I’m far from an expert on diseases. That said photo number two looks like downey mildew. I would think your temps may have been too hot for downey. It’s just that the dark spots are not crossing the leaf veins. Look up Downey mildew and see what you think.

I second the downey mildew if the rose plant is not in full sun. The top one looks like it wants some magnesium. If it isn't that ,then there is something in the soil that is annoying the rose.

I appreciate the replies and thank you for them.

There's only one plant with the problem shown in the first photo. I can certainly add some magnesium and see how it results.

There's quite a few plants with the problems shown in the 2nd picture. All the problem plants are in full sun (8+ hrs/day). The ones in partial shade in either morning or afternoon times do not have this problem.

By the way, what could be the annoying element in the soil if it's not magnesium deficiency?

How much soil is in the pot. Is the soil kept to moist by any chance. Poor root development could interfere in nutrient uptake.

The pot and soil are new as of February this year.

It does collect water during rainfall but otherwise it's slightly moist. There's a total of 6 potted roses, none of the others exhibit the same disease characteristic. This plant in particular had been very healthy until sometime in the past 2 weeks (work travels). Let me find a picture of the plant in it's healthy days.

Same plant in the 1st pic, a month ago.

Top photo looks like mosaic.

Ughh. I was afraid it could be Rose Mosiac too but I'll try the Epsom salt approach. If it's the mosiac virus, it is truly a sad thing to witness. This plant has been on a tear with blooms.

Has anyone used Physan 20 to clear up Downey Mildew?

Dvs FL

I have rose mosiac in several roses on Fortuniana.Usually It goes away in hot summer months .l read in another thread that someone used Organicide successfully in FL for Downy Mildew.

Being the Rose newbie that I am, I pruned the plant back. Oops my bad. I'll add some Epsom salt in the morning.

Treated the infected roses this morning. Added Epsom salts to the other plant. Let's see how it goes.

In case you are not familiar with Daconil"s active ingredient:

https://en.wikipedia.org/wiki/Chlorothalonil

Hello Henry. I'm assuming your comment is to alert to the toxicity of the product. I totally understand pesticides, fungicides and insecticides can be harmful but they serve a purpose.

Is there a safer compound to use with the same or better efficacy? I'm always open to using a substitute product with same or better results.

The question was: "Is there a safer compound to use with the same or better efficacy? "

I cannot try to answer the "same or better efficacy part without understanding why you are you using Daconil.

Concerning the safer compound part:

It appears that New Jersey is not thrilled with it.

http://nj.gov/health/eoh/rtkweb/documents/fs/0415.pdf

I've been told by an experienced Gardener it's an effective compound to kill certain maladies like rust and Downy Mildew.

So back to my question... What compound is just as effective if not better than Daconil? I'm interested in using a better compound to kill the issue at hand while being less or not harmful to humans.

I wonder what others have to say about using Daconil for Downy mildew.

"Fungicides commonly used for black spot control such as Daconil (chlorothalonil), Funginex (triforene), Bayer systemic fungicide (tebuconazole), Fertilome systemic fungicide (propriconazole, includes Banner Maxx), Immuninex (myclobutanil, also includes Eagle) and Clearys 3336 (thiophanate methyl) will be ineffective for control of downy mildew."

https://www.amerinursery.com/growing/media/downy-mildew-of-rose/

Rose rust in the heat of Florida?

For rose problems in Florida, I recommend Florida solutions.

" Rose rust is rarely seen in Florida and then it usually appears on plants shipped in from out of state. Dithane M-45 and Funginex are recommended for control if it should occur, along with careful sanitation. The same applies to Downy Mildew which has been known to appear at infrequent intervals."

http://gardeningsolutions.ifas.ufl.edu/mastergardener/newsletter/2008/rose_faq.shtml

Organic rose forum discussions of rust:

https://www.houzz.com/discussions/organic-rose-growing/query/rust/nqrw

I have not had a chance to go through this thoroughly.

http://ir4.rutgers.edu/Ornamental/SummaryReports/DownyMildewDataSummary2017.pdf

I'm a newbie to growing roses, and have a lot yet to learn. I took the advice from the Gardener as good. You provided great alternatives I need to review. Thank you for this information.

It's interesting most of the roses with rust and downy mildew problems were shipped in from other states, but a few were from in state.

As for Rose issues in Florida, I must be a magnet in attracting them. I had 3 Rose plants die mysteriously in April, less than 2 weeks after buying them as healthy plants with lush, abundant foliage. No bug infection detected, watered properly on occasion, great all day sun position. So issues are no longer a surprise for me when they appear.

This is just a suggestion. If you used a reasonable potting soil, I would be very careful adding anything to the soil other than a proper fertilizer. Actually I would not do it at all.