We don't have a clue what fungus, if any, you are talking about. What sort of problemo you see onthe leaves?

And if the problem is a fungus which always makes a mess of that rose, perhaps it's time to discard the plant, then obtain a more toleraant one.

Are you speaking of black spot or powdery mildew? How are you watering these bushes? To begin, you can spray roses with a tablespoon of baking soda disolved in a gallon of water in a pump up sprayer. You can also make a slurry of corn meal and water and apply this to the folage. Not sure why you are fertilizing roses with a fertilizer for hollies. This line of fertilizer also has a rosetone product. I use an organic fertilizer which has alfalfa as the main product. You don't want to fertilize this late as it will cause new growth which may be killed by frost. In the spring remove all mulch from the beds and allow the sun to clean the soil. Add a liberal sprinkle of corn meal which will kill fungle spoors in the soil. Also add a third cup of a good organic fertilizer to each bush and lightly scratch it into the soil so not to damage the roots. Then add new mulch to your beds 2-4" thick. If you have it, pine straw makes excellent free mulch for roses and provides a little acid which roses like especially if you have alkaline soil. Hope this is helpful.