I'm on the opposite side of the bay where summers are warmer. On average right now every day is in the 75-80f with lows around 60f. S.F. famously cool summers tend to be 65f-70f with lows all summer in the mid to upper 50's. Today,80f in Hayward,65f for a HIGH temp in San Francisco. S.F. does Mork have one advantage- winters are a frost free 10b. I get only 10a winters. Some years for me are frost free,but not most..so far. Houston summers are more like the Central Valley in Northern California..near 100 all deep summer until September. Stockton to Sacramento to Red Bluff have blazingly hot summers..but low humidity.

Bayer 3 in 1 contains systemic insecticide and systemic fungicide as well as fertilizer. In Victorville, I seriously doubt you are going to have many, if any, disease issues. I lived in the Santa Clarita Valley for 14 years and never saw any disease issues on Cecile Brunner. The only insects I would expect you to have would be Chili Thrips (eventually, if not already and that because of the heat there) and perhaps aphids in spring and late fall. The Chili Thrips Bayer 3 in 1 probably won't do much for from what I read. Aphids go away when it gets too hot and dry or too cold and wet. So, the suggestions for fertilizers which don't contain the other chemicals are probably much better. My concern would be drainage and how much of these "salts" flush from the soil. My guess is, your home is relatively newer, isn't it? Something built at least since the early 1980's or newer? That matters because of state seismic stability requirements. After the Sylmar earthquake in 1971 then the later ones, including the 1994 Northridge quake, the state enacted soil stability requirements to prevent quake damage. Soft soil slows down the shaking, making it worse and causing greater damage. Harder, more compacted soil allows them to pass quickly, with significantly less shaking and damage. Starting in the early 1980's, builders were required by the state standards to take core samples to insure the soil was uniform, stable and compacted. They must physically dig it out, mix it up and then mechanically compact it to specific density. That squeezes all the air space from the soil, leaving more like bed rock. That means the water can't percolate through it and drainage slows and eventually stops. The roots can't work their way deeply into the soil because there are no air spaces into which they can grow because the soil is squeezed solid, like rock. I dealt with that for many years in the detail gardening business I owned and operated as well as in nurseries I worked and than managed. The soil is so hard, you can't easily dig holes with a shovel and when it gets wet, it's only in the top two to three inches of "top soil" the builder or landscaper spread out over the compacted soil so you could grow sod. What happens is you put the plant in a hole which has slow to no drainage. Eventually that hole fills with water and the plants suffocate and rot. You apply fertilizers which are salts then water them in with water which contains more salts and the desert south west soil already contains salts because it's all ancient sea floor. Those salts build up over time like a soup which boils all day with the water evaporating and the saltiness building by the minute. In soil which drains well, rain and irrigation dissolve those salts and flush them deeper and deeper into the soil, out of the plant root zones. In the compaction scenario, that doesn't happen, so you really have to be aware and not continue putting salts on the ground. If you feel you MUST fertilize, and you are on compacted soil in newer construction, I would only use mild organics which will take longer to digest, break down into their salt forms. It's only the salt form which can move through the root tissues and into the plant. How many times have you fertilized that plant since it was planted? You MIGHT already have more salt in that soil than you want.

The darkening could possibly be honeydew fungus, growing on sucking pest secretions coming from above the affected leaves. Such as from an overhanging tree or shrub, that is infested. If so it will be primarily on the up-facing rose leaf surfaces, where the dripping hits. While this is actively occurring leaves so affected will usually appear glistening and sticky. However maybe you had this happening earlier and now the bugs are gone, but the visual effect produced by the fungus lingers. Again what is needed is close in person examination. Don't undertake any chemical applications or other remedial action until the problem is positively identified.

The rare cane breaks occurred with wind or heavy wet snow. I would have to stake all the tall canes to prevent this rare occurrence and I have too many roses to do this. I have just trimmed the broken spot and new canes have grown. Nothing has died as a result of a cane lost.