Is this heat related? Deficiency?
How old is this rose? What have you been using as a fertilizer (type and amount/frequency)? Have you sprayed it with anything? It looks like spray burn to me.
Marginal browning is usually fertilizer burn / salt poisoning involving some combination of too much fertilizer, too little water, and heat. I can't see fine detail in the image, but fertilizer burn often presents as disc-shaped spots that run together. You can also get oozy-shaped areas that start off looking water-soaked and then dry crispy brown.
What should I do? Flush it with water?
Yes, more than five gallons, and see that it gets an inch of water per week through the summer. Reduce fertilizer when it is extremely hot. Come back in a few weeks and let us know.
Thx.will do.i spread some bone meal on top layer ,and I think that did the damage.
Actually bone meal is inert and has little effect on the soil or plant.