with one eye on the weather forecast). However one year we had a surprise thunderstorm and the BS hit with a vengence making some of my non BS resistant roses look like I was a rank amateur. That taught me a valuable lesson. Get rid of varieties that need to be sprayed religiously. I don't want to go to the church of "must always spray".