There is Rust colored motling of Rose leaves as you can see in the picture. what could be the reason. thanks.
Could you try again with a sharply focused picture?
Please try removing several of the leaves, placing them on a flat surface and taking as close-up photos in as sharp focus as possible. What you're showing could be insect damage due to the sap being sucked out of them; the beginning of a disease or nutrient deficiency, but the ONLY way to even begin to diagnose which it may be is to see clear, detailed photos of both tops and bottoms of several leaves. Plus, if you get sharp, close-ups of the reverses, it should be possible to tell if there are spider mites, which could easily result in the mottling of the foliage you are questioning. Kim
If you have a flatbed scanner, you can get clearer, better images using that, than you can with a "point and shoot" camera, or most cell phones.
If you don't have a better camera, and you don't have a flatbed scanner, try a business that has one, and/or does printing, and use their scanner.
Or sunburn. Have you had a sudden heat wave? But yeah, a photo that's in focus would really help us to help you.
Rust colored mottling of Rose leaves, close up
Rust colored motling of Rose leaves, undersurface of the leaves.
I think these roses are infested with spider mites, which would cause the fine yellowish stippling on top and the dirty appearance of the undersides. Look at the undersides through a magnifier, preferably 6x, and I think you will see wispy webs, tiny amber colored crablike critters, and perhaps their yellowish eggs. They suck plant juices and will eventually cause the leaves to curl and die.
The Two-Spotted Mite is everywhere, but population explosions can occur a) when roses are grown indoors or sheltered from rain b) when insecticides have reduced their natural enemies c) in hot dry weather. Outbreaks are best treated with water--a hard spray directed to the undersides every day or two. Have you used an insecticide?
I am not sure what caused the brown mottling. but it is probably not a fungus disease. The dead brown patches that I think I see in the first fuzzy picture seem different and could be burn from too much fertilizer.
I am guilty of, or a victim of , everything mentioned.